CNIM Board Prep

1. The homunculus is a

Representation of the motor and sensory cortex of the brain

Gyrus found in the temporal lobe

Lateral loss of vision in one eye

Type of tumor

The homunculus is a representation of the motor and sensory cortex of the brain. It is a visual depiction of how different parts of the body are represented in the brain. In the motor cortex, the homunculus shows the areas that control movement for different body parts, with larger areas representing parts of the body that require more precise control. In the sensory cortex, the homunculus shows the areas that receive sensory input from different body parts, with larger areas representing parts of the body that are more sensitive or have more sensory receptors. This representation helps to understand the organization and function of the brain.

Explanation

The homunculus is a representation of the motor and sensory cortex of the brain. It is a visual depiction of how different parts of the body are represented in the brain. In the motor cortex, the homunculus shows the areas that control movement for different body parts, with larger areas representing parts of the body that require more precise control. In the sensory cortex, the homunculus shows the areas that receive sensory input from different body parts, with larger areas representing parts of the body that are more sensitive or have more sensory receptors. This representation helps to understand the organization and function of the brain.

2. Which of the following is an effect of temperature on somatosensory evoked potentials?

Cooler temperatures tend to accelerate central conduction time

Warmer temperatures tend to polarize the stimulus current

Cooler temperatures tend to slow peripheral conduction time

Warmer temperatures desensitize nerve endings

Cooler temperatures tend to slow peripheral conduction time because cold temperatures can decrease nerve conduction velocity. This is due to the fact that cold temperatures can cause vasoconstriction, which reduces blood flow to the nerves and slows down the conduction of electrical signals along the nerves. As a result, the somatosensory evoked potentials, which are electrical signals generated by sensory nerves in response to stimulation, will take longer to travel from the peripheral nerves to the central nervous system.

Explanation

Cooler temperatures tend to slow peripheral conduction time because cold temperatures can decrease nerve conduction velocity. This is due to the fact that cold temperatures can cause vasoconstriction, which reduces blood flow to the nerves and slows down the conduction of electrical signals along the nerves. As a result, the somatosensory evoked potentials, which are electrical signals generated by sensory nerves in response to stimulation, will take longer to travel from the peripheral nerves to the central nervous system.

3. What nerve controls motor function for plantar flexion of the toes and sensory distribution for the plantar aspect of the foot?

Median

Ulnar

Posterior tibial

CN VIII

The posterior tibial nerve controls motor function for plantar flexion of the toes and sensory distribution for the plantar aspect of the foot.

Explanation

The posterior tibial nerve controls motor function for plantar flexion of the toes and sensory distribution for the plantar aspect of the foot.

4. Near Field

Corrected visual acuity

Stimulus field close to the eyes

Area within three feet of eyes

Generators close to the recording electrodes

The correct answer is "Generators close to the recording electrodes". This suggests that the generators, which are likely electrical devices or sources of signals, are located in close proximity to the recording electrodes. This proximity is important for accurate recording of the signals generated by these devices.

Explanation

The correct answer is "Generators close to the recording electrodes". This suggests that the generators, which are likely electrical devices or sources of signals, are located in close proximity to the recording electrodes. This proximity is important for accurate recording of the signals generated by these devices.

5. Routine intraoperative electrophysiological monitoring documentation should include

Heart rate

Blood pressure

Respiratory rate

Blood plasma volume

Routine intraoperative electrophysiological monitoring is essential to assess the patient's physiological status during surgery. It helps in detecting any changes or abnormalities that may occur during the procedure. Blood pressure is a crucial parameter to monitor as it reflects the force exerted by the blood against the walls of the blood vessels. Fluctuations in blood pressure can indicate potential complications such as hypotension or hypertension. By including blood pressure in the documentation, healthcare professionals can track the patient's cardiovascular stability and make necessary interventions if required.

Explanation

Routine intraoperative electrophysiological monitoring is essential to assess the patient's physiological status during surgery. It helps in detecting any changes or abnormalities that may occur during the procedure. Blood pressure is a crucial parameter to monitor as it reflects the force exerted by the blood against the walls of the blood vessels. Fluctuations in blood pressure can indicate potential complications such as hypotension or hypertension. By including blood pressure in the documentation, healthcare professionals can track the patient's cardiovascular stability and make necessary interventions if required.

6. What is the difference between constant voltage and constant current?

There is not difference between constant voltage and constant current.

None of these

Constant voltage and constant current are two different methods of supplying electrical power. In constant voltage, the voltage remains constant while the current can vary based on fluctuations in impedance or resistance. This means that as impedance or resistance changes, the current will increase or decrease accordingly. On the other hand, in constant current, the current remains constant while the voltage can vary to accommodate for fluctuations in impedance or resistance. This means that as impedance or resistance changes, the voltage will increase or decrease to maintain a constant current flow.

Explanation

Constant voltage and constant current are two different methods of supplying electrical power. In constant voltage, the voltage remains constant while the current can vary based on fluctuations in impedance or resistance. This means that as impedance or resistance changes, the current will increase or decrease accordingly. On the other hand, in constant current, the current remains constant while the voltage can vary to accommodate for fluctuations in impedance or resistance. This means that as impedance or resistance changes, the voltage will increase or decrease to maintain a constant current flow.

7. The type of electrode most commonly used in an intensive care unit or operating room setting is ___.

Percutaneous electrode

Epidural electrode

Subdermal electrode

Kirsher electrode

The subdermal electrode is the most commonly used type of electrode in an intensive care unit or operating room setting. This electrode is inserted beneath the skin, directly into the muscle or nerve tissue, to measure electrical activity. It provides accurate and reliable readings, making it ideal for critical care environments where precise monitoring is necessary. Percutaneous electrodes are inserted through the skin, but they are not as commonly used in these settings. Epidural electrodes are used for pain management, and Kirsher electrodes are not commonly used in medical settings.

Explanation

The subdermal electrode is the most commonly used type of electrode in an intensive care unit or operating room setting. This electrode is inserted beneath the skin, directly into the muscle or nerve tissue, to measure electrical activity. It provides accurate and reliable readings, making it ideal for critical care environments where precise monitoring is necessary. Percutaneous electrodes are inserted through the skin, but they are not as commonly used in these settings. Epidural electrodes are used for pain management, and Kirsher electrodes are not commonly used in medical settings.

8. The type of electrode most commonly used in an intensive care unit or operating room setting is ___.

Percutaneous electrode

Epidural electrode

Subdermal electrode

Kirsher electrode

The most commonly used type of electrode in an intensive care unit or operating room setting is a subdermal electrode. This type of electrode is placed beneath the skin and is used to monitor electrical activity in the body. It is often used for procedures that require continuous monitoring, such as surgeries or critical care situations. The subdermal electrode is preferred in these settings because it provides accurate and reliable readings, allowing healthcare professionals to closely monitor the patient's condition.

Explanation

The most commonly used type of electrode in an intensive care unit or operating room setting is a subdermal electrode. This type of electrode is placed beneath the skin and is used to monitor electrical activity in the body. It is often used for procedures that require continuous monitoring, such as surgeries or critical care situations. The subdermal electrode is preferred in these settings because it provides accurate and reliable readings, allowing healthcare professionals to closely monitor the patient's condition.

9. It is important to put a note in the patient chart:

So that a professional fee can be billed

In case the circulator doesn’t remember you

To prove that you looked through the patient chart

As an attestation that you were present doing the monitoring

Putting a note in the patient chart serves as an attestation that the individual was present and actively monitoring the patient. This is important for documentation and accountability purposes, as it provides evidence of the healthcare professional's involvement in the patient's care.

Explanation

Putting a note in the patient chart serves as an attestation that the individual was present and actively monitoring the patient. This is important for documentation and accountability purposes, as it provides evidence of the healthcare professional's involvement in the patient's care.

10. What spinal tract is being stimulated when running transcranial motor evoked potentials?

Rubrospinal

Tectospinal

Dorsal columns

Corticospinal

When running transcranial motor evoked potentials, the spinal tract being stimulated is the corticospinal tract. This tract is responsible for transmitting motor signals from the brain to the spinal cord and ultimately to the muscles. Stimulation of the corticospinal tract can help assess the integrity and function of the motor pathway. The other options, such as the rubrospinal, tectospinal, and dorsal columns, are not directly involved in transmitting motor signals from the brain to the spinal cord.

Explanation

When running transcranial motor evoked potentials, the spinal tract being stimulated is the corticospinal tract. This tract is responsible for transmitting motor signals from the brain to the spinal cord and ultimately to the muscles. Stimulation of the corticospinal tract can help assess the integrity and function of the motor pathway. The other options, such as the rubrospinal, tectospinal, and dorsal columns, are not directly involved in transmitting motor signals from the brain to the spinal cord.

11. Transcranial motor evoked potentials are best elicited when using

Complete neuromuscular blockade

A train of stimuli

Halogenated agents

Stimulus rates above 20/ sec

Transcranial motor evoked potentials are best elicited when using a train of stimuli. This means that multiple electrical stimuli are delivered in rapid succession to the motor cortex, resulting in a stronger and more reliable response. Using a train of stimuli helps to overcome the variability and potential noise in the signal, improving the accuracy and consistency of the motor evoked potentials.

Explanation

Transcranial motor evoked potentials are best elicited when using a train of stimuli. This means that multiple electrical stimuli are delivered in rapid succession to the motor cortex, resulting in a stronger and more reliable response. Using a train of stimuli helps to overcome the variability and potential noise in the signal, improving the accuracy and consistency of the motor evoked potentials.

12. The layers of protective tissue surrounding the CNS:

The ventricles

The meninges

The CSF

The skull

The meninges are the layers of protective tissue surrounding the central nervous system (CNS). They consist of three layers: the dura mater, arachnoid mater, and pia mater. The meninges provide cushioning and support to the brain and spinal cord, protecting them from injury. They also help regulate the flow of cerebrospinal fluid (CSF), a clear fluid that surrounds and nourishes the CNS. Additionally, the meninges help maintain the stability and shape of the CNS within the skull and spinal column.

Explanation

The meninges are the layers of protective tissue surrounding the central nervous system (CNS). They consist of three layers: the dura mater, arachnoid mater, and pia mater. The meninges provide cushioning and support to the brain and spinal cord, protecting them from injury. They also help regulate the flow of cerebrospinal fluid (CSF), a clear fluid that surrounds and nourishes the CNS. Additionally, the meninges help maintain the stability and shape of the CNS within the skull and spinal column.

13. The recommended criteria for surgeon notification when monitoring BAEPs intraoperatively include an increase in

Latency of wave V of less than 1ms

Interpeak latency of I-V of

Absolute latency of wave I, without change in wave V

Latency of wave V of >1ms or the disappearance of wave V

The recommended criteria for surgeon notification when monitoring BAEPs intraoperatively include a latency of wave V of >1ms or the disappearance of wave V. This means that if the latency of wave V exceeds 1ms or if wave V completely disappears, the surgeon should be notified. This could indicate a potential issue or complication during the surgery that requires immediate attention.

Explanation

The recommended criteria for surgeon notification when monitoring BAEPs intraoperatively include a latency of wave V of >1ms or the disappearance of wave V. This means that if the latency of wave V exceeds 1ms or if wave V completely disappears, the surgeon should be notified. This could indicate a potential issue or complication during the surgery that requires immediate attention.

14. The patient presenting prior to surgery for removal of an acoustic neuroma would likely have symptoms including

Muscle weakness and gait disturbance

Slurred speech, aphasia, and focal weakness

Nystagmus and decreased visual acuity

Hearing loss, headaches, and unsteady gait

The correct answer is "Hearing loss, headaches, and unsteady gait." Acoustic neuroma is a tumor that develops on the nerve responsible for hearing and balance. As the tumor grows, it can cause hearing loss and tinnitus. Headaches may occur due to increased pressure in the skull. The tumor can also affect the balance, leading to an unsteady gait. Therefore, these symptoms are likely to be present in a patient with an acoustic neuroma prior to surgery.

Explanation

The correct answer is "Hearing loss, headaches, and unsteady gait." Acoustic neuroma is a tumor that develops on the nerve responsible for hearing and balance. As the tumor grows, it can cause hearing loss and tinnitus. Headaches may occur due to increased pressure in the skull. The tumor can also affect the balance, leading to an unsteady gait. Therefore, these symptoms are likely to be present in a patient with an acoustic neuroma prior to surgery.

15. The waveform labeled B is most likely

N5

N9

N11

N13

Waveform B is probably an Erb’s point potential coming in at N9

Explanation

Waveform B is probably an Erb’s point potential coming in at N9

16. The branches of the facial nerve include all except the:

Zygomatic

Buccal

Superior thyroid

Temporal

The superior thyroid branch is not a branch of the facial nerve. The facial nerve branches include the zygomatic, buccal, and temporal branches. The superior thyroid branch is actually a branch of the external carotid artery, not the facial nerve.

Explanation

The superior thyroid branch is not a branch of the facial nerve. The facial nerve branches include the zygomatic, buccal, and temporal branches. The superior thyroid branch is actually a branch of the external carotid artery, not the facial nerve.

17. What is considered criteria for alarm when monitoring BAERs intraoperatively?

Decreased latency of I-V

Increased I-V interpeak latency or loss of wave V

Decreased interpeak latency of waves I-V

Increased amplitude of wave V

When monitoring BAERs intraoperatively, the criteria for alarm is an increased I-V interpeak latency or loss of wave V. This means that there is a delay or absence of the wave V response compared to the wave I response, indicating a potential issue with the auditory pathway. This could be caused by damage or dysfunction in the auditory nerve or brainstem. Monitoring these criteria helps identify any abnormalities and allows for prompt intervention if necessary.

Explanation

When monitoring BAERs intraoperatively, the criteria for alarm is an increased I-V interpeak latency or loss of wave V. This means that there is a delay or absence of the wave V response compared to the wave I response, indicating a potential issue with the auditory pathway. This could be caused by damage or dysfunction in the auditory nerve or brainstem. Monitoring these criteria helps identify any abnormalities and allows for prompt intervention if necessary.

18. Du ring posterior fossa surgery, wave V of the BAEPs may increase in latency due to:

Spinal drainage

Warming of the nerve

Retraction of the cerebellum

Use of neuromuscular blocking agent

During posterior fossa surgery, the retraction of the cerebellum can cause an increase in latency of wave V of the BAEPs. This is because the retraction puts pressure on the brainstem, specifically the auditory pathway, which can lead to a delay in the conduction of the auditory signals. This delay is reflected in the increased latency of wave V.

Explanation

During posterior fossa surgery, the retraction of the cerebellum can cause an increase in latency of wave V of the BAEPs. This is because the retraction puts pressure on the brainstem, specifically the auditory pathway, which can lead to a delay in the conduction of the auditory signals. This delay is reflected in the increased latency of wave V.

19. If there is a 60Hz interference in all channels when recording median nerve somatosensory evoked potentials, which of the following electrodes should be adjusted first?

Cpi

Epc

Ground electrode

Stimulating electrode

The ground electrode should be adjusted first because it is responsible for providing a reference point for the recording of electrical signals. If there is a 60Hz interference in all channels, it suggests that the ground electrode may not be properly placed or connected, leading to the interference. By adjusting the ground electrode, the electrical reference point can be improved, potentially reducing or eliminating the interference in the recorded signals.

Explanation

The ground electrode should be adjusted first because it is responsible for providing a reference point for the recording of electrical signals. If there is a 60Hz interference in all channels, it suggests that the ground electrode may not be properly placed or connected, leading to the interference. By adjusting the ground electrode, the electrical reference point can be improved, potentially reducing or eliminating the interference in the recorded signals.

20. When stimulating cranial nerve 7, a bipolar stimulator may have an advantage over a monopolar stimulator by:

Presenting less risk

Requiring less current

Having greater specificity

Being less expensive

A bipolar stimulator may have an advantage over a monopolar stimulator when stimulating cranial nerve 7 because it offers greater specificity. This means that the bipolar stimulator can target and stimulate the specific area of the cranial nerve more accurately, resulting in more precise and effective stimulation. This specificity can lead to better outcomes and reduced risk of unintended stimulation of surrounding tissues or nerves.

Explanation

A bipolar stimulator may have an advantage over a monopolar stimulator when stimulating cranial nerve 7 because it offers greater specificity. This means that the bipolar stimulator can target and stimulate the specific area of the cranial nerve more accurately, resulting in more precise and effective stimulation. This specificity can lead to better outcomes and reduced risk of unintended stimulation of surrounding tissues or nerves.

21. Muscle relaxants inhibit the ability to monitor BAERs.

True

False

Muscle relaxants do not inhibit the ability to monitor BAERs. BAERs (Brainstem Auditory Evoked Responses) are electrical signals generated by the brain in response to sound stimulation. Muscle relaxants primarily affect skeletal muscles and do not directly interfere with the brain's ability to generate or monitor these signals. Therefore, the statement is false.

Explanation

Muscle relaxants do not inhibit the ability to monitor BAERs. BAERs (Brainstem Auditory Evoked Responses) are electrical signals generated by the brain in response to sound stimulation. Muscle relaxants primarily affect skeletal muscles and do not directly interfere with the brain's ability to generate or monitor these signals. Therefore, the statement is false.

22. Which muscle is innervated by the C5 nerve root?

Tricep

Pronator teres

Deltoid

Trapezius

The deltoid muscle is innervated by the C5 nerve root. The C5 nerve root originates from the cervical spine and supplies motor innervation to the deltoid muscle, which is responsible for shoulder abduction and flexion. Damage or compression of the C5 nerve root can result in weakness or paralysis of the deltoid muscle, leading to difficulty in raising the arm or performing overhead activities.

Explanation

The deltoid muscle is innervated by the C5 nerve root. The C5 nerve root originates from the cervical spine and supplies motor innervation to the deltoid muscle, which is responsible for shoulder abduction and flexion. Damage or compression of the C5 nerve root can result in weakness or paralysis of the deltoid muscle, leading to difficulty in raising the arm or performing overhead activities.

23. In obtaining post-incision preoperative baseline posterior tibial SSEPs, what is the best location for the ground electrode?

The arm

The calf

The mastoid

Sole of the foot

Should be between the site of stim and the first recording electrode. This is assuming that the first recording is from the pop fossa.

Explanation

Should be between the site of stim and the first recording electrode. This is assuming that the first recording is from the pop fossa.

24. Which of the following is the method for monitoring the facial nerve?

BAEPs

Blink reflex

Free run EMG

Visual observation of facial movement

Free run EMG is the method for monitoring the facial nerve. EMG stands for electromyography, which is a technique used to measure muscle activity. "Free run" refers to the continuous recording of spontaneous muscle activity without any external stimulus. By placing electrodes on the facial muscles, the electrical signals produced by the facial nerve can be detected and monitored using EMG. This method allows for real-time assessment of facial nerve function and can be used in various clinical settings, such as during facial nerve surgery or in the diagnosis of facial nerve disorders.

Explanation

Free run EMG is the method for monitoring the facial nerve. EMG stands for electromyography, which is a technique used to measure muscle activity. "Free run" refers to the continuous recording of spontaneous muscle activity without any external stimulus. By placing electrodes on the facial muscles, the electrical signals produced by the facial nerve can be detected and monitored using EMG. This method allows for real-time assessment of facial nerve function and can be used in various clinical settings, such as during facial nerve surgery or in the diagnosis of facial nerve disorders.

25. Name the opening between the brain and the spinal cord?

Thalamus

Foramen magnum

Foramen minimum

Afferent tract

The foramen magnum is the correct answer to the question. It is the opening located at the base of the skull that allows the spinal cord to connect with the brain. This opening is essential for the passage of nerves and blood vessels between the brain and the spinal cord. The thalamus is a different structure in the brain that is responsible for relaying sensory information. The options "foramen minimum" and "afferent tract" are not accurate terms related to the opening between the brain and the spinal cord.

Explanation

The foramen magnum is the correct answer to the question. It is the opening located at the base of the skull that allows the spinal cord to connect with the brain. This opening is essential for the passage of nerves and blood vessels between the brain and the spinal cord. The thalamus is a different structure in the brain that is responsible for relaying sensory information. The options "foramen minimum" and "afferent tract" are not accurate terms related to the opening between the brain and the spinal cord.

26. An electrode recording from Erb's point is placed

On the shoulder

2-3 cm above the clavicle

Over the trapezius muscle

At the axilla

The correct answer is 2-3 cm above the clavicle. This is the correct placement for an electrode recording from Erb's point. Placing the electrode at this location allows for accurate recording of the nerve conduction from the brachial plexus, which is located in this area. Placing the electrode on the shoulder, over the trapezius muscle, or at the axilla would not provide accurate recordings from Erb's point.

Explanation

The correct answer is 2-3 cm above the clavicle. This is the correct placement for an electrode recording from Erb's point. Placing the electrode at this location allows for accurate recording of the nerve conduction from the brachial plexus, which is located in this area. Placing the electrode on the shoulder, over the trapezius muscle, or at the axilla would not provide accurate recordings from Erb's point.

27. When monitoring facial nerve EMG, which of the following is an indicator of potential nerve damage?

Occasional burst of fibrillation potentials

Continuous train of neurotonic discharges

CMAP to direct stimulation

Occasional muscle fasciculations

Continuous train of neurotonic discharges is an indicator of potential nerve damage when monitoring facial nerve EMG. Neurotonic discharges refer to abnormal, continuous, and sustained muscle contractions caused by nerve hyperexcitability. This can be a sign of nerve dysfunction or injury, as the nerve is continuously firing signals to the muscle. Occasional bursts of fibrillation potentials, occasional muscle fasciculations, and CMAP to direct stimulation may also indicate nerve damage, but the continuous train of neurotonic discharges is the most specific indicator in this context.

Explanation

Continuous train of neurotonic discharges is an indicator of potential nerve damage when monitoring facial nerve EMG. Neurotonic discharges refer to abnormal, continuous, and sustained muscle contractions caused by nerve hyperexcitability. This can be a sign of nerve dysfunction or injury, as the nerve is continuously firing signals to the muscle. Occasional bursts of fibrillation potentials, occasional muscle fasciculations, and CMAP to direct stimulation may also indicate nerve damage, but the continuous train of neurotonic discharges is the most specific indicator in this context.

28. Clavicular, cervical and scalp sites are commonly used for recording

Posterior tibial potentials

Brainstem auditory evoked potenetials

Median nerve potentials

Popliteal fossa potentials

Clavicular, cervical, and scalp sites are commonly used for recording median nerve potentials. These sites are chosen because they provide optimal access to the median nerve and allow for accurate measurement of its electrical activity. By placing electrodes at these sites, healthcare professionals can detect and analyze the electrical signals generated by the median nerve, which can help diagnose and monitor conditions affecting this nerve.

Explanation

Clavicular, cervical, and scalp sites are commonly used for recording median nerve potentials. These sites are chosen because they provide optimal access to the median nerve and allow for accurate measurement of its electrical activity. By placing electrodes at these sites, healthcare professionals can detect and analyze the electrical signals generated by the median nerve, which can help diagnose and monitor conditions affecting this nerve.

29. For posterior tibial somatosensory evoked potentials, which of the following would be the best ipsilateral location for the ground electrode?

Arm

Calf

Mastiod

Sole of foot

The calf would be the best ipsilateral location for the ground electrode in posterior tibial somatosensory evoked potentials. This is because the calf is closer to the site of stimulation, which is the sole of the foot. Placing the ground electrode in the calf helps to minimize electrical interference and ensures accurate measurement of the somatosensory evoked potentials.

Explanation

The calf would be the best ipsilateral location for the ground electrode in posterior tibial somatosensory evoked potentials. This is because the calf is closer to the site of stimulation, which is the sole of the foot. Placing the ground electrode in the calf helps to minimize electrical interference and ensures accurate measurement of the somatosensory evoked potentials.

30. Cortical potentials will be most affected by which of the following agents?

Narcotics / Opiods

Barbituates

Inhalational Anesthetics

Neuromuscular blockers

Cortical potentials are electrical signals in the brain that are responsible for various cognitive functions. Inhalational anesthetics are known to have a significant effect on these potentials. They work by altering the activity of neurotransmitters and receptors in the brain, leading to a decrease in cortical activity and inducing a state of unconsciousness. This makes inhalational anesthetics the most likely agent to have a profound impact on cortical potentials compared to narcotics/opioids, barbiturates, and neuromuscular blockers.

Explanation

Cortical potentials are electrical signals in the brain that are responsible for various cognitive functions. Inhalational anesthetics are known to have a significant effect on these potentials. They work by altering the activity of neurotransmitters and receptors in the brain, leading to a decrease in cortical activity and inducing a state of unconsciousness. This makes inhalational anesthetics the most likely agent to have a profound impact on cortical potentials compared to narcotics/opioids, barbiturates, and neuromuscular blockers.

31. Impedance is expressed in:

Ohms

Coulombs

Microvolts

Amps

Impedance is a measure of opposition to the flow of electric current in a circuit. It is expressed in ohms, which is the unit of electrical resistance. Ohms represent the amount of resistance that a circuit presents to the flow of current. Therefore, the correct answer is Ohms.

Explanation

Impedance is a measure of opposition to the flow of electric current in a circuit. It is expressed in ohms, which is the unit of electrical resistance. Ohms represent the amount of resistance that a circuit presents to the flow of current. Therefore, the correct answer is Ohms.

32. Which of the following is characteristic of alternating click polarity?

Produces abnormal I-V latencies

Has no effect on wave I amplitude

Is recommended for testing premature infants

Cancels the stimulus artifact

Alternating click polarity refers to the technique of reversing the polarity of the click stimulus during auditory brainstem response (ABR) testing. This technique is used to cancel out the stimulus artifact, which is an electrical artifact that occurs in the ABR waveform due to the click stimulus. By canceling the stimulus artifact, the ABR waveform becomes clearer and more accurate, allowing for more precise interpretation of the test results. Therefore, the characteristic of alternating click polarity is that it cancels the stimulus artifact.

Explanation

Alternating click polarity refers to the technique of reversing the polarity of the click stimulus during auditory brainstem response (ABR) testing. This technique is used to cancel out the stimulus artifact, which is an electrical artifact that occurs in the ABR waveform due to the click stimulus. By canceling the stimulus artifact, the ABR waveform becomes clearer and more accurate, allowing for more precise interpretation of the test results. Therefore, the characteristic of alternating click polarity is that it cancels the stimulus artifact.

33. Which procedure may be done to reduce muscle spasticity?

Selective dorsal root rhizotomy

Mediolateral cordotomy

Dorsal column mapping

Spinal fusion

Selective dorsal root rhizotomy is a surgical procedure that may be done to reduce muscle spasticity. It involves cutting the sensory nerve fibers in the spinal cord that are responsible for transmitting abnormal signals to the muscles, thereby reducing the spasticity. This procedure is commonly performed in individuals with conditions such as cerebral palsy, where spasticity is a common symptom. By selectively targeting and cutting the specific nerve fibers causing the spasticity, selective dorsal root rhizotomy can help improve muscle control and reduce spasticity in affected individuals.

Explanation

Selective dorsal root rhizotomy is a surgical procedure that may be done to reduce muscle spasticity. It involves cutting the sensory nerve fibers in the spinal cord that are responsible for transmitting abnormal signals to the muscles, thereby reducing the spasticity. This procedure is commonly performed in individuals with conditions such as cerebral palsy, where spasticity is a common symptom. By selectively targeting and cutting the specific nerve fibers causing the spasticity, selective dorsal root rhizotomy can help improve muscle control and reduce spasticity in affected individuals.

34. Monitoring modality most likely affected by a large bolus of muscle relaxant is:

Subcortical SSEP

TcMEP

Cortical SSEP

EEG

A large bolus of muscle relaxant can affect the monitoring modality of tcMEP (transcranial motor evoked potentials). Muscle relaxants can cause a decrease or loss of muscle activity, which can result in a decrease or loss of motor responses measured by tcMEP. Subcortical SSEP (somatosensory evoked potentials), cortical SSEP, and EEG (electroencephalogram) are not directly affected by muscle relaxants and would not be as likely to be affected by a large bolus of muscle relaxant.

Explanation

A large bolus of muscle relaxant can affect the monitoring modality of tcMEP (transcranial motor evoked potentials). Muscle relaxants can cause a decrease or loss of muscle activity, which can result in a decrease or loss of motor responses measured by tcMEP. Subcortical SSEP (somatosensory evoked potentials), cortical SSEP, and EEG (electroencephalogram) are not directly affected by muscle relaxants and would not be as likely to be affected by a large bolus of muscle relaxant.

35. What is true about intramedullary spinal tumor resection?

Loss of vascular perfusion can lead to MEP changes during resection

Tumor resection can lead to MEP change due to axonal damage

Dissection through dorsal columns can lead to decrease in SSEPs

All of the above

During intramedullary spinal tumor resection, there can be a loss of vascular perfusion, which can lead to changes in motor evoked potentials (MEPs). Tumor resection can also cause axonal damage, resulting in MEP changes. Additionally, dissection through the dorsal columns can lead to a decrease in somatosensory evoked potentials (SSEPs). Therefore, all of the given options are true about intramedullary spinal tumor resection.

Explanation

During intramedullary spinal tumor resection, there can be a loss of vascular perfusion, which can lead to changes in motor evoked potentials (MEPs). Tumor resection can also cause axonal damage, resulting in MEP changes. Additionally, dissection through the dorsal columns can lead to a decrease in somatosensory evoked potentials (SSEPs). Therefore, all of the given options are true about intramedullary spinal tumor resection.

36. Clavicular, cervical and scalp sites are commonly used for recording:

Posterior tibial potentials

Brainstem auditory evoked potentials

Median nerve potentials

Popliteal fossa potentials

The clavicular, cervical, and scalp sites are commonly used for recording median nerve potentials. The median nerve is a major nerve in the upper limb that innervates the muscles of the forearm and hand. Recording its potentials can provide information about the electrical activity and function of the nerve. The clavicular, cervical, and scalp sites are chosen because they allow for accurate and reliable recording of the median nerve potentials.

Explanation

The clavicular, cervical, and scalp sites are commonly used for recording median nerve potentials. The median nerve is a major nerve in the upper limb that innervates the muscles of the forearm and hand. Recording its potentials can provide information about the electrical activity and function of the nerve. The clavicular, cervical, and scalp sites are chosen because they allow for accurate and reliable recording of the median nerve potentials.

37. Standard infection precautions are used:

When patient is known to have infectious disease

When blood or bodily fluids are present

On all patients

Only when blood is present

Standard infection precautions are used on all patients as a preventive measure to reduce the risk of spreading infectious diseases. These precautions include practices such as hand hygiene, wearing personal protective equipment, proper disposal of waste, and cleaning and disinfecting surfaces. By implementing these precautions universally, healthcare providers can minimize the transmission of infections, even in patients who may not show any symptoms or have a confirmed diagnosis. This approach ensures the safety of both healthcare workers and patients, promoting a healthier healthcare environment overall.

Explanation

Standard infection precautions are used on all patients as a preventive measure to reduce the risk of spreading infectious diseases. These precautions include practices such as hand hygiene, wearing personal protective equipment, proper disposal of waste, and cleaning and disinfecting surfaces. By implementing these precautions universally, healthcare providers can minimize the transmission of infections, even in patients who may not show any symptoms or have a confirmed diagnosis. This approach ensures the safety of both healthcare workers and patients, promoting a healthier healthcare environment overall.

38. In spinal surgery the primary purpose of the popliteal fossa recording electrode is to

Verify adequacy of stimulus

Limit current spread

Confirm amplifier integrity

Provide evidence of a muscle twitch

The popliteal fossa recording electrode is used in spinal surgery to verify the adequacy of stimulus. This means that it is used to ensure that the stimulus being delivered to the patient's nerves or muscles is sufficient and effective. By monitoring the response or twitch of the muscles through the recording electrode, surgeons can determine if the stimulus is producing the desired effect and adjust accordingly. This helps in ensuring the success and safety of the surgery.

Explanation

The popliteal fossa recording electrode is used in spinal surgery to verify the adequacy of stimulus. This means that it is used to ensure that the stimulus being delivered to the patient's nerves or muscles is sufficient and effective. By monitoring the response or twitch of the muscles through the recording electrode, surgeons can determine if the stimulus is producing the desired effect and adjust accordingly. This helps in ensuring the success and safety of the surgery.

39. Which cranial nerve is routed through the internal auditory meatus and controls hearing and equilibrium?

VIII

VII

VI

III

Cranial nerve VIII, also known as the vestibulocochlear nerve, is routed through the internal auditory meatus and is responsible for controlling both hearing and equilibrium. It carries sensory information from the cochlea (responsible for hearing) and the vestibular system (responsible for balance and equilibrium) to the brain. This nerve plays a crucial role in our ability to perceive sound and maintain our balance.

Explanation

Cranial nerve VIII, also known as the vestibulocochlear nerve, is routed through the internal auditory meatus and is responsible for controlling both hearing and equilibrium. It carries sensory information from the cochlea (responsible for hearing) and the vestibular system (responsible for balance and equilibrium) to the brain. This nerve plays a crucial role in our ability to perceive sound and maintain our balance.

40. Muscle relaxants should not be used when recording

Facial nerve CMAPs

SSEPs

EEG

BAEPs

Muscle relaxants should not be used when recording Facial nerve CMAPs because muscle activity is necessary to generate the compound muscle action potentials (CMAPs). Muscle relaxants inhibit muscle contractions, which would prevent the accurate measurement of the nerve's response. Therefore, the use of muscle relaxants would interfere with the recording of Facial nerve CMAPs.

Explanation

Muscle relaxants should not be used when recording Facial nerve CMAPs because muscle activity is necessary to generate the compound muscle action potentials (CMAPs). Muscle relaxants inhibit muscle contractions, which would prevent the accurate measurement of the nerve's response. Therefore, the use of muscle relaxants would interfere with the recording of Facial nerve CMAPs.

41. When stimulating cranial nerve 7, a bipolar stimulator may have an advantage over a monopolar stimulator by:

Presenting less risk

Requiring less current

Having greater specificity

Being less expensive

A bipolar stimulator may have an advantage over a monopolar stimulator when stimulating cranial nerve 7 because it offers greater specificity. This means that it can target and stimulate the specific area or nerve more accurately, resulting in more precise and effective stimulation. This can be beneficial in medical procedures or treatments that require precise targeting of cranial nerve 7.

Explanation

A bipolar stimulator may have an advantage over a monopolar stimulator when stimulating cranial nerve 7 because it offers greater specificity. This means that it can target and stimulate the specific area or nerve more accurately, resulting in more precise and effective stimulation. This can be beneficial in medical procedures or treatments that require precise targeting of cranial nerve 7.

42. Which of the following is a critical surgical event?

Drilling of burr hole in skull

Decorticating of vertebral elements

Placing of muscle plug in the internal auditory canal.

Resecting of tumor fragments during acoustic neuroma resection

Resecting of tumor fragments during acoustic neuroma resection is considered a critical surgical event because it involves the removal of tumor fragments from the internal auditory canal. Acoustic neuroma is a benign tumor that develops on the nerve responsible for balance and hearing, and its resection is a complex surgical procedure. Resecting the tumor fragments requires precision and care to avoid damaging the surrounding nerves and structures. Any complications during this procedure can have significant consequences for the patient's hearing and balance functions. Therefore, it is crucial to consider this as a critical surgical event.

Explanation

Resecting of tumor fragments during acoustic neuroma resection is considered a critical surgical event because it involves the removal of tumor fragments from the internal auditory canal. Acoustic neuroma is a benign tumor that develops on the nerve responsible for balance and hearing, and its resection is a complex surgical procedure. Resecting the tumor fragments requires precision and care to avoid damaging the surrounding nerves and structures. Any complications during this procedure can have significant consequences for the patient's hearing and balance functions. Therefore, it is crucial to consider this as a critical surgical event.

43. Which of the following temperatures should be annotated as being hypothermic?

34 degrees Celsius

36 degrees Celsius

37 degrees Celsius

38 degrees Celsius

A temperature of 34 degrees Celsius should be annotated as being hypothermic because it is below the normal body temperature range of 36.5-37.5 degrees Celsius. Hypothermia occurs when the body loses heat faster than it can produce, leading to a dangerously low body temperature.

Explanation

A temperature of 34 degrees Celsius should be annotated as being hypothermic because it is below the normal body temperature range of 36.5-37.5 degrees Celsius. Hypothermia occurs when the body loses heat faster than it can produce, leading to a dangerously low body temperature.

44. The waveform labeled A is most likely generated by the

Cortex

Brainstem

Cervical spine

Brachial plexus

The waveform labeled A is most likely generated by the Cortex because the Cortex is responsible for higher cognitive functions such as perception, memory, and consciousness. It is the outer layer of the brain and contains billions of neurons that communicate through electrical signals, which can be detected as waveforms. The other options, such as the brainstem, cervical spine, and brachial plexus, are not involved in generating such complex cognitive functions and would not produce the waveform seen in A.

Explanation

The waveform labeled A is most likely generated by the Cortex because the Cortex is responsible for higher cognitive functions such as perception, memory, and consciousness. It is the outer layer of the brain and contains billions of neurons that communicate through electrical signals, which can be detected as waveforms. The other options, such as the brainstem, cervical spine, and brachial plexus, are not involved in generating such complex cognitive functions and would not produce the waveform seen in A.

45. The Popliteal Fossa and Erb's Point potentials can be used to:

Verify adequacy of stimulus

Assess the integrity of the dorsal columns

Assess the integrity of the DREZ

Test the neuromuscular junction

Pop fossa and erb’s point potentials can be used to verify the stimulus. Think about if you are monitoring a lumbar fusion and you lost your right lower extremity subcortical and cortical SSEP waveforms…. If you have a right pop fossa response, you can at least verify quickly that your stimulus is reaching the body and that the issue is likely in the region of the surgery.

Explanation

Pop fossa and erb’s point potentials can be used to verify the stimulus. Think about if you are monitoring a lumbar fusion and you lost your right lower extremity subcortical and cortical SSEP waveforms…. If you have a right pop fossa response, you can at least verify quickly that your stimulus is reaching the body and that the issue is likely in the region of the surgery.

46. Examples of surgical manipulation would include

Blood pressure and heart rate fluctuations

Core temperature changes

Oxygenation and ventilation changes

Drilling and irrigation

Surgical manipulation refers to the various techniques and procedures used during surgery to manipulate tissues or organs. In this context, drilling and irrigation are examples of surgical manipulation. Drilling involves using a drill to create holes in bones or other hard tissues, while irrigation involves flushing a surgical site with a sterile solution to clean and remove debris. These techniques are commonly used in orthopedic, dental, and other surgical procedures to prepare the site for further interventions or to facilitate the surgical process.

Explanation

Surgical manipulation refers to the various techniques and procedures used during surgery to manipulate tissues or organs. In this context, drilling and irrigation are examples of surgical manipulation. Drilling involves using a drill to create holes in bones or other hard tissues, while irrigation involves flushing a surgical site with a sterile solution to clean and remove debris. These techniques are commonly used in orthopedic, dental, and other surgical procedures to prepare the site for further interventions or to facilitate the surgical process.

47. Which cranial nerve is most appropriate to monitor during resection of a 4cm vestibular schwannoma?

Optic

Facial

Abducens

Oculomotor

During the resection of a 4cm vestibular schwannoma, monitoring the facial nerve is the most appropriate. The facial nerve is responsible for the movement of the muscles of the face, including the muscles involved in facial expressions. Resection of the schwannoma can potentially damage the facial nerve, leading to facial weakness or paralysis. Therefore, monitoring the facial nerve during the surgery is crucial to ensure its integrity and prevent any postoperative complications.

Explanation

During the resection of a 4cm vestibular schwannoma, monitoring the facial nerve is the most appropriate. The facial nerve is responsible for the movement of the muscles of the face, including the muscles involved in facial expressions. Resection of the schwannoma can potentially damage the facial nerve, leading to facial weakness or paralysis. Therefore, monitoring the facial nerve during the surgery is crucial to ensure its integrity and prevent any postoperative complications.

48. In which of the following is the sampling rate of an averager at least twice the frequency fo the fastest sine wave compoenent in the signal to be resolved?

Ohm's Law

Wiener filtering

Nyquist frequency

Fourier analysis

The Nyquist frequency is the maximum frequency that can be accurately represented in a sampled signal. According to the Nyquist-Shannon sampling theorem, the sampling rate must be at least twice the frequency of the highest frequency component in the signal in order to avoid aliasing and accurately reconstruct the original signal. Therefore, the correct answer is Nyquist frequency.

Explanation

The Nyquist frequency is the maximum frequency that can be accurately represented in a sampled signal. According to the Nyquist-Shannon sampling theorem, the sampling rate must be at least twice the frequency of the highest frequency component in the signal in order to avoid aliasing and accurately reconstruct the original signal. Therefore, the correct answer is Nyquist frequency.

49. How will halogenated gases affect cortical SSEPs?

Decrease latency, decrease amplitude

Increase latency, decrease amplitude

Negligible affects

Increase latency, increase amplitude

Halogenated gases are known to have an inhibitory effect on the central nervous system. When these gases are administered, they can cause a delay in the transmission of signals from the sensory cortex to the brain, leading to an increase in latency. Additionally, these gases can also reduce the amplitude of the cortical somatosensory evoked potentials (SSEPs), which are electrical responses generated by the brain in response to sensory stimulation. Therefore, the correct answer is that halogenated gases will increase latency and decrease amplitude of cortical SSEPs.

Explanation

Halogenated gases are known to have an inhibitory effect on the central nervous system. When these gases are administered, they can cause a delay in the transmission of signals from the sensory cortex to the brain, leading to an increase in latency. Additionally, these gases can also reduce the amplitude of the cortical somatosensory evoked potentials (SSEPs), which are electrical responses generated by the brain in response to sensory stimulation. Therefore, the correct answer is that halogenated gases will increase latency and decrease amplitude of cortical SSEPs.

50. Somatosensory Evoked Potential

Ventral root

Choroid plexus

Dorsal root

Anterior horn cell

The dorsal root is the correct answer because it is a part of the spinal nerve that carries sensory information from the body to the central nervous system. The somatosensory evoked potential refers to the electrical response generated by the sensory pathways in response to a sensory stimulus. Therefore, the dorsal root is involved in transmitting sensory information, making it the most appropriate choice among the given options.

Explanation

The dorsal root is the correct answer because it is a part of the spinal nerve that carries sensory information from the body to the central nervous system. The somatosensory evoked potential refers to the electrical response generated by the sensory pathways in response to a sensory stimulus. Therefore, the dorsal root is involved in transmitting sensory information, making it the most appropriate choice among the given options.

51. Masking:

Eliminates wave I

Eliminates cross over response via bone conduction

Enhances wave V

Enhances wave III

The process of masking in audiology involves using noise to eliminate or suppress the response from one ear, allowing the response from the other ear to be measured separately. In this case, the answer suggests that masking is used to eliminate the cross over response via bone conduction. This means that the noise is used to prevent the sound from being conducted through the bones of the skull and reaching the opposite ear, ensuring that only the response from the intended ear is measured.

Explanation

The process of masking in audiology involves using noise to eliminate or suppress the response from one ear, allowing the response from the other ear to be measured separately. In this case, the answer suggests that masking is used to eliminate the cross over response via bone conduction. This means that the noise is used to prevent the sound from being conducted through the bones of the skull and reaching the opposite ear, ensuring that only the response from the intended ear is measured.

52. Hypothermia

Has no effect on evoked potential latencies

Decreases evoked potential latencies

Increases evoked potential latencies

A variable effect on evoked potential latency

Hypothermia refers to a condition where the body's core temperature drops below normal levels. This can have various effects on the body, including a delay in nerve conduction. Evoked potentials are electrical signals generated by the nervous system in response to stimuli, and their latencies refer to the time it takes for these signals to travel along the nerves. Hypothermia can slow down nerve conduction, leading to an increase in evoked potential latencies. Therefore, the correct answer is that hypothermia increases evoked potential latencies.

Explanation

Hypothermia refers to a condition where the body's core temperature drops below normal levels. This can have various effects on the body, including a delay in nerve conduction. Evoked potentials are electrical signals generated by the nervous system in response to stimuli, and their latencies refer to the time it takes for these signals to travel along the nerves. Hypothermia can slow down nerve conduction, leading to an increase in evoked potential latencies. Therefore, the correct answer is that hypothermia increases evoked potential latencies.

53. The nerve root entry levels for PTN are?

C5-T1

L1-L4

L4-S3

S1-S5

The correct answer is L4-S3. This is because PTN (pudendal nerve) originates from the nerve roots L4-S3. The nerve roots C5-T1 are associated with the brachial plexus, which is not relevant to PTN. Similarly, S1-S5 are not the correct nerve root entry levels for PTN. Therefore, the correct answer is L4-S3.

Explanation

The correct answer is L4-S3. This is because PTN (pudendal nerve) originates from the nerve roots L4-S3. The nerve roots C5-T1 are associated with the brachial plexus, which is not relevant to PTN. Similarly, S1-S5 are not the correct nerve root entry levels for PTN. Therefore, the correct answer is L4-S3.

54. Which of the following drugs will affect EMG signals?

Pentothal

Forane

Vecuronium

Versed

Pentothal: ultra-short acting barbiturate- induction but has been largely replaced by propofol

Forane: this is isoflurane, inhalational agent thus no effect on muscles

Vecuronium: non-depolarizing paralytic

Versed: aka midazolam. Benzodiazapine- anti anxiety, produces sleepiness, helps produce amnesia

Explanation

Pentothal: ultra-short acting barbiturate- induction but has been largely replaced by propofol

Forane: this is isoflurane, inhalational agent thus no effect on muscles

Vecuronium: non-depolarizing paralytic

Versed: aka midazolam. Benzodiazapine- anti anxiety, produces sleepiness, helps produce amnesia

55. What nerve innervates most of the flexors in the forearm and supplies sensory distribution to the thumb, index, and middle finger?

Median

Ulnar

Posterior tibial

CN VIII

The median nerve innervates most of the flexors in the forearm and supplies sensory distribution to the thumb, index, and middle finger.

Explanation

The median nerve innervates most of the flexors in the forearm and supplies sensory distribution to the thumb, index, and middle finger.

56. Troubleshooting in the OR is facilitated by:

Activating the 60hz filter

Viewing raw data input

Increasing the high frequency filter

Decreasing the high frequency filter

Because you can determine the type of artifact that is interfering by looking at the raw, non-amplified data. Is it EMG artifact? Is it 60 cycle?

Explanation

Because you can determine the type of artifact that is interfering by looking at the raw, non-amplified data. Is it EMG artifact? Is it 60 cycle?

57. Proper sterilant/disinfectant procedure for high level sterilization?

Wash for 30 to 60 seconds

Liquid immersion in bleach for 20 mins

Discard in sharps container

Wipe of with clean towel

The proper sterilant/disinfectant procedure for high-level sterilization involves immersing the object in a liquid bleach solution for 20 minutes. This is because bleach is a strong disinfectant that can effectively kill a wide range of microorganisms. The 20-minute immersion allows enough time for the bleach to thoroughly disinfect the object. Other steps mentioned, such as washing for 30 to 60 seconds, discarding in a sharps container, and wiping off with a clean towel, may be part of a broader sterilization process but are not specifically mentioned in the question.

Explanation

The proper sterilant/disinfectant procedure for high-level sterilization involves immersing the object in a liquid bleach solution for 20 minutes. This is because bleach is a strong disinfectant that can effectively kill a wide range of microorganisms. The 20-minute immersion allows enough time for the bleach to thoroughly disinfect the object. Other steps mentioned, such as washing for 30 to 60 seconds, discarding in a sharps container, and wiping off with a clean towel, may be part of a broader sterilization process but are not specifically mentioned in the question.

58. Which of the following is a common complication of microvascular decompression of cranial nerve VII?

Visual loss

Hearing loss

Lower extremity weakness

Upper extremity weakness

Microvascular decompression of cranial nerve VII is a surgical procedure used to treat trigeminal neuralgia. During the procedure, the surgeon places a cushion between the nerve and the blood vessel causing compression. While hearing loss is not a common complication of this surgery, it can occur due to injury to the cochlear nerve, which is located near cranial nerve VII. The other options, visual loss, lower extremity weakness, and upper extremity weakness, are not typically associated with this procedure.

Explanation

Microvascular decompression of cranial nerve VII is a surgical procedure used to treat trigeminal neuralgia. During the procedure, the surgeon places a cushion between the nerve and the blood vessel causing compression. While hearing loss is not a common complication of this surgery, it can occur due to injury to the cochlear nerve, which is located near cranial nerve VII. The other options, visual loss, lower extremity weakness, and upper extremity weakness, are not typically associated with this procedure.

59. Which of the following refers to the phenomenon of fast frequency components of an artifact or signal showing up on an evoked potential at slower frequencies?

Delay

Smoothing

Aliasing

Anodal Blocking

Aliasing refers to the phenomenon where fast frequency components of an artifact or signal appear as slower frequencies on an evoked potential. This occurs when the sampling rate of the signal is too low to accurately represent the higher frequency components, causing them to be misrepresented as lower frequencies.

Explanation

Aliasing refers to the phenomenon where fast frequency components of an artifact or signal appear as slower frequencies on an evoked potential. This occurs when the sampling rate of the signal is too low to accurately represent the higher frequency components, causing them to be misrepresented as lower frequencies.

60. In what age group do early symptoms of multiple sclerosis usually occur?

Under 10 years

15-40 years

50-60 years

Over5 70 years

Early symptoms of multiple sclerosis usually occur in the age group of 15-40 years. This is the most common age range for the onset of multiple sclerosis, although it can occur at any age. The symptoms may vary from person to person but commonly include fatigue, difficulty walking, numbness or tingling in the limbs, muscle weakness, and problems with coordination and balance. It is important to note that these symptoms can also be caused by other conditions, so a proper diagnosis by a healthcare professional is necessary.

Explanation

Early symptoms of multiple sclerosis usually occur in the age group of 15-40 years. This is the most common age range for the onset of multiple sclerosis, although it can occur at any age. The symptoms may vary from person to person but commonly include fatigue, difficulty walking, numbness or tingling in the limbs, muscle weakness, and problems with coordination and balance. It is important to note that these symptoms can also be caused by other conditions, so a proper diagnosis by a healthcare professional is necessary.

61. Voltage information is changed into numerical values for averaging by means of

Analog to analog conversion

Digital to digital conversion

Analog to digital conversion

Digital to analog conversion

Analog to digital conversion is the process of converting continuous analog signals into discrete digital values. In the context of the given question, voltage information is being converted into numerical values for averaging. This process involves sampling the analog signal at regular intervals and quantizing the sampled values into digital codes. By converting the voltage information into digital values, it becomes easier to manipulate and process the data, such as averaging the values. Therefore, analog to digital conversion is the correct answer in this case.

Explanation

Analog to digital conversion is the process of converting continuous analog signals into discrete digital values. In the context of the given question, voltage information is being converted into numerical values for averaging. This process involves sampling the analog signal at regular intervals and quantizing the sampled values into digital codes. By converting the voltage information into digital values, it becomes easier to manipulate and process the data, such as averaging the values. Therefore, analog to digital conversion is the correct answer in this case.

62. The cranial nerves responsible for eye movement are

II, III, and VII

III only

III, IV, and VI

II, VII, and IX

The cranial nerves responsible for eye movement are the third (oculomotor), fourth (trochlear), and sixth (abducens) cranial nerves. The oculomotor nerve controls most of the eye movements, including raising the eyelid, moving the eye up, down, and medially, and controlling the size of the pupil. The trochlear nerve controls the superior oblique muscle, which is responsible for moving the eye downward and outward. The abducens nerve controls the lateral rectus muscle, which is responsible for moving the eye laterally. Therefore, the correct answer is III, IV, and VI.

Explanation

The cranial nerves responsible for eye movement are the third (oculomotor), fourth (trochlear), and sixth (abducens) cranial nerves. The oculomotor nerve controls most of the eye movements, including raising the eyelid, moving the eye up, down, and medially, and controlling the size of the pupil. The trochlear nerve controls the superior oblique muscle, which is responsible for moving the eye downward and outward. The abducens nerve controls the lateral rectus muscle, which is responsible for moving the eye laterally. Therefore, the correct answer is III, IV, and VI.

63. The Queen's Square, uses a naming convention of MF (12 cm above nasion), MO (5 cm above inion), LO 5 cm left of MO, RO 5 cm right of MO, and A1 on the left ear lobe and ground or common on Cz.

True

False

The given statement is true. The Queen's Square uses a specific naming convention for electrode placements. MF refers to a point 12 cm above the nasion (the bridge of the nose), MO refers to a point 5 cm above the inion (the external occipital protuberance at the back of the skull), LO refers to a point 5 cm to the left of MO, RO refers to a point 5 cm to the right of MO, A1 refers to the left ear lobe, and common or ground is placed on Cz (a specific location on the scalp). This naming convention helps in accurately identifying the placement of electrodes during neurophysiological studies.

Explanation

The given statement is true. The Queen's Square uses a specific naming convention for electrode placements. MF refers to a point 12 cm above the nasion (the bridge of the nose), MO refers to a point 5 cm above the inion (the external occipital protuberance at the back of the skull), LO refers to a point 5 cm to the left of MO, RO refers to a point 5 cm to the right of MO, A1 refers to the left ear lobe, and common or ground is placed on Cz (a specific location on the scalp). This naming convention helps in accurately identifying the placement of electrodes during neurophysiological studies.

64. What is the function of spinal musculature and ligaments?

The reflex arc

Bowel and bladder function

Sensation and proprioception

Motion and protection

The spinal musculature and ligaments play a crucial role in providing motion and protection to the spine. The muscles of the spine, such as the erector spinae and the deep intrinsic muscles, allow for movement and stability of the spine. They help in maintaining posture, supporting the weight of the body, and enabling various movements such as bending, twisting, and extending the spine. Additionally, the ligaments of the spine provide stability and protect the spinal cord and nerves from excessive movements and injuries.

Explanation

The spinal musculature and ligaments play a crucial role in providing motion and protection to the spine. The muscles of the spine, such as the erector spinae and the deep intrinsic muscles, allow for movement and stability of the spine. They help in maintaining posture, supporting the weight of the body, and enabling various movements such as bending, twisting, and extending the spine. Additionally, the ligaments of the spine provide stability and protect the spinal cord and nerves from excessive movements and injuries.

65. One effect of ketamine on the SSEP is:

Increase amplitude

Decrease latency

Decrease amplitude

Increase latency

Ketamine is a dissociative anesthetic that can affect the sensory evoked potentials (SSEP). SSEP measures the electrical activity in the brain in response to sensory stimulation. An increase in amplitude indicates a stronger signal or response from the sensory stimulation. Therefore, the effect of ketamine on SSEP is to increase the amplitude of the evoked potentials.

Explanation

Ketamine is a dissociative anesthetic that can affect the sensory evoked potentials (SSEP). SSEP measures the electrical activity in the brain in response to sensory stimulation. An increase in amplitude indicates a stronger signal or response from the sensory stimulation. Therefore, the effect of ketamine on SSEP is to increase the amplitude of the evoked potentials.

66. Which of the following will cause burst suppression on the EEG?

Succinylcholine chloride

Propofol

Loss of ground electrode

Decrease in inhalational anesthetics

Propofol administration can cause burst suppression on the EEG. Burst suppression is a pattern characterized by alternating periods of high-amplitude bursts of electrical activity followed by periods of electrical silence. Propofol is a commonly used intravenous anesthetic that acts as a GABA agonist, enhancing inhibitory neurotransmission in the brain. This leads to a profound suppression of neuronal activity, resulting in burst suppression on the EEG. The other options, succinylcholine chloride, loss of ground electrode, and decrease in inhalational anesthetics, do not typically cause burst suppression on the EEG.

Explanation

Propofol administration can cause burst suppression on the EEG. Burst suppression is a pattern characterized by alternating periods of high-amplitude bursts of electrical activity followed by periods of electrical silence. Propofol is a commonly used intravenous anesthetic that acts as a GABA agonist, enhancing inhibitory neurotransmission in the brain. This leads to a profound suppression of neuronal activity, resulting in burst suppression on the EEG. The other options, succinylcholine chloride, loss of ground electrode, and decrease in inhalational anesthetics, do not typically cause burst suppression on the EEG.

67. During a posterior fossa approach for removal of an acoustic neuroma, an increase in the latency of wave V is most likely caused by

Fluid in the ear canal

Retraction of the cerebellum

Failure to stimulate

A loss of blood supply to the cochlea

Posterior fossa approach is approaching the lower brainstem area, and the cerebellum will most always need to be retracted, which is the most common cause of wave V increases in latency.

Explanation

Posterior fossa approach is approaching the lower brainstem area, and the cerebellum will most always need to be retracted, which is the most common cause of wave V increases in latency.

68. Lateral hemi-section of the cord producing ipsilateral loss of motor function, contralateral loss of major sensory function, below level of injury:

Parkinsons disease

Brown-sequard syndrom

Sturge-weber syndrom

Babinski

Brown-Sequard syndrome is a neurological condition caused by a lateral hemi-section of the spinal cord. This injury results in ipsilateral (same side) loss of motor function and contralateral (opposite side) loss of major sensory function below the level of injury. Parkinson's disease is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia, but it does not involve a hemi-section of the spinal cord. Sturge-Weber syndrome is a rare congenital disorder that affects the skin and brain, causing symptoms like seizures and intellectual disability, but it does not result in the specific motor and sensory deficits described. Babinski reflex is a clinical sign used to test for upper motor neuron dysfunction and is not related to the given symptoms.

Explanation

Brown-Sequard syndrome is a neurological condition caused by a lateral hemi-section of the spinal cord. This injury results in ipsilateral (same side) loss of motor function and contralateral (opposite side) loss of major sensory function below the level of injury. Parkinson's disease is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia, but it does not involve a hemi-section of the spinal cord. Sturge-Weber syndrome is a rare congenital disorder that affects the skin and brain, causing symptoms like seizures and intellectual disability, but it does not result in the specific motor and sensory deficits described. Babinski reflex is a clinical sign used to test for upper motor neuron dysfunction and is not related to the given symptoms.

69. Motor Threshold

Minimum stimulus intensity that results in a twitch in the appropriate muscle group

The level at which stimulation is first felt

Two times sensory threshold

The level which the patient is able to relax and tolerate the stimulus

The motor threshold refers to the minimum stimulus intensity required to elicit a twitch in the appropriate muscle group. This means that when the stimulus reaches this intensity, it is able to activate the muscles and cause a visible twitch. It is not related to the level at which stimulation is first felt or the patient's ability to relax and tolerate the stimulus. The motor threshold specifically focuses on the muscle response to the stimulus.

Explanation

The motor threshold refers to the minimum stimulus intensity required to elicit a twitch in the appropriate muscle group. This means that when the stimulus reaches this intensity, it is able to activate the muscles and cause a visible twitch. It is not related to the level at which stimulation is first felt or the patient's ability to relax and tolerate the stimulus. The motor threshold specifically focuses on the muscle response to the stimulus.

70. N2O GENERATOR

Peripheral nerve

Dorsal columns

Spinomedullary junction

Sensory cortex

The question is asking for the correct answer related to the N2O generator. The options given are peripheral nerve, dorsal columns, spinomedullary junction, and sensory cortex. Out of these options, the sensory cortex is the most relevant answer as it is a part of the brain responsible for processing sensory information. The other options do not directly relate to the N2O generator. Therefore, the correct answer is sensory cortex.

Explanation

The question is asking for the correct answer related to the N2O generator. The options given are peripheral nerve, dorsal columns, spinomedullary junction, and sensory cortex. Out of these options, the sensory cortex is the most relevant answer as it is a part of the brain responsible for processing sensory information. The other options do not directly relate to the N2O generator. Therefore, the correct answer is sensory cortex.

71. According to MacDonald, what is the primary patient safety concern regarding tcMEP stimulation?

Pacemaker damage

Seizure induction

Patient movement

Tongue bite

Basically, A and B are theoretical risks, but are rare if ever occurring. Patient movement is an issue, however not a safety concern especially if asking permission before running one so surgeon can make sure clear of site. Tongue or lip injury is the most common occurrence and is a real safety concern.

Explanation

Basically, A and B are theoretical risks, but are rare if ever occurring. Patient movement is an issue, however not a safety concern especially if asking permission before running one so surgeon can make sure clear of site. Tongue or lip injury is the most common occurrence and is a real safety concern.

72. To monitor CN XI, needles should be placed:

In the orbicularis oculi muscle

In the orbicularis oris muscle

In the sternocleidomastoid

In the platysma muscle

The correct answer is "in the sternocleidomastoid." CN XI, also known as the spinal accessory nerve, innervates the sternocleidomastoid muscle. This muscle is responsible for the rotation and flexion of the head and neck. By placing needles in the sternocleidomastoid muscle, one can effectively monitor the function of CN XI. Needles placed in the other muscles mentioned (orbicularis oculi, orbicularis oris, and platysma) would not provide accurate monitoring of CN XI.

Explanation

The correct answer is "in the sternocleidomastoid." CN XI, also known as the spinal accessory nerve, innervates the sternocleidomastoid muscle. This muscle is responsible for the rotation and flexion of the head and neck. By placing needles in the sternocleidomastoid muscle, one can effectively monitor the function of CN XI. Needles placed in the other muscles mentioned (orbicularis oculi, orbicularis oris, and platysma) would not provide accurate monitoring of CN XI.

73. Monitoring of the cranial nerve IX can be done by placing electrodes in the

Mentalis

Soft palate

Masseter

Trapezius

The correct answer is the soft palate. Monitoring of cranial nerve IX, also known as the glossopharyngeal nerve, can be done by placing electrodes on the soft palate. This nerve is responsible for controlling the muscles of the throat and tongue, as well as providing sensory information from the back of the throat and the taste buds. By monitoring the activity of the soft palate, healthcare professionals can assess the function of cranial nerve IX and detect any abnormalities or dysfunctions.

Explanation

The correct answer is the soft palate. Monitoring of cranial nerve IX, also known as the glossopharyngeal nerve, can be done by placing electrodes on the soft palate. This nerve is responsible for controlling the muscles of the throat and tongue, as well as providing sensory information from the back of the throat and the taste buds. By monitoring the activity of the soft palate, healthcare professionals can assess the function of cranial nerve IX and detect any abnormalities or dysfunctions.

74. During a posterior fossa resection of acoustic neuroma surgery, you observe the loss of a single wave (wave II) of the BAER. What should you do?

Inform the surgeon. This indicates significant damage to the VIIIth nerve.

Check the contralateral BAER to confirm a lesion in the pons.

Continue to monitor without alarm.

Check anesthetic levels.

Loss of a single wave (wave II) of the BAER during a posterior fossa resection of acoustic neuroma surgery does not necessarily indicate significant damage to the VIIIth nerve. It could be a temporary change due to surgical manipulation or anesthesia. Continuing to monitor without alarm allows for further observation to determine if the loss of wave II persists or if it recovers. If it persists or if there are other concerning signs, then further action can be taken. Checking the contralateral BAER or anesthetic levels may be done if there are additional symptoms or concerns, but it is not necessary at this point.

Explanation

Loss of a single wave (wave II) of the BAER during a posterior fossa resection of acoustic neuroma surgery does not necessarily indicate significant damage to the VIIIth nerve. It could be a temporary change due to surgical manipulation or anesthesia. Continuing to monitor without alarm allows for further observation to determine if the loss of wave II persists or if it recovers. If it persists or if there are other concerning signs, then further action can be taken. Checking the contralateral BAER or anesthetic levels may be done if there are additional symptoms or concerns, but it is not necessary at this point.

75. Direct stimulation of the motor branch of cranial nerve V will result in

Lateral eye movement

Jaw movement

Decrease in heart rate

Tongue movement

Direct stimulation of the motor branch of cranial nerve V, also known as the trigeminal nerve, will result in jaw movement. The trigeminal nerve is responsible for the motor function of the muscles involved in chewing and biting. When this nerve is stimulated, it causes the muscles of the jaw to contract, resulting in movement of the jaw. Therefore, the correct answer is jaw movement.

Explanation

Direct stimulation of the motor branch of cranial nerve V, also known as the trigeminal nerve, will result in jaw movement. The trigeminal nerve is responsible for the motor function of the muscles involved in chewing and biting. When this nerve is stimulated, it causes the muscles of the jaw to contract, resulting in movement of the jaw. Therefore, the correct answer is jaw movement.

76. Which of the following would best enhance resolution of evoked potential waveforms?

Decrease sensitivity

Decrease filter band width

Increase stimulation rate

Increase number of averaged stimuli

Increasing the number of averaged stimuli would best enhance the resolution of evoked potential waveforms. Averaging multiple stimuli helps to reduce random noise and increase the signal-to-noise ratio, resulting in a clearer and more reliable waveform. By increasing the number of averaged stimuli, any random variations can be averaged out, allowing the true response to be more easily detected and enhancing the resolution of the waveform.

Explanation

Increasing the number of averaged stimuli would best enhance the resolution of evoked potential waveforms. Averaging multiple stimuli helps to reduce random noise and increase the signal-to-noise ratio, resulting in a clearer and more reliable waveform. By increasing the number of averaged stimuli, any random variations can be averaged out, allowing the true response to be more easily detected and enhancing the resolution of the waveform.

77. Masking is recommended to eliminate

Asymmetry in latency and amplitude

False negative from the ipsilateral ear

Bone-conducted responses from the "non-stimulated" ear

False positive from the ipsilateral ear

Masking is recommended to eliminate bone-conducted responses from the "non-stimulated" ear. Bone-conducted responses occur when sound vibrations are transmitted through the bones of the skull and directly stimulate the cochlea, bypassing the outer and middle ear. When conducting audiometry tests, it is important to ensure that the responses being measured are only from the ear being tested, and not from any other sources. By using masking, which involves presenting a noise in the non-stimulated ear, any bone-conducted responses from that ear are effectively masked or blocked out, allowing for accurate measurement of the responses from the stimulated ear.

Explanation

Masking is recommended to eliminate bone-conducted responses from the "non-stimulated" ear. Bone-conducted responses occur when sound vibrations are transmitted through the bones of the skull and directly stimulate the cochlea, bypassing the outer and middle ear. When conducting audiometry tests, it is important to ensure that the responses being measured are only from the ear being tested, and not from any other sources. By using masking, which involves presenting a noise in the non-stimulated ear, any bone-conducted responses from that ear are effectively masked or blocked out, allowing for accurate measurement of the responses from the stimulated ear.

78. Which of the following would best enhance resolution of evoked potential waveforms?

Decrease sensitivity

Decrease filter band width

Increase stimulation rate

Increase number of averaged stimuli

Increasing the number of averaged stimuli would best enhance the resolution of evoked potential waveforms. Averaging multiple stimuli helps to reduce background noise and increase the signal-to-noise ratio, resulting in clearer and more accurate waveforms. By increasing the number of averaged stimuli, any random variations or noise in the measurements can be minimized, allowing for a more reliable and precise representation of the evoked potentials. This enhancement in resolution can aid in better understanding and analysis of the underlying neural activity.

Explanation

Increasing the number of averaged stimuli would best enhance the resolution of evoked potential waveforms. Averaging multiple stimuli helps to reduce background noise and increase the signal-to-noise ratio, resulting in clearer and more accurate waveforms. By increasing the number of averaged stimuli, any random variations or noise in the measurements can be minimized, allowing for a more reliable and precise representation of the evoked potentials. This enhancement in resolution can aid in better understanding and analysis of the underlying neural activity.

79. Which of the following cranial nerves is purely sensory?

III

VI

VIII

XI

Cranial nerve VIII, also known as the vestibulocochlear nerve, is purely sensory. It is responsible for transmitting auditory and vestibular information from the inner ear to the brain. This nerve plays a crucial role in hearing and balance. Cranial nerves III, VI, and XI have both sensory and motor functions, making VIII the only correct answer.

Explanation

Cranial nerve VIII, also known as the vestibulocochlear nerve, is purely sensory. It is responsible for transmitting auditory and vestibular information from the inner ear to the brain. This nerve plays a crucial role in hearing and balance. Cranial nerves III, VI, and XI have both sensory and motor functions, making VIII the only correct answer.

80. Harrington instrumentation

Pedicle screws

Sublaminar wires

Rods

Interbody grafts

Rods are often used in Harrington instrumentation to provide stability and support to the spine. They are typically attached to the pedicle screws and help in correcting spinal deformities. Sublaminar wires are also used in Harrington instrumentation but they are not the correct answer as rods play a more crucial role in providing stability. Interbody grafts are used in spinal fusion surgeries but they are not specific to Harrington instrumentation. Therefore, the correct answer is rods.

Explanation

Rods are often used in Harrington instrumentation to provide stability and support to the spine. They are typically attached to the pedicle screws and help in correcting spinal deformities. Sublaminar wires are also used in Harrington instrumentation but they are not the correct answer as rods play a more crucial role in providing stability. Interbody grafts are used in spinal fusion surgeries but they are not specific to Harrington instrumentation. Therefore, the correct answer is rods.

81. Transection or spinal shock affects function below the level of injury, resulting in loss of:

Motor function

Reflexes

Visceral sensation

All of the above

Transection or spinal shock refers to the temporary loss of spinal cord function below the level of injury. This can result in the loss of motor function, reflexes, and visceral sensation. Motor function refers to the ability to move muscles and control voluntary movements. Reflexes are involuntary responses to stimuli, such as the knee jerk reflex. Visceral sensation refers to the ability to perceive sensations from internal organs, such as pain or pressure. Therefore, all of the options mentioned - motor function, reflexes, and visceral sensation - are affected by transection or spinal shock.

Explanation

Transection or spinal shock refers to the temporary loss of spinal cord function below the level of injury. This can result in the loss of motor function, reflexes, and visceral sensation. Motor function refers to the ability to move muscles and control voluntary movements. Reflexes are involuntary responses to stimuli, such as the knee jerk reflex. Visceral sensation refers to the ability to perceive sensations from internal organs, such as pain or pressure. Therefore, all of the options mentioned - motor function, reflexes, and visceral sensation - are affected by transection or spinal shock.

82. The best muscles for L4-S1 pedicle screw stimulation would be the:

Vastus medialis and biceps femoris

Abductor halluces and abductor digitorum minimi

Gastroc and Abductor halluces

Tibialis anterior and gastrocnemius

The L4-S1 pedicle screw stimulation is used for spinal fusion surgery in the lower back. The tibialis anterior and gastrocnemius muscles are located in the lower leg and are involved in ankle movement and stability. These muscles are essential for walking, running, and maintaining balance. Stimulating these muscles during the surgery can help improve the overall stability and function of the lower back. Therefore, the tibialis anterior and gastrocnemius muscles would be the best choice for L4-S1 pedicle screw stimulation.

Explanation

The L4-S1 pedicle screw stimulation is used for spinal fusion surgery in the lower back. The tibialis anterior and gastrocnemius muscles are located in the lower leg and are involved in ankle movement and stability. These muscles are essential for walking, running, and maintaining balance. Stimulating these muscles during the surgery can help improve the overall stability and function of the lower back. Therefore, the tibialis anterior and gastrocnemius muscles would be the best choice for L4-S1 pedicle screw stimulation.

83. In the central nervous system, a myelin sheath forms around the

Axon

Gila

Cell body

Dendrites

The myelin sheath is a protective covering that forms around the axon in the central nervous system. It helps to insulate and speed up the transmission of electrical signals along the axon. The myelin sheath is formed by specialized cells called oligodendrocytes in the central nervous system. It is not formed around the gila, cell body, or dendrites.

Explanation

The myelin sheath is a protective covering that forms around the axon in the central nervous system. It helps to insulate and speed up the transmission of electrical signals along the axon. The myelin sheath is formed by specialized cells called oligodendrocytes in the central nervous system. It is not formed around the gila, cell body, or dendrites.

84. In the central nervous system a myelin sheath forms around the:

Axon

Glia

Cell body

Dendrites

The myelin sheath forms around the axon in the central nervous system. The myelin sheath is a protective covering made up of fatty substances that insulates the axon and helps to increase the speed of nerve impulse transmission. The axon is responsible for transmitting electrical signals from the cell body of a neuron to other neurons or target cells.

Explanation

The myelin sheath forms around the axon in the central nervous system. The myelin sheath is a protective covering made up of fatty substances that insulates the axon and helps to increase the speed of nerve impulse transmission. The axon is responsible for transmitting electrical signals from the cell body of a neuron to other neurons or target cells.

85. The primary auditory receptive area for the cortex is the:

Pre-central gyrus

Anterior temporal transverse gyrus

Post-central gyrus

Medulla

The anterior temporal transverse gyrus is the primary auditory receptive area in the cortex. This region is responsible for processing and interpreting auditory information received from the ears. It plays a crucial role in the perception of sound, including recognizing and understanding speech, music, and other auditory stimuli. The other options, such as the pre-central gyrus, post-central gyrus, and medulla, are not directly involved in auditory processing and have different functions in the brain.

Explanation

The anterior temporal transverse gyrus is the primary auditory receptive area in the cortex. This region is responsible for processing and interpreting auditory information received from the ears. It plays a crucial role in the perception of sound, including recognizing and understanding speech, music, and other auditory stimuli. The other options, such as the pre-central gyrus, post-central gyrus, and medulla, are not directly involved in auditory processing and have different functions in the brain.

86. What is the major descending motor tract?

Dorsal column pathway

Spinothalamic tract

Corticospinal tract

Homunculus

The major descending motor tract is the corticospinal tract. This tract is responsible for carrying motor signals from the cerebral cortex to the spinal cord, which then controls voluntary movements of the body. It is the largest and most important motor pathway in humans, playing a crucial role in fine motor control and skilled movements.

Explanation

The major descending motor tract is the corticospinal tract. This tract is responsible for carrying motor signals from the cerebral cortex to the spinal cord, which then controls voluntary movements of the body. It is the largest and most important motor pathway in humans, playing a crucial role in fine motor control and skilled movements.

87. With tibial nerve stimulation, decreased NCV between the popliteal fossa and L3 potential, with normal NCV to popliteal fossa indicates:

Potential lesion between popliteal fossa and cauda equina

Potential lesion between the ankle and popliteal fossa

The extremity should be cooled and the study repeated

A normal pathway

Tibial nerve stimulation is used to assess the conduction of nerve impulses along the tibial nerve pathway. In this scenario, a decreased NCV (nerve conduction velocity) between the popliteal fossa (area behind the knee) and L3 potential, with normal NCV to the popliteal fossa, suggests a potential lesion between the popliteal fossa and the cauda equina (the bundle of nerves at the base of the spine). This indicates that there may be a problem with nerve conduction in the lower back region, specifically along the pathway from the popliteal fossa to the cauda equina.

Explanation

Tibial nerve stimulation is used to assess the conduction of nerve impulses along the tibial nerve pathway. In this scenario, a decreased NCV (nerve conduction velocity) between the popliteal fossa (area behind the knee) and L3 potential, with normal NCV to the popliteal fossa, suggests a potential lesion between the popliteal fossa and the cauda equina (the bundle of nerves at the base of the spine). This indicates that there may be a problem with nerve conduction in the lower back region, specifically along the pathway from the popliteal fossa to the cauda equina.

88. In BAEP's excessive earwax (cerumen) causes:

Increase in absolute latency, normal inter-peak latencies

Increased I-III, Increased I-V inter-peak

Normal BAEP

Increased III - V, Increased I-V

Excessive earwax (cerumen) can cause an increase in absolute latency, which refers to the time it takes for the auditory signal to travel from the ear to the brainstem. This increase in latency can be due to the obstruction or blockage caused by the excess earwax. However, the inter-peak latencies, which measure the time between different peaks in the BAEP waveform, remain normal. This suggests that the neural conduction within the brainstem is not affected by the excess earwax. Therefore, the correct answer is that excessive earwax causes an increase in absolute latency but normal inter-peak latencies.

Explanation

Excessive earwax (cerumen) can cause an increase in absolute latency, which refers to the time it takes for the auditory signal to travel from the ear to the brainstem. This increase in latency can be due to the obstruction or blockage caused by the excess earwax. However, the inter-peak latencies, which measure the time between different peaks in the BAEP waveform, remain normal. This suggests that the neural conduction within the brainstem is not affected by the excess earwax. Therefore, the correct answer is that excessive earwax causes an increase in absolute latency but normal inter-peak latencies.

89. ABR condensation clicks from the transducer can cause

Movement of the tympanic membrane toward the cochlea

Movement of the tympanic membrane away from the cochlea

Movement toward and away from the cochlea

No movement at the cochlea

ABR condensation clicks from the transducer can cause movement of the tympanic membrane toward the cochlea. ABR stands for Auditory Brainstem Response, which is a test used to evaluate the auditory pathway. Condensation clicks are brief, high-intensity sounds that are used in the ABR test. When these clicks are presented, they cause a displacement of the tympanic membrane, which is the thin membrane that separates the outer ear from the middle ear. In this case, the movement is toward the cochlea, which is the part of the inner ear responsible for hearing.

Explanation

ABR condensation clicks from the transducer can cause movement of the tympanic membrane toward the cochlea. ABR stands for Auditory Brainstem Response, which is a test used to evaluate the auditory pathway. Condensation clicks are brief, high-intensity sounds that are used in the ABR test. When these clicks are presented, they cause a displacement of the tympanic membrane, which is the thin membrane that separates the outer ear from the middle ear. In this case, the movement is toward the cochlea, which is the part of the inner ear responsible for hearing.

90. Selective dorsal rhizotomy:

Reduces spasticity

Increases spasticity

Validates hypothermia

Causes ataxia

Selective dorsal rhizotomy is a surgical procedure that involves cutting specific nerve fibers in the spinal cord to reduce spasticity. Spasticity is a condition characterized by involuntary muscle stiffness and contractions, which can lead to difficulties in movement and coordination. By selectively cutting the nerve fibers responsible for these abnormal muscle contractions, the procedure aims to reduce spasticity and improve overall motor function. Therefore, the correct answer is "Reduces spasticity."

Explanation

Selective dorsal rhizotomy is a surgical procedure that involves cutting specific nerve fibers in the spinal cord to reduce spasticity. Spasticity is a condition characterized by involuntary muscle stiffness and contractions, which can lead to difficulties in movement and coordination. By selectively cutting the nerve fibers responsible for these abnormal muscle contractions, the procedure aims to reduce spasticity and improve overall motor function. Therefore, the correct answer is "Reduces spasticity."

91. The ISOLA type of spinal instrumentation involves

A combination of hook and screw method

Severing the cauda equina

Harrington rods

Placement of grid electrodes

The ISOLA type of spinal instrumentation involves a combination of the hook and screw method. This means that both hooks and screws are used to anchor the spinal instrumentation in place. This combination provides stability and allows for better fixation of the instrumentation to the spine.

Explanation

The ISOLA type of spinal instrumentation involves a combination of the hook and screw method. This means that both hooks and screws are used to anchor the spinal instrumentation in place. This combination provides stability and allows for better fixation of the instrumentation to the spine.

92. Collateral circulation from one hemisphere to the other during cross-clamping a carotid artery in a CEA surgery occurs via:

The anterior cerebral artery.

The middle cerebral artery.

The posterior cerebral artery.

The Circle of Willis.

The vertebral artery.

During cross-clamping of a carotid artery in a carotid endarterectomy (CEA) surgery, collateral circulation from one hemisphere to the other occurs via the Circle of Willis. The Circle of Willis is a circular network of arteries at the base of the brain that connects the carotid and vertebral arteries. It provides an alternative pathway for blood flow in case of a blockage or interruption in one of the arteries supplying the brain. Therefore, when the carotid artery is temporarily clamped during CEA surgery, blood can still flow to the other hemisphere through the collateral vessels in the Circle of Willis.

Explanation

During cross-clamping of a carotid artery in a carotid endarterectomy (CEA) surgery, collateral circulation from one hemisphere to the other occurs via the Circle of Willis. The Circle of Willis is a circular network of arteries at the base of the brain that connects the carotid and vertebral arteries. It provides an alternative pathway for blood flow in case of a blockage or interruption in one of the arteries supplying the brain. Therefore, when the carotid artery is temporarily clamped during CEA surgery, blood can still flow to the other hemisphere through the collateral vessels in the Circle of Willis.

93. Compared to surface electrodes, needle recording electrodes tend to have

Higher impedance

Better high frequency responses

Less risk of transmitting diseases

Less distortion of low frequencies

Needle recording electrodes tend to have higher impedance compared to surface electrodes. Impedance refers to the resistance encountered by an electrical circuit to the flow of current. In the case of needle recording electrodes, the higher impedance is beneficial as it allows for more accurate and precise measurements of electrical signals. Higher impedance helps to minimize signal loss and interference, resulting in clearer and more reliable recordings. Therefore, needle recording electrodes are preferred in situations where high-quality and detailed recordings are required.

Explanation

Needle recording electrodes tend to have higher impedance compared to surface electrodes. Impedance refers to the resistance encountered by an electrical circuit to the flow of current. In the case of needle recording electrodes, the higher impedance is beneficial as it allows for more accurate and precise measurements of electrical signals. Higher impedance helps to minimize signal loss and interference, resulting in clearer and more reliable recordings. Therefore, needle recording electrodes are preferred in situations where high-quality and detailed recordings are required.

94. The recommended amplitude resolution of the analog to digital converter must be a MINIMUM of

2 bits

4 bits

8 bits

16 bits

The recommended amplitude resolution of the analog to digital converter must be a minimum of 8 bits. This is because 8 bits allows for a greater range of values to be represented, providing more accurate and precise measurements of the analog signal. With a higher resolution, the analog to digital converter can capture more detail and nuances in the signal, resulting in a higher fidelity digital representation.

Explanation

The recommended amplitude resolution of the analog to digital converter must be a minimum of 8 bits. This is because 8 bits allows for a greater range of values to be represented, providing more accurate and precise measurements of the analog signal. With a higher resolution, the analog to digital converter can capture more detail and nuances in the signal, resulting in a higher fidelity digital representation.

95. Which of the following is the time from the beginning to the end of each evoked potential sweep?

Rate

Latency

Real Time

Analysis Time

The analysis time refers to the duration from the start to the end of each evoked potential sweep. This is the period during which the data is collected, processed, and analyzed to extract relevant information. It is the time taken to evaluate the recorded signals and extract useful data for further analysis or interpretation.

Explanation

The analysis time refers to the duration from the start to the end of each evoked potential sweep. This is the period during which the data is collected, processed, and analyzed to extract relevant information. It is the time taken to evaluate the recorded signals and extract useful data for further analysis or interpretation.

96. When testing BAEPs you get a wave I on your contralateral ear montage. What do you do?

Increase click intensity

Change polarity of click to condensation

Check ear phones for proper side stimulation

Change polarity of click to rarefaction

In order to determine the cause of the wave I on the contralateral ear montage when testing BAEPs, it is necessary to check the earphones for proper side stimulation. This means ensuring that the earphones are correctly positioned and delivering the stimuli to the intended ear. By checking the earphones, any issues with improper side stimulation can be identified and corrected, leading to more accurate test results.

Explanation

In order to determine the cause of the wave I on the contralateral ear montage when testing BAEPs, it is necessary to check the earphones for proper side stimulation. This means ensuring that the earphones are correctly positioned and delivering the stimuli to the intended ear. By checking the earphones, any issues with improper side stimulation can be identified and corrected, leading to more accurate test results.

97. When monitoring the facial nerve:

Long-lasting muscle relaxants must be avoided

Bipolar electrodes should be placed in the larynx

Needle electrodes should be placed in the masseter

Inhalational anesthetic agents must be avoided

When monitoring the facial nerve, long-lasting muscle relaxants must be avoided because they can interfere with the ability to assess facial muscle movement. The facial nerve controls the muscles of facial expression, so it is important to be able to observe any changes or abnormalities in these muscles during monitoring. Using long-lasting muscle relaxants could potentially mask or inhibit the ability to detect these changes, leading to inaccurate monitoring results. Therefore, it is best to avoid the use of long-lasting muscle relaxants when monitoring the facial nerve.

Explanation

When monitoring the facial nerve, long-lasting muscle relaxants must be avoided because they can interfere with the ability to assess facial muscle movement. The facial nerve controls the muscles of facial expression, so it is important to be able to observe any changes or abnormalities in these muscles during monitoring. Using long-lasting muscle relaxants could potentially mask or inhibit the ability to detect these changes, leading to inaccurate monitoring results. Therefore, it is best to avoid the use of long-lasting muscle relaxants when monitoring the facial nerve.

98. Is the somatosensory system afferent or efferent?

Efferent

Afferent

Neither

Both

the somatosensory system carries information TOWARDS the brain

Explanation

the somatosensory system carries information TOWARDS the brain

99. Dyskinesia:

Abnormal movement

Abnormal sensation

Ringing in ears

Seizures

The term "dyskinesia" refers to abnormal movement. It is a medical condition characterized by involuntary, repetitive, and sometimes unpredictable movements of the muscles. These movements can be jerky, twisting, or writhing in nature. Dyskinesia can affect various parts of the body, including the face, limbs, and trunk. It can be caused by certain medications, neurological disorders, or brain injuries. The other options mentioned in the question, such as abnormal sensation, ringing in ears, and seizures, are not directly related to dyskinesia. Therefore, the correct answer is "Abnormal movement."

Explanation

The term "dyskinesia" refers to abnormal movement. It is a medical condition characterized by involuntary, repetitive, and sometimes unpredictable movements of the muscles. These movements can be jerky, twisting, or writhing in nature. Dyskinesia can affect various parts of the body, including the face, limbs, and trunk. It can be caused by certain medications, neurological disorders, or brain injuries. The other options mentioned in the question, such as abnormal sensation, ringing in ears, and seizures, are not directly related to dyskinesia. Therefore, the correct answer is "Abnormal movement."

100. Which of the following is most likely to lead to vascular compromise?

Pedicle probes

Sublaminar wires

Epidural electrodes

EEG recordings

Sublaminar wires because they pass through to the canal and there is a chance of hitting the posterior spinal arteries

Explanation

Sublaminar wires because they pass through to the canal and there is a chance of hitting the posterior spinal arteries

101. How frequently should SSEP's be performed in the operating room?

Every seven minutes

Continuously except when cautery prohibits collection

Continuously during critical periods, less frequently during non-critical periods

Every ten minutes after warning the surgeon first

SSEP's (Somatosensory Evoked Potentials) should be performed continuously in the operating room except when cautery prohibits collection. Cautery can interfere with the accurate collection of SSEP's, so it is necessary to temporarily pause the monitoring during cautery use. This ensures that the data collected is reliable and not affected by the cautery device.

Explanation

SSEP's (Somatosensory Evoked Potentials) should be performed continuously in the operating room except when cautery prohibits collection. Cautery can interfere with the accurate collection of SSEP's, so it is necessary to temporarily pause the monitoring during cautery use. This ensures that the data collected is reliable and not affected by the cautery device.

102. The troubleshooting method to best determine the source of a nonphysiologic artifact is:

View the raw input

Decrease sensitivity

Decrease the high frequency filter

Increase the low frequency filter

Viewing the raw input is the best troubleshooting method to determine the source of a nonphysiologic artifact. By examining the raw input, one can directly observe any abnormalities or interference that may be causing the artifact. This allows for a more accurate identification of the source and helps in determining the appropriate steps to address the issue. Decreasing sensitivity, decreasing the high frequency filter, and increasing the low frequency filter can also be helpful in reducing artifacts, but viewing the raw input provides the most direct and comprehensive information for troubleshooting.

Explanation

Viewing the raw input is the best troubleshooting method to determine the source of a nonphysiologic artifact. By examining the raw input, one can directly observe any abnormalities or interference that may be causing the artifact. This allows for a more accurate identification of the source and helps in determining the appropriate steps to address the issue. Decreasing sensitivity, decreasing the high frequency filter, and increasing the low frequency filter can also be helpful in reducing artifacts, but viewing the raw input provides the most direct and comprehensive information for troubleshooting.

103. Ankylosis is?

Foot drop

Wrist drop

Fused joint

Arterial Occlusion

Ankylosis refers to the condition where a joint becomes fused or immobile due to the abnormal adhesion of the bones. This means that the joint loses its ability to move freely, causing stiffness and limited range of motion. Therefore, the correct answer for this question is "Fused joint".

Explanation

Ankylosis refers to the condition where a joint becomes fused or immobile due to the abnormal adhesion of the bones. This means that the joint loses its ability to move freely, causing stiffness and limited range of motion. Therefore, the correct answer for this question is "Fused joint".

104. Every lab should have _______ for all chemicals used in the lab such as collodian, acetone, NuPrep, Ten-20 cream, etc.

Standing orders for monthly shipments

MSDS (Medical Safety Data Sheets)

Zip Lock Bags

Red hazard waste trash containers with lids

Every lab should have MSDS (Medical Safety Data Sheets) for all chemicals used in the lab such as collodian, acetone, NuPrep, Ten-20 cream, etc. MSDS provides important information about the hazards, handling, storage, and disposal of chemicals. It helps lab personnel to understand the potential risks associated with the chemicals and take necessary precautions to ensure their safety. Having MSDS readily available ensures that lab workers have access to the necessary information to handle chemicals safely and respond appropriately in case of emergencies.

Explanation

Every lab should have MSDS (Medical Safety Data Sheets) for all chemicals used in the lab such as collodian, acetone, NuPrep, Ten-20 cream, etc. MSDS provides important information about the hazards, handling, storage, and disposal of chemicals. It helps lab personnel to understand the potential risks associated with the chemicals and take necessary precautions to ensure their safety. Having MSDS readily available ensures that lab workers have access to the necessary information to handle chemicals safely and respond appropriately in case of emergencies.

105. Afferent pathways

Conduct impulses from the periphery toward the CNS

Conduct impulses from the CNS toward the PNS

Are motor responses

Are VEP responses

Afferent: conducting or conducted inward or toward something (for nerves, the central nervous system; for blood vessels, the organ supplied). Afferent- Arrive brain

Efferent: conducted or conducting outward or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied). Efferent-Exit brain

Explanation

Afferent: conducting or conducted inward or toward something (for nerves, the central nervous system; for blood vessels, the organ supplied). Afferent- Arrive brain

Efferent: conducted or conducting outward or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied). Efferent-Exit brain

106. Spinal nerve roots arise from the sides of the spinal cord and emerge from:

The Subarachnoid Space

The Lamina

The intervertebral foramina

The pedicle

The intervertebral foramina is the correct answer because spinal nerve roots emerge from these openings between adjacent vertebrae. These foramina provide a pathway for the nerves to exit the spinal column and connect with the rest of the body. The other options, such as the subarachnoid space, lamina, and pedicle, are not the specific locations where spinal nerve roots emerge.

Explanation

The intervertebral foramina is the correct answer because spinal nerve roots emerge from these openings between adjacent vertebrae. These foramina provide a pathway for the nerves to exit the spinal column and connect with the rest of the body. The other options, such as the subarachnoid space, lamina, and pedicle, are not the specific locations where spinal nerve roots emerge.

107. In ABR stimulation, the stimulus type which causes a negative pressure resulting in a slightly earlier latency is

Alternating

Condensation

Triggered

Rarefaction

In ABR stimulation, rarefaction is the stimulus type that causes a negative pressure resulting in a slightly earlier latency. Rarefaction refers to the reduction in air pressure during sound waves, causing a decrease in density and an expansion of the medium. This change in pressure can lead to a slightly earlier response in the auditory brainstem, affecting the latency of the response.

Explanation

In ABR stimulation, rarefaction is the stimulus type that causes a negative pressure resulting in a slightly earlier latency. Rarefaction refers to the reduction in air pressure during sound waves, causing a decrease in density and an expansion of the medium. This change in pressure can lead to a slightly earlier response in the auditory brainstem, affecting the latency of the response.

108. What cranial nerves monitoring will be ideal for CPA tumor removal procedure?

V and VII

VII and VIII

VIII and IX

VII, VIII, and XII

During a CPA tumor removal procedure, monitoring cranial nerves VII (facial nerve) and VIII (vestibulocochlear nerve) would be ideal. The facial nerve controls the movement of the facial muscles, while the vestibulocochlear nerve is responsible for hearing and balance. Monitoring these nerves allows the surgeon to ensure their integrity and avoid any damage during the procedure.

Explanation

During a CPA tumor removal procedure, monitoring cranial nerves VII (facial nerve) and VIII (vestibulocochlear nerve) would be ideal. The facial nerve controls the movement of the facial muscles, while the vestibulocochlear nerve is responsible for hearing and balance. Monitoring these nerves allows the surgeon to ensure their integrity and avoid any damage during the procedure.

109. What is the typical MINIMUM common mode rejction ratio of in-phase signals recommended for evoked potential instruments?

1,000:1

5,000:1

10,000:1

2:1

The typical MINIMUM common mode rejection ratio of in-phase signals recommended for evoked potential instruments is 10,000:1. This means that the instrument is able to reject common mode signals (signals that are present in both the desired signal and the noise) by a ratio of 10,000 to 1. A high common mode rejection ratio is important in evoked potential instruments to ensure that the desired signals are accurately measured and any unwanted noise or interference is minimized.

Explanation

The typical MINIMUM common mode rejection ratio of in-phase signals recommended for evoked potential instruments is 10,000:1. This means that the instrument is able to reject common mode signals (signals that are present in both the desired signal and the noise) by a ratio of 10,000 to 1. A high common mode rejection ratio is important in evoked potential instruments to ensure that the desired signals are accurately measured and any unwanted noise or interference is minimized.

110. Which is a cochlear microphonic potential?

Integrated acuity of many nerve fibers

Potential from the cochlear hair cells

Potential in the cochlea nucleus

Acuity from the VIII nerve fibers

The cochlear microphonic potential refers to the electrical potential generated by the hair cells in the cochlea. These hair cells are responsible for converting sound vibrations into electrical signals that can be interpreted by the brain. Therefore, the potential from the cochlear hair cells is the correct answer as it accurately describes the source of the cochlear microphonic potential.

Explanation

The cochlear microphonic potential refers to the electrical potential generated by the hair cells in the cochlea. These hair cells are responsible for converting sound vibrations into electrical signals that can be interpreted by the brain. Therefore, the potential from the cochlear hair cells is the correct answer as it accurately describes the source of the cochlear microphonic potential.

111. Syringomyelia (Syrinx) is:

Forward movement of the body of a lumbar vertebra

A bony protrusion called a bone spur

Neurofibromatosis

Deterioration of the spinal cord gray matter which is replaced by a large cyst

Syringomyelia, also known as Syrinx, is a condition characterized by the deterioration of the gray matter in the spinal cord. This deterioration leads to the formation of a large cyst within the spinal cord. The cyst can expand over time, causing damage and compression of the surrounding nerve tissue. Symptoms of Syringomyelia can include pain, weakness, sensory loss, and problems with coordination. Treatment options for Syringomyelia may include surgery to drain the cyst and relieve pressure on the spinal cord.

Explanation

Syringomyelia, also known as Syrinx, is a condition characterized by the deterioration of the gray matter in the spinal cord. This deterioration leads to the formation of a large cyst within the spinal cord. The cyst can expand over time, causing damage and compression of the surrounding nerve tissue. Symptoms of Syringomyelia can include pain, weakness, sensory loss, and problems with coordination. Treatment options for Syringomyelia may include surgery to drain the cyst and relieve pressure on the spinal cord.

112. When monitoring Brainstem auditory evoked potentials intraoperatively it is recommended to warn the surgeon when an increase of the following occurs?

The latency of wave V is less than 1.0 millisecond

The latency of wave I is 1 millisecond

The latency of wave V is 1.0 or greater

The interpeak latency of waves I-V is 1.0 or less

When monitoring Brainstem auditory evoked potentials intraoperatively, it is recommended to warn the surgeon when the latency of wave V is 1.0 or greater. This is because an increase in the latency of wave V indicates a delay in the transmission of auditory signals from the brainstem to the auditory cortex. This delay could be a sign of nerve damage or dysfunction and may require immediate attention from the surgeon to prevent further complications.

Explanation

When monitoring Brainstem auditory evoked potentials intraoperatively, it is recommended to warn the surgeon when the latency of wave V is 1.0 or greater. This is because an increase in the latency of wave V indicates a delay in the transmission of auditory signals from the brainstem to the auditory cortex. This delay could be a sign of nerve damage or dysfunction and may require immediate attention from the surgeon to prevent further complications.

113. Afferent Nerves

Conduct impules away from the central nervous system

Control ability to speak

Control emotional responses

Conduct impulses toward the central nervous system

Afferent nerves conduct impulses toward the central nervous system. This means that they transmit sensory information from the body's sensory receptors to the brain and spinal cord. This allows the brain to receive information about the external environment and the internal state of the body. Afferent nerves are responsible for sensations such as touch, pain, temperature, and proprioception. They play a crucial role in allowing the body to respond to stimuli and maintain homeostasis.

Explanation

Afferent nerves conduct impulses toward the central nervous system. This means that they transmit sensory information from the body's sensory receptors to the brain and spinal cord. This allows the brain to receive information about the external environment and the internal state of the body. Afferent nerves are responsible for sensations such as touch, pain, temperature, and proprioception. They play a crucial role in allowing the body to respond to stimuli and maintain homeostasis.

114. What drug will most likely affect SSEPs?

Remifentanyl

Rocuronium

Morphine

Sevoflurane

Sevoflurane is a volatile anesthetic that is commonly used during surgery. It is known to suppress the amplitude and increase the latency of somatosensory evoked potentials (SSEPs), which are electrical signals generated in response to sensory stimulation. This means that sevoflurane is likely to have an effect on SSEPs, potentially impairing the ability to monitor the integrity of the nervous system during surgery. Remifentanyl, rocuronium, and morphine are not known to have a significant effect on SSEPs.

Explanation

Sevoflurane is a volatile anesthetic that is commonly used during surgery. It is known to suppress the amplitude and increase the latency of somatosensory evoked potentials (SSEPs), which are electrical signals generated in response to sensory stimulation. This means that sevoflurane is likely to have an effect on SSEPs, potentially impairing the ability to monitor the integrity of the nervous system during surgery. Remifentanyl, rocuronium, and morphine are not known to have a significant effect on SSEPs.

115. Which surgical approach will sacrifice hearing?

Middle fossa

Retromastoid

Translabyrinthine

Suboccipital

The translabyrinthine surgical approach involves removing the entire labyrinth, which includes the cochlea, vestibule, and semicircular canals. This approach is commonly used for the removal of acoustic neuromas, but it sacrifices hearing in the affected ear because it involves cutting the auditory nerve. Therefore, the translabyrinthine approach is the correct answer as it is the only surgical approach that will sacrifice hearing.

Explanation

The translabyrinthine surgical approach involves removing the entire labyrinth, which includes the cochlea, vestibule, and semicircular canals. This approach is commonly used for the removal of acoustic neuromas, but it sacrifices hearing in the affected ear because it involves cutting the auditory nerve. Therefore, the translabyrinthine approach is the correct answer as it is the only surgical approach that will sacrifice hearing.

116. What is the maximum allowable chassis current leakage of an evoked potential system?

100uamperes

200uamperes

300uamperes

500uamperes

The maximum allowable chassis current leakage of an evoked potential system is 100uamperes. This means that the system should not have a current leakage exceeding 100uamperes in order to operate within the acceptable limits.

Explanation

The maximum allowable chassis current leakage of an evoked potential system is 100uamperes. This means that the system should not have a current leakage exceeding 100uamperes in order to operate within the acceptable limits.

117. A shocking sensation that occurs throughout the body during neck flexion is called:

Tinel's Sign

L'Hermittes sign

Vascular disease

Guillaime-Barre syndrome

L'Hermittes sign is a shocking sensation that occurs throughout the body during neck flexion. It is commonly associated with conditions such as multiple sclerosis or cervical spine injury. This sensation is often described as an electric shock or tingling that radiates down the spine and into the limbs. It can be triggered by simple movements such as bending the neck forward. L'Hermittes sign is a neurological symptom and is not related to vascular disease or Guillaime-Barre syndrome.

Explanation

L'Hermittes sign is a shocking sensation that occurs throughout the body during neck flexion. It is commonly associated with conditions such as multiple sclerosis or cervical spine injury. This sensation is often described as an electric shock or tingling that radiates down the spine and into the limbs. It can be triggered by simple movements such as bending the neck forward. L'Hermittes sign is a neurological symptom and is not related to vascular disease or Guillaime-Barre syndrome.

118. Hypothermia

Has no effect on evoked potential latencies

Decreases evoked potential latency

Increases evoked potential latency

A variable effect on evoked potential latency

Hypothermia decreases peripheral conduction velocity…. So therefore it increases the latency of evoked potentials.

Explanation

Hypothermia decreases peripheral conduction velocity…. So therefore it increases the latency of evoked potentials.

119. Primary monitoring modaility if the surgery were at C1-C5?

Median

Ulnar

Posterior tibial

CN VIII

The primary monitoring modality for surgery at C1-C5 is the Median nerve. The Median nerve is responsible for innervating the muscles in the forearm, hand, and fingers. Monitoring this nerve during surgery helps to ensure the integrity of its function and allows for early detection of any potential nerve damage or injury. This is especially important in surgeries involving the cervical spine, as any damage to the Median nerve can result in significant loss of hand and finger function. Therefore, monitoring the Median nerve is crucial in maintaining the patient's neurological status during C1-C5 surgery.

Explanation

The primary monitoring modality for surgery at C1-C5 is the Median nerve. The Median nerve is responsible for innervating the muscles in the forearm, hand, and fingers. Monitoring this nerve during surgery helps to ensure the integrity of its function and allows for early detection of any potential nerve damage or injury. This is especially important in surgeries involving the cervical spine, as any damage to the Median nerve can result in significant loss of hand and finger function. Therefore, monitoring the Median nerve is crucial in maintaining the patient's neurological status during C1-C5 surgery.

120. A positive Babinski reflex could indicate:

A fractured eardrum

A regeneration of damaged nerve fibers

A normal finding in an adult

Severe spinal cord trauma

A positive Babinski reflex is characterized by the extension of the big toe and fanning out of the other toes when the sole of the foot is stimulated. This reflex is normally present in infants but should disappear as the nervous system matures. In adults, a positive Babinski reflex is usually an abnormal finding and can indicate severe spinal cord trauma. In such cases, the reflex is a sign of upper motor neuron dysfunction, suggesting damage to the spinal cord.

Explanation

A positive Babinski reflex is characterized by the extension of the big toe and fanning out of the other toes when the sole of the foot is stimulated. This reflex is normally present in infants but should disappear as the nervous system matures. In adults, a positive Babinski reflex is usually an abnormal finding and can indicate severe spinal cord trauma. In such cases, the reflex is a sign of upper motor neuron dysfunction, suggesting damage to the spinal cord.

121. Which of the following is a reason why a false-negative could occur?

The lesion occurs in a structure not involved in the pathway being monitored

Significant changes were not noted or communicated

The documentation was incomplete

The surgical procedure was revised due to data changes

False negatives are more dangerous than false positives, because they miss the detection of a problem, either because the structures being compromised were not actually monitored, or because the monitoring was incorrect or misinterpreted

False Negative: no data change and patient wakes up with a deficit
False Positive: change in data and patient has no deficits upon wake up

Explanation

False negatives are more dangerous than false positives, because they miss the detection of a problem, either because the structures being compromised were not actually monitored, or because the monitoring was incorrect or misinterpreted

False Negative: no data change and patient wakes up with a deficit
False Positive: change in data and patient has no deficits upon wake up

122. Which of the following waves in the BAEP is a near-field potential?

I

II

III

IV

V

In BAEP (Brainstem Auditory Evoked Potential), a near-field potential refers to the electrical activity that is generated close to the recording electrode. Among the given options, Wave I is considered a near-field potential because it represents the electrical activity generated by the auditory nerve close to the cochlea. Waves II, III, IV, and V represent activity from more distant structures in the auditory pathway.

Explanation

In BAEP (Brainstem Auditory Evoked Potential), a near-field potential refers to the electrical activity that is generated close to the recording electrode. Among the given options, Wave I is considered a near-field potential because it represents the electrical activity generated by the auditory nerve close to the cochlea. Waves II, III, IV, and V represent activity from more distant structures in the auditory pathway.

123. Brown-Sequard syndrome:

Degeneration of cortical neurons

Myopathy

Vascular disease

Hemi-spinal cord lesion

The correct answer is "Hemi-spinal cord lesion". Brown-Sequard syndrome is a neurological condition caused by damage to one half of the spinal cord. This results in a loss of motor function and proprioception on the same side as the lesion, as well as loss of pain and temperature sensation on the opposite side. Therefore, a hemi-spinal cord lesion is the most appropriate explanation for Brown-Sequard syndrome.

Explanation

The correct answer is "Hemi-spinal cord lesion". Brown-Sequard syndrome is a neurological condition caused by damage to one half of the spinal cord. This results in a loss of motor function and proprioception on the same side as the lesion, as well as loss of pain and temperature sensation on the opposite side. Therefore, a hemi-spinal cord lesion is the most appropriate explanation for Brown-Sequard syndrome.

124. Delayed absolute latencies of brainstem auditory evoked potentials which mimic a conductive hearing loss are most likely caused by

Rhinitis

Gingivitis

Otitis

Conjunctivitis

Delayed absolute latencies of brainstem auditory evoked potentials which mimic a conductive hearing loss are most likely caused by otitis. Otitis refers to inflammation or infection of the ear, which can affect the transmission of sound waves to the brainstem. This can result in delayed latencies of the brainstem auditory evoked potentials, leading to a similar pattern as seen in conductive hearing loss. Rhinitis, gingivitis, and conjunctivitis are not directly related to the auditory system and would not typically cause delayed latencies in brainstem auditory evoked potentials.

Explanation

Delayed absolute latencies of brainstem auditory evoked potentials which mimic a conductive hearing loss are most likely caused by otitis. Otitis refers to inflammation or infection of the ear, which can affect the transmission of sound waves to the brainstem. This can result in delayed latencies of the brainstem auditory evoked potentials, leading to a similar pattern as seen in conductive hearing loss. Rhinitis, gingivitis, and conjunctivitis are not directly related to the auditory system and would not typically cause delayed latencies in brainstem auditory evoked potentials.

125. RADICULOPATHY

Meninges

Spinal Cord

Nerve Roots

Peripheral nerves

The term "radiculopathy" refers to a condition that affects the nerve roots. Radiculopathy occurs when there is compression, irritation, or inflammation of the nerve roots that exit the spinal cord. This can result in pain, numbness, tingling, or weakness along the pathway of the affected nerve. The other options listed, such as meninges, spinal cord, and peripheral nerves, are not specifically associated with radiculopathy.

Explanation

The term "radiculopathy" refers to a condition that affects the nerve roots. Radiculopathy occurs when there is compression, irritation, or inflammation of the nerve roots that exit the spinal cord. This can result in pain, numbness, tingling, or weakness along the pathway of the affected nerve. The other options listed, such as meninges, spinal cord, and peripheral nerves, are not specifically associated with radiculopathy.

126. During posterior fossa approach for removal of an acoustic neuroma, an increase in the latency of wave V is most likely caused by

Fluid in the ear canal

Retraction of the cerebellum

Failure to stimulate

A loss of blood supply to the cochlea

During posterior fossa approach for removal of an acoustic neuroma, an increase in the latency of wave V is most likely caused by retraction of the cerebellum. The acoustic neuroma is located near the cerebellopontine angle, and during the surgical procedure, the cerebellum is retracted to access the tumor. This retraction can put pressure on the auditory nerve, leading to a delay in the conduction of the sound stimulus and thus an increase in the latency of wave V, which represents the auditory nerve response.

Explanation

During posterior fossa approach for removal of an acoustic neuroma, an increase in the latency of wave V is most likely caused by retraction of the cerebellum. The acoustic neuroma is located near the cerebellopontine angle, and during the surgical procedure, the cerebellum is retracted to access the tumor. This retraction can put pressure on the auditory nerve, leading to a delay in the conduction of the sound stimulus and thus an increase in the latency of wave V, which represents the auditory nerve response.

127. The blood supply of the obligate peak of N20 is:

ACA

MCA

Carotid

PSA

The correct answer is MCA because the middle cerebral artery (MCA) is responsible for supplying blood to the lateral surface of the brain, including the areas associated with language, motor function, and sensory perception. The MCA is a major branch of the internal carotid artery and plays a crucial role in maintaining blood flow to the brain. Therefore, it is the most likely blood supply for the obligate peak of N20.

Explanation

The correct answer is MCA because the middle cerebral artery (MCA) is responsible for supplying blood to the lateral surface of the brain, including the areas associated with language, motor function, and sensory perception. The MCA is a major branch of the internal carotid artery and plays a crucial role in maintaining blood flow to the brain. Therefore, it is the most likely blood supply for the obligate peak of N20.

128. When performing asynchronous stimulation for intraoperative SSEPs:

It is difficult to differentiate between left and right side responses

It is easy to differentiate between left and right side responses

There is no difference between left and right responses

Notify the surgeon

When performing asynchronous stimulation for intraoperative SSEPs, it is easy to differentiate between left and right side responses. This means that the responses from the left and right sides can be clearly distinguished and identified. This is important in surgical procedures as it helps the surgeon accurately locate and assess the functioning of specific nerves or areas on either side of the body.

Explanation

When performing asynchronous stimulation for intraoperative SSEPs, it is easy to differentiate between left and right side responses. This means that the responses from the left and right sides can be clearly distinguished and identified. This is important in surgical procedures as it helps the surgeon accurately locate and assess the functioning of specific nerves or areas on either side of the body.

129. Which of the following conditions would most likely alter tibial nerve SSEP responses?

Diabetes

Hypertension

Ataxia

Monday mornings

Diabetes is most likely to alter tibial nerve SSEP responses. Diabetes can lead to nerve damage, known as diabetic neuropathy, which can affect the nerves in the legs and feet, including the tibial nerve. This can result in abnormal sensory nerve signals, which would be reflected in altered SSEP responses. Hypertension, ataxia, and Monday mornings do not typically directly affect the tibial nerve or SSEP responses.

Explanation

Diabetes is most likely to alter tibial nerve SSEP responses. Diabetes can lead to nerve damage, known as diabetic neuropathy, which can affect the nerves in the legs and feet, including the tibial nerve. This can result in abnormal sensory nerve signals, which would be reflected in altered SSEP responses. Hypertension, ataxia, and Monday mornings do not typically directly affect the tibial nerve or SSEP responses.

130. Where are the posterior tibial surface electrodes placed on the leg?

Heel

Inferior and posterior to medial malleolus

Lateral to ankle

Medial to ankle

The posterior tibial surface electrodes are placed inferior and posterior to the medial malleolus. The medial malleolus is the bony prominence on the inner side of the ankle. Placing the electrodes in this location allows for accurate measurement of the electrical activity in the posterior tibial muscle, which is important in diagnosing and monitoring conditions such as peripheral neuropathy and nerve damage.

Explanation

The posterior tibial surface electrodes are placed inferior and posterior to the medial malleolus. The medial malleolus is the bony prominence on the inner side of the ankle. Placing the electrodes in this location allows for accurate measurement of the electrical activity in the posterior tibial muscle, which is important in diagnosing and monitoring conditions such as peripheral neuropathy and nerve damage.

131. Which of the following nerve usually does NOT produce spontaneous EMG activity during intraoperative monitoring?

Heat

Pressure

Ischemia

Irrigation

Ischemia usually does not produce spontaneous EMG activity during intraoperative monitoring. Ischemia refers to a lack of blood supply to a tissue or organ, which can result in a decrease in oxygen and nutrient delivery. This lack of blood supply can lead to cell damage and dysfunction, including the nerves. As a result, ischemic nerves typically do not generate spontaneous EMG activity.

Explanation

Ischemia usually does not produce spontaneous EMG activity during intraoperative monitoring. Ischemia refers to a lack of blood supply to a tissue or organ, which can result in a decrease in oxygen and nutrient delivery. This lack of blood supply can lead to cell damage and dysfunction, including the nerves. As a result, ischemic nerves typically do not generate spontaneous EMG activity.

132. In BAEP's, kinked earphone tubing causes:

Increase in absolute latency, normal inter-peak latencies

Increased I-III increased I-V interpeak

Normal BAEP

Increased III- V, Increased I-V

Kinked earphone tubing can cause an increase in absolute latency, which refers to the time it takes for the brainstem to process the sound stimulus. However, it does not affect the inter-peak latencies, which are the time intervals between different peaks in the BAEP waveform. Therefore, even though there may be a delay in the overall processing of the sound, the relative timing between different peaks remains normal.

Explanation

Kinked earphone tubing can cause an increase in absolute latency, which refers to the time it takes for the brainstem to process the sound stimulus. However, it does not affect the inter-peak latencies, which are the time intervals between different peaks in the BAEP waveform. Therefore, even though there may be a delay in the overall processing of the sound, the relative timing between different peaks remains normal.

133. In BAEP's blood, betadine or irrigation fluid in tubing causes:

Increase in absolute latency, normal inter-peak latencies

Increased I-III, increased I-V inter-peak

Normal BAEP

Increased III-V, increased I-V

When betadine or irrigation fluid is present in the tubing during a BAEP (Brainstem Auditory Evoked Potential) test, it can cause an increase in absolute latency. This means that the time it takes for the auditory signal to travel from the ear to the brainstem is prolonged. However, the inter-peak latencies, which represent the time intervals between different peaks in the BAEP waveform, remain normal. This suggests that the overall waveform shape and timing are not significantly affected by the presence of betadine or irrigation fluid in the tubing.

Explanation

When betadine or irrigation fluid is present in the tubing during a BAEP (Brainstem Auditory Evoked Potential) test, it can cause an increase in absolute latency. This means that the time it takes for the auditory signal to travel from the ear to the brainstem is prolonged. However, the inter-peak latencies, which represent the time intervals between different peaks in the BAEP waveform, remain normal. This suggests that the overall waveform shape and timing are not significantly affected by the presence of betadine or irrigation fluid in the tubing.

134. Broca's area controls:

Receptive speech

Expressive speech

The tongue

Sensation to the mouth

Broca's area is a region in the brain that plays a crucial role in the production of speech. It is responsible for coordinating the muscles involved in speech production, such as the muscles of the tongue, lips, and vocal cords. Damage to Broca's area can result in expressive aphasia, where individuals have difficulty speaking fluently and forming coherent sentences. Therefore, the correct answer is expressive speech.

Explanation

Broca's area is a region in the brain that plays a crucial role in the production of speech. It is responsible for coordinating the muscles involved in speech production, such as the muscles of the tongue, lips, and vocal cords. Damage to Broca's area can result in expressive aphasia, where individuals have difficulty speaking fluently and forming coherent sentences. Therefore, the correct answer is expressive speech.

135. Watershed area in the spinal cord appears at which level?

Cervical

Lumbar

Thoracic

Sacral

The watershed area in the spinal cord appears at the thoracic level. This refers to the region where the arterial blood supply to the spinal cord is particularly vulnerable to ischemia or lack of blood flow. The thoracic level is the middle region of the spinal cord, and it is where the watershed area is most commonly observed.

Explanation

The watershed area in the spinal cord appears at the thoracic level. This refers to the region where the arterial blood supply to the spinal cord is particularly vulnerable to ischemia or lack of blood flow. The thoracic level is the middle region of the spinal cord, and it is where the watershed area is most commonly observed.

136. Ipsilateral hemiplegia and contralateral pain and temperature sensation deficits are indicative of

Degenerative disc disease

Central cord syndrome

Anterior spinal cord syndrome

Brown Sequard syndrome

Ipsilateral hemiplegia and contralateral pain and temperature sensation deficits are characteristic of Brown Sequard syndrome. This syndrome is caused by damage to one half of the spinal cord, resulting in paralysis on the same side as the injury and loss of pain and temperature sensation on the opposite side. Degenerative disc disease, central cord syndrome, and anterior spinal cord syndrome do not typically present with these specific symptoms.

Explanation

Ipsilateral hemiplegia and contralateral pain and temperature sensation deficits are characteristic of Brown Sequard syndrome. This syndrome is caused by damage to one half of the spinal cord, resulting in paralysis on the same side as the injury and loss of pain and temperature sensation on the opposite side. Degenerative disc disease, central cord syndrome, and anterior spinal cord syndrome do not typically present with these specific symptoms.

137. The innermost membrane of connective tissue covering the brain is:

Pia matter

Arachnoid Matter

Dura

Cortex

The pia matter is the innermost membrane of connective tissue covering the brain. It is a delicate and highly vascular layer that closely adheres to the surface of the brain and spinal cord. It provides support and protection to the underlying neural tissue. The arachnoid matter and dura are also layers of connective tissue covering the brain, but they are not the innermost layer. The cortex, on the other hand, refers to the outer layer of the brain responsible for higher cognitive functions and is not a membrane of connective tissue covering the brain.

Explanation

The pia matter is the innermost membrane of connective tissue covering the brain. It is a delicate and highly vascular layer that closely adheres to the surface of the brain and spinal cord. It provides support and protection to the underlying neural tissue. The arachnoid matter and dura are also layers of connective tissue covering the brain, but they are not the innermost layer. The cortex, on the other hand, refers to the outer layer of the brain responsible for higher cognitive functions and is not a membrane of connective tissue covering the brain.

138. Which of the following would most likely be normal in the pre-operative baseline upper extremity SSEP of a patient with a lesion in the dorsal column

N20

P22

Erb's point potential

Central conduction time

In a patient with a lesion in the dorsal column, the most likely normal finding in the pre-operative baseline upper extremity SSEP would be Erb's point potential. SSEP stands for somatosensory evoked potentials, which are electrical responses generated by the nervous system in response to sensory stimuli. Erb's point potential refers to the SSEP waveform generated at the level of the brachial plexus, which is a network of nerves that innervates the upper extremity. Since the lesion is in the dorsal column, which is responsible for transmitting sensory information, it is expected that the SSEP waveform generated at Erb's point would be normal.

Explanation

In a patient with a lesion in the dorsal column, the most likely normal finding in the pre-operative baseline upper extremity SSEP would be Erb's point potential. SSEP stands for somatosensory evoked potentials, which are electrical responses generated by the nervous system in response to sensory stimuli. Erb's point potential refers to the SSEP waveform generated at the level of the brachial plexus, which is a network of nerves that innervates the upper extremity. Since the lesion is in the dorsal column, which is responsible for transmitting sensory information, it is expected that the SSEP waveform generated at Erb's point would be normal.

139. The N13 of the median nerve somatosensory evoked potential is generated in the

Brachial plexus

Medial lemniscus

Cervical spinal cord

Primary somatosensory cortex

The N13 of the median nerve somatosensory evoked potential is generated in the cervical spinal cord. This is because the N13 component represents the electrical activity generated in the spinal cord when the median nerve is stimulated. The brachial plexus is responsible for the generation of earlier components of the evoked potential, while the medial lemniscus and primary somatosensory cortex are not directly involved in the generation of the N13 component.

Explanation

The N13 of the median nerve somatosensory evoked potential is generated in the cervical spinal cord. This is because the N13 component represents the electrical activity generated in the spinal cord when the median nerve is stimulated. The brachial plexus is responsible for the generation of earlier components of the evoked potential, while the medial lemniscus and primary somatosensory cortex are not directly involved in the generation of the N13 component.

140. Functional cortical stimulation is used to localize brain areas that:

Should be preserved during resection

Are most at risk during aneurysm clipping

Are identified before clamping

Can be monitored further by SSEPs

Functional cortical stimulation is used to localize brain areas that should be preserved during resection. This technique involves applying electrical stimulation to specific areas of the brain to map out functional regions, such as those responsible for motor or language function. By identifying these areas, surgeons can avoid damaging critical brain regions during resection surgeries, minimizing the risk of postoperative deficits.

Explanation

Functional cortical stimulation is used to localize brain areas that should be preserved during resection. This technique involves applying electrical stimulation to specific areas of the brain to map out functional regions, such as those responsible for motor or language function. By identifying these areas, surgeons can avoid damaging critical brain regions during resection surgeries, minimizing the risk of postoperative deficits.

141. Which of the following is most consistent with conductive hearing loss?

All waves delayed, normal I-V interpeak interval

Normal latency, decreased amplitude

Wave I amplitude decreased, other waves normal

Wave I delayed, shortened I-V interpeak interval

This answer suggests that all waves are delayed in conductive hearing loss, but the interpeak interval between waves I and V is normal. This means that there is a delay in the transmission of sound from the outer ear to the inner ear, but the transmission between the inner ear and the brainstem is normal. This is consistent with conductive hearing loss, where there is a problem with the conduction of sound through the outer or middle ear.

Explanation

This answer suggests that all waves are delayed in conductive hearing loss, but the interpeak interval between waves I and V is normal. This means that there is a delay in the transmission of sound from the outer ear to the inner ear, but the transmission between the inner ear and the brainstem is normal. This is consistent with conductive hearing loss, where there is a problem with the conduction of sound through the outer or middle ear.

142. Impedance is defined as

Opposition to flow of direct current

Opposition to flow of alternating current

Differential current flow

60 cycle

Impedance is defined as the opposition to the flow of alternating current. It is a measure of how much a circuit resists the flow of AC current. Impedance is composed of both resistance and reactance, where resistance represents the opposition to the flow of direct current and reactance represents the opposition to the flow of alternating current. Therefore, the correct answer is "Opposition to flow of alternating current".

Explanation

Impedance is defined as the opposition to the flow of alternating current. It is a measure of how much a circuit resists the flow of AC current. Impedance is composed of both resistance and reactance, where resistance represents the opposition to the flow of direct current and reactance represents the opposition to the flow of alternating current. Therefore, the correct answer is "Opposition to flow of alternating current".

143. When doing language mapping on the cortex, which is the most common method?

Direct cortical stimulation with a patient under general anesthesia

Direct cortical stimulation with an awake patient

Direct cortical stimulation with a patient who is sleeping, but not under anesthesia

Indirect cortical stimulation with an awake patient

Direct cortical stimulation with an awake patient is the most common method for language mapping on the cortex. This method involves applying electrical stimulation directly to the cortex while the patient is awake and conscious. By doing so, the patient can provide real-time feedback and report any language-related sensations or disruptions experienced during the stimulation. This allows the healthcare professionals to accurately identify the language areas of the brain and minimize the risk of language deficits during neurosurgery.

Explanation

Direct cortical stimulation with an awake patient is the most common method for language mapping on the cortex. This method involves applying electrical stimulation directly to the cortex while the patient is awake and conscious. By doing so, the patient can provide real-time feedback and report any language-related sensations or disruptions experienced during the stimulation. This allows the healthcare professionals to accurately identify the language areas of the brain and minimize the risk of language deficits during neurosurgery.

144. In ABR stimulation, the stimulus polarity that causes a negative pressure and results in a slightly earlier latency is

Alternating clicks

Condensation clicks

Triggered clicks

Rarefaction clicks

In ABR stimulation, rarefaction clicks cause a negative pressure and result in a slightly earlier latency. This means that the rarefaction clicks create a decrease in air pressure, which causes the auditory brainstem response to occur slightly earlier compared to other types of clicks.

Explanation

In ABR stimulation, rarefaction clicks cause a negative pressure and result in a slightly earlier latency. This means that the rarefaction clicks create a decrease in air pressure, which causes the auditory brainstem response to occur slightly earlier compared to other types of clicks.

145. If you observe s-EMG activity in all channels, it is probably due to:

Surgeon error

Mechanical artifact

Nerve root irritation

The patient waking up

If s-EMG activity is observed in all channels, it is likely due to the patient waking up. This can cause muscle contractions and movements, leading to increased s-EMG activity. Surgeon error and nerve root irritation would not necessarily result in activity in all channels, and mechanical artifact refers to external factors causing interference in the s-EMG readings, which would also not explain activity in all channels. Therefore, the most plausible explanation is the patient waking up.

Explanation

If s-EMG activity is observed in all channels, it is likely due to the patient waking up. This can cause muscle contractions and movements, leading to increased s-EMG activity. Surgeon error and nerve root irritation would not necessarily result in activity in all channels, and mechanical artifact refers to external factors causing interference in the s-EMG readings, which would also not explain activity in all channels. Therefore, the most plausible explanation is the patient waking up.

146. Which of the following technical factors could affect pattern reversal visual evoked potential latency and/or amplitude?

Luminance

Contrast

Stimulus rate

All of the above

None of the above

The pattern reversal visual evoked potential is a measure of the brain's response to visual stimuli. The latency and amplitude of this response can be affected by various technical factors. Luminance refers to the brightness of the stimulus, and changes in luminance can impact the brain's response. Contrast, which is the difference in brightness between the stimulus and its background, can also influence the latency and amplitude of the response. Additionally, the rate at which the stimulus is presented can affect the brain's response. Therefore, all of these technical factors (luminance, contrast, and stimulus rate) could potentially impact the pattern reversal visual evoked potential.

Explanation

The pattern reversal visual evoked potential is a measure of the brain's response to visual stimuli. The latency and amplitude of this response can be affected by various technical factors. Luminance refers to the brightness of the stimulus, and changes in luminance can impact the brain's response. Contrast, which is the difference in brightness between the stimulus and its background, can also influence the latency and amplitude of the response. Additionally, the rate at which the stimulus is presented can affect the brain's response. Therefore, all of these technical factors (luminance, contrast, and stimulus rate) could potentially impact the pattern reversal visual evoked potential.

147. Mismatched electrode metals cause:

High impedance reading

60 cycle artifact

Bias potentials from the differential amplification of the different charge of each metal

Less current flow

Mismatched electrode metals cause bias potentials from the differential amplification of the different charge of each metal. When electrodes with different metals are used, their electrical properties can vary, leading to differences in charge and potential between the electrodes. This can result in bias potentials, which can interfere with accurate measurements and create inaccuracies in the recorded data.

Explanation

Mismatched electrode metals cause bias potentials from the differential amplification of the different charge of each metal. When electrodes with different metals are used, their electrical properties can vary, leading to differences in charge and potential between the electrodes. This can result in bias potentials, which can interfere with accurate measurements and create inaccuracies in the recorded data.

148. When is it most appropriate to alert the surgical team of a problem with the monitoring?

After all waveforms are lost

When any change occurs

After a loss of 30% amplitude and 5% latency

After a loss of 55% amplitude

A= too late. B= need to figure out if the change is real or meets alarm criteria (so too soon). C= does not meet alarm criteria. D=alarm criteria is 50% decrease so would tell them one it reaches that criteria or more…. Ideal before the waveform is completely lost

Explanation

A= too late. B= need to figure out if the change is real or meets alarm criteria (so too soon). C= does not meet alarm criteria. D=alarm criteria is 50% decrease so would tell them one it reaches that criteria or more…. Ideal before the waveform is completely lost

149. 50% of visual fibers decussate from the optic nerve at the:

Optic chiasm

Optic disc

Retna

Medulla

The optic chiasm is the correct answer because it is the specific location where approximately 50% of the visual fibers from each optic nerve cross over to the opposite side of the brain. This crossover allows for the integration of visual information from both eyes, leading to binocular vision. The optic disc is the location where the optic nerve exits the eye and does not involve the decussation of visual fibers. The retina is the layer of tissue at the back of the eye that contains the photoreceptor cells responsible for detecting light, but it is not the site of decussation. The medulla is a region in the brainstem and is not directly involved in the decussation of visual fibers.

Explanation

The optic chiasm is the correct answer because it is the specific location where approximately 50% of the visual fibers from each optic nerve cross over to the opposite side of the brain. This crossover allows for the integration of visual information from both eyes, leading to binocular vision. The optic disc is the location where the optic nerve exits the eye and does not involve the decussation of visual fibers. The retina is the layer of tissue at the back of the eye that contains the photoreceptor cells responsible for detecting light, but it is not the site of decussation. The medulla is a region in the brainstem and is not directly involved in the decussation of visual fibers.

150. The following area of the spinal cord is most likely to have the poorest blood supply

Cervical

Thoracic

Lumbar

Sacral

The thoracic region of the spinal cord is most likely to have the poorest blood supply because it is located in the middle of the spinal cord and has a limited blood supply compared to the cervical and lumbar regions. The blood vessels that supply the spinal cord originate from the vertebral arteries and run along the length of the spinal cord. However, the thoracic region has fewer blood vessels branching off from the main supply, which can result in a relatively poorer blood supply to this area.

Explanation

The thoracic region of the spinal cord is most likely to have the poorest blood supply because it is located in the middle of the spinal cord and has a limited blood supply compared to the cervical and lumbar regions. The blood vessels that supply the spinal cord originate from the vertebral arteries and run along the length of the spinal cord. However, the thoracic region has fewer blood vessels branching off from the main supply, which can result in a relatively poorer blood supply to this area.

151. The technologist may furnish the surgeon with

A technical description of the waveforms only

Suggestions as to what might be the cause of the problem

No information regarding the waveform data

Any information requested by the surgeon

The correct answer is "A technical description of the waveforms only." This means that the technologist can provide the surgeon with information specifically related to the waveforms, such as their characteristics or patterns. However, the technologist cannot offer any suggestions about the potential cause of the problem or provide any other information that the surgeon may request.

Explanation

The correct answer is "A technical description of the waveforms only." This means that the technologist can provide the surgeon with information specifically related to the waveforms, such as their characteristics or patterns. However, the technologist cannot offer any suggestions about the potential cause of the problem or provide any other information that the surgeon may request.

152. When placing a simulator probe on the ankle for intraoperative SSEP monitoring of the lower extremities, which of the following is most appropriate?

Never wrap tape or band completely around the ankle

Avoid using a conducting cream or paste

Wait until after the patient is completely draped to place the stimulator

Place both anode and cathode on lateral malleolus

Wrapping tape or band completely around the ankle can impede blood flow and potentially cause harm to the patient. It is important to ensure proper circulation during intraoperative SSEP monitoring.

Explanation

Wrapping tape or band completely around the ankle can impede blood flow and potentially cause harm to the patient. It is important to ensure proper circulation during intraoperative SSEP monitoring.

153. Which of the following monitoring modes is LEAST useful for skull base surgery?

BAEP

Tibial nerve SSEP

Facial nerve monitoring

Cranial nerve monitoring

Tibial nerve SSEP (Somatosensory Evoked Potentials) is the least useful monitoring mode for skull base surgery. BAEP (Brainstem Auditory Evoked Potentials) is important for monitoring the brainstem and auditory nerves during surgery. Facial nerve monitoring is crucial for assessing facial nerve function. Cranial nerve monitoring helps in monitoring the function of multiple cranial nerves involved in skull base surgery. However, tibial nerve SSEP is not directly relevant to skull base surgery as it primarily assesses the function of the lower extremity nerves.

Explanation

Tibial nerve SSEP (Somatosensory Evoked Potentials) is the least useful monitoring mode for skull base surgery. BAEP (Brainstem Auditory Evoked Potentials) is important for monitoring the brainstem and auditory nerves during surgery. Facial nerve monitoring is crucial for assessing facial nerve function. Cranial nerve monitoring helps in monitoring the function of multiple cranial nerves involved in skull base surgery. However, tibial nerve SSEP is not directly relevant to skull base surgery as it primarily assesses the function of the lower extremity nerves.

154. Which of the following is most attenuated by a high frequency filter setting of 35 Hz?

45Hz

30Hz

25Hz

15hZ

A high frequency filter setting of 35 Hz will attenuate frequencies that are higher than 35 Hz. Therefore, the frequency that is closest to 35 Hz, which is 45 Hz, will be most attenuated by this filter setting.

Explanation

A high frequency filter setting of 35 Hz will attenuate frequencies that are higher than 35 Hz. Therefore, the frequency that is closest to 35 Hz, which is 45 Hz, will be most attenuated by this filter setting.

155. The most practical method to assure the integrity of an average is to demonstrate ________ of independently collected averages.

Polarity

Raw data

Latency

Replication

The most practical method to assure the integrity of an average is to demonstrate replication of independently collected averages. Replication involves conducting the same study or experiment multiple times to ensure consistent results. By independently collecting averages and replicating the process, any errors or biases can be identified and minimized, thus ensuring the accuracy and reliability of the average.

Explanation

The most practical method to assure the integrity of an average is to demonstrate replication of independently collected averages. Replication involves conducting the same study or experiment multiple times to ensure consistent results. By independently collecting averages and replicating the process, any errors or biases can be identified and minimized, thus ensuring the accuracy and reliability of the average.

156. The recommended system of electrode placement for half-field stimulation is:

Queen square placement.

Circumference placement.

Half-field system.

Longitudinal bipolar.

Queen square placement is the recommended system of electrode placement for half-field stimulation. This placement involves positioning the electrodes in a specific pattern on the scalp to stimulate only one side of the brain. This technique is commonly used in neurological assessments and research studies to selectively activate specific brain regions and observe their functional responses. Circumference placement, half-field system, and longitudinal bipolar are not the recommended systems for half-field stimulation.

Explanation

Queen square placement is the recommended system of electrode placement for half-field stimulation. This placement involves positioning the electrodes in a specific pattern on the scalp to stimulate only one side of the brain. This technique is commonly used in neurological assessments and research studies to selectively activate specific brain regions and observe their functional responses. Circumference placement, half-field system, and longitudinal bipolar are not the recommended systems for half-field stimulation.

157. EP recording systems should allow averaging of at least

500 trials

400 trials

4,000 trials

8,000 trials

EP recording systems should allow averaging of at least 4,000 trials in order to obtain accurate and reliable results. Averaging a larger number of trials helps to reduce random noise and increases the signal-to-noise ratio, leading to more precise measurements. A higher number of trials also allows for better detection of small or subtle responses, improving the overall sensitivity of the recording system. Therefore, having the capability to average 4,000 trials ensures a higher level of accuracy and sensitivity in EP recordings.

Explanation

EP recording systems should allow averaging of at least 4,000 trials in order to obtain accurate and reliable results. Averaging a larger number of trials helps to reduce random noise and increases the signal-to-noise ratio, leading to more precise measurements. A higher number of trials also allows for better detection of small or subtle responses, improving the overall sensitivity of the recording system. Therefore, having the capability to average 4,000 trials ensures a higher level of accuracy and sensitivity in EP recordings.

158. Which of the following symptoms is most closely correlated with somatosensory evoked potential abnormalities?

Vertigo

Tinnitus

Hemiparesis

Proprioception deficit

Proprioception deficit is the most closely correlated symptom with somatosensory evoked potential abnormalities. Somatosensory evoked potentials are electrical signals generated by the nervous system in response to sensory stimuli. Proprioception refers to the body's ability to sense its position and movement in space. Abnormalities in somatosensory evoked potentials indicate dysfunction in the sensory pathways responsible for proprioception. Therefore, a deficit in proprioception is likely to be closely correlated with abnormalities in somatosensory evoked potentials.

Explanation

Proprioception deficit is the most closely correlated symptom with somatosensory evoked potential abnormalities. Somatosensory evoked potentials are electrical signals generated by the nervous system in response to sensory stimuli. Proprioception refers to the body's ability to sense its position and movement in space. Abnormalities in somatosensory evoked potentials indicate dysfunction in the sensory pathways responsible for proprioception. Therefore, a deficit in proprioception is likely to be closely correlated with abnormalities in somatosensory evoked potentials.

159. EEG changes after cross-clamping a carotid artery occur:

On the same hemisphere to the clamping side.

On the opposite hemisphere to the clamping side.

On both hemispheres.

On either hemisphere.

After cross-clamping a carotid artery, the blood supply to the brain is temporarily interrupted. This interruption can lead to changes in the electrical activity of the brain, as measured by an EEG. The correct answer states that these changes occur on the same hemisphere as the side where the artery is clamped. This is because the blood supply to that hemisphere is directly affected by the clamping, leading to alterations in brain activity.

Explanation

After cross-clamping a carotid artery, the blood supply to the brain is temporarily interrupted. This interruption can lead to changes in the electrical activity of the brain, as measured by an EEG. The correct answer states that these changes occur on the same hemisphere as the side where the artery is clamped. This is because the blood supply to that hemisphere is directly affected by the clamping, leading to alterations in brain activity.

160. Motor impulses correlate with:

Fasiculus cuneatus

Pyramidal tract

Afferent tract

Post central gyrus

Motor impulses correlate with the pyramidal tract. The pyramidal tract is a major pathway in the central nervous system that carries motor impulses from the brain to the spinal cord. It is responsible for controlling voluntary movements of the body. Motor impulses originating from the motor cortex of the brain travel through the pyramidal tract to reach the spinal cord and eventually the muscles, allowing for coordinated movement.

Explanation

Motor impulses correlate with the pyramidal tract. The pyramidal tract is a major pathway in the central nervous system that carries motor impulses from the brain to the spinal cord. It is responsible for controlling voluntary movements of the body. Motor impulses originating from the motor cortex of the brain travel through the pyramidal tract to reach the spinal cord and eventually the muscles, allowing for coordinated movement.

161. When monitoring SSEPs during a spinal manipulation surgery, which of the following post operative deficits might occur without any change in the SSEPs?

Anterior Cord Syndrome

Brown Sequard Syndrome

Rye Syndrome

Epilepsy

Anterior Cord Syndrome: is a medical condition where the anterior spinal artery, the primary blood supply to the anterior portion of the spinal cord, is interrupted, causing ischemia or infarction of the spinal cord in the anterior two-thirds of the spinal cord. It is characterized by loss of motor function below the level of injury, loss of sensations carried by the anterior columns of the spinal cord (pain and temperature), and preservation of sensations carried by the posterior columns (fine touch and proprioception). Anterior spinal artery syndrome is the most common form of spinal cord infarction.
This is because sseps are specific to posterior spinal cord and may not pick up on issues of the anterior spinal cord.

Explanation

Anterior Cord Syndrome: is a medical condition where the anterior spinal artery, the primary blood supply to the anterior portion of the spinal cord, is interrupted, causing ischemia or infarction of the spinal cord in the anterior two-thirds of the spinal cord. It is characterized by loss of motor function below the level of injury, loss of sensations carried by the anterior columns of the spinal cord (pain and temperature), and preservation of sensations carried by the posterior columns (fine touch and proprioception). Anterior spinal artery syndrome is the most common form of spinal cord infarction.
This is because sseps are specific to posterior spinal cord and may not pick up on issues of the anterior spinal cord.

162. Motor impulses correlate with:

Fasiculus cuneatus

Posterior columns

Afferent tract

Pre-central gyrus

Motor impulses correlate with the pre-central gyrus. The pre-central gyrus, also known as the primary motor cortex, is responsible for the initiation and control of voluntary movements. It receives signals from other parts of the brain and sends motor impulses to the muscles, allowing for coordinated movement. The other options listed, such as the fasiculus cuneatus, posterior columns, and afferent tract, are not directly involved in motor impulses.

Explanation

Motor impulses correlate with the pre-central gyrus. The pre-central gyrus, also known as the primary motor cortex, is responsible for the initiation and control of voluntary movements. It receives signals from other parts of the brain and sends motor impulses to the muscles, allowing for coordinated movement. The other options listed, such as the fasiculus cuneatus, posterior columns, and afferent tract, are not directly involved in motor impulses.

163. Which of the following cranial nerves control eye movement?

II, III, IV

III, IV, VI

III, IV, V

IV, V, VI

Cranial nerves III, IV, and VI control eye movement. Cranial nerve III, also known as the oculomotor nerve, innervates the muscles that control most eye movements, including raising the eyelid, constriction of the pupil, and certain movements of the eyeball. Cranial nerve IV, the trochlear nerve, controls the superior oblique muscle, which helps with downward and inward eye movements. Cranial nerve VI, the abducens nerve, innervates the lateral rectus muscle, responsible for outward eye movements. Therefore, these three cranial nerves collectively control the various movements of the eye.

Explanation

Cranial nerves III, IV, and VI control eye movement. Cranial nerve III, also known as the oculomotor nerve, innervates the muscles that control most eye movements, including raising the eyelid, constriction of the pupil, and certain movements of the eyeball. Cranial nerve IV, the trochlear nerve, controls the superior oblique muscle, which helps with downward and inward eye movements. Cranial nerve VI, the abducens nerve, innervates the lateral rectus muscle, responsible for outward eye movements. Therefore, these three cranial nerves collectively control the various movements of the eye.

164. Which cranial nerve destination is Muscles of mastication, with functions of chewing and sensations for touch, pain, and temperature?

V

VI

X

IV

Cranial nerve V, also known as the trigeminal nerve, is responsible for the muscles of mastication, which are involved in chewing. It also carries sensations for touch, pain, and temperature from the face, mouth, and jaw. This nerve has three main branches, each supplying different areas of the face. Therefore, cranial nerve V is the correct answer for this question.

Explanation

Cranial nerve V, also known as the trigeminal nerve, is responsible for the muscles of mastication, which are involved in chewing. It also carries sensations for touch, pain, and temperature from the face, mouth, and jaw. This nerve has three main branches, each supplying different areas of the face. Therefore, cranial nerve V is the correct answer for this question.

165. ___causes traction on the conus medullaris in tethered cord syndrome.

Excessive CSF in the thecal sac

A shortened filum terminale

Ossified PLL

L5-S1 Spondylolisthesis

A shortened filum terminale causes traction on the conus medullaris in tethered cord syndrome.

Explanation

A shortened filum terminale causes traction on the conus medullaris in tethered cord syndrome.

166. The nucleus of an atom contains

Anions

Electrons

Protons

Cations

The nucleus of an atom contains protons. Protons are positively charged particles that are found in the center of the atom, along with neutrons. They are responsible for the overall positive charge of the nucleus, while electrons, which are negatively charged particles, orbit around the nucleus. Anions and cations are charged species that are formed when atoms gain or lose electrons, but they are not found in the nucleus itself.

Explanation

The nucleus of an atom contains protons. Protons are positively charged particles that are found in the center of the atom, along with neutrons. They are responsible for the overall positive charge of the nucleus, while electrons, which are negatively charged particles, orbit around the nucleus. Anions and cations are charged species that are formed when atoms gain or lose electrons, but they are not found in the nucleus itself.

167. What is the 1st step you should take when all waves of the BAEP are lost?

Inform the surgeon immediately.

Ask if anesthesia has changed.

Check the integrity of the stimulus delivery.

Check the blood pressure and body temperature.

When all waves of the BAEP (Brainstem Auditory Evoked Potentials) are lost, the first step should be to check the integrity of the stimulus delivery. This means verifying if the stimulus is being properly delivered to the patient's auditory system. This step is important because if the stimulus is not reaching the patient's auditory system, it can result in the loss of the BAEP waves. By checking the integrity of the stimulus delivery, any issues or malfunctions can be identified and addressed promptly.

Explanation

When all waves of the BAEP (Brainstem Auditory Evoked Potentials) are lost, the first step should be to check the integrity of the stimulus delivery. This means verifying if the stimulus is being properly delivered to the patient's auditory system. This step is important because if the stimulus is not reaching the patient's auditory system, it can result in the loss of the BAEP waves. By checking the integrity of the stimulus delivery, any issues or malfunctions can be identified and addressed promptly.

168. The waveform labeled B can be considered

Near field

Far field

Cortical

Sideways

Waveform B is an afferent volley, propagated potential considered near field

Explanation

Waveform B is an afferent volley, propagated potential considered near field

169. Epidural electrodes are made of platinum because

It is the most durable metal

It is the lowest impedance metal

The chance of allergic reaction is eliminated

Other metals may become toxic when currents are applied

Platinum is used for epidural electrodes because other metals have the potential to become toxic when currents are applied. This means that using other metals could pose a risk to the patient's health. Platinum, on the other hand, does not have this issue and is considered a safe and suitable material for epidural electrodes. It is important to prioritize patient safety and minimize any potential harm that could arise from using electrodes made of metals that may become toxic when exposed to electrical currents.

Explanation

Platinum is used for epidural electrodes because other metals have the potential to become toxic when currents are applied. This means that using other metals could pose a risk to the patient's health. Platinum, on the other hand, does not have this issue and is considered a safe and suitable material for epidural electrodes. It is important to prioritize patient safety and minimize any potential harm that could arise from using electrodes made of metals that may become toxic when exposed to electrical currents.

170. Cochlear microphonics is used to monitor what?

The auditory nerve

The brainstem

The stapes

The end hair cells

Cochlear microphonics is used to monitor the activity of the end hair cells. These cells are responsible for converting sound vibrations into electrical signals that can be transmitted to the auditory nerve. By monitoring the microphonics, which are electrical responses generated by the end hair cells, the function and health of these cells can be assessed. This information is important for understanding and diagnosing hearing disorders and determining the effectiveness of treatments.

Explanation

Cochlear microphonics is used to monitor the activity of the end hair cells. These cells are responsible for converting sound vibrations into electrical signals that can be transmitted to the auditory nerve. By monitoring the microphonics, which are electrical responses generated by the end hair cells, the function and health of these cells can be assessed. This information is important for understanding and diagnosing hearing disorders and determining the effectiveness of treatments.

171. What nerve controls motor function and has sensory distribution in the 4th and 5th metacarpal?

Median

Unler

Posterior tibila

Ulnar

The ulnar nerve is the correct answer because it is responsible for controlling motor function and providing sensory distribution in the 4th and 5th metacarpal.

Explanation

The ulnar nerve is the correct answer because it is responsible for controlling motor function and providing sensory distribution in the 4th and 5th metacarpal.

172. Averaging improves the signal to noise ratio by:

The square of the number of epochs averaged

The square root of number of epochs averaged

50% of the number of epochs averaged

100% of the number of epochs averaged

Averaging improves the signal to noise ratio by the square root of the number of epochs averaged. This means that as the number of epochs averaged increases, the signal to noise ratio improves, but at a decreasing rate. The square root relationship indicates that the improvement in signal to noise ratio becomes less significant as more epochs are averaged.

Explanation

Averaging improves the signal to noise ratio by the square root of the number of epochs averaged. This means that as the number of epochs averaged increases, the signal to noise ratio improves, but at a decreasing rate. The square root relationship indicates that the improvement in signal to noise ratio becomes less significant as more epochs are averaged.

173. Cranial nerve V branches are classified as:

V1, V2, and V3

T1, T2, and T3

A1, A2, and A3

V1, T2, and A3

Cranial nerve V branches are classified as V1, V2, and V3. This classification refers to the three main branches of the trigeminal nerve, which is the fifth cranial nerve. V1, also known as the ophthalmic branch, innervates the forehead, scalp, and the front part of the head. V2, or the maxillary branch, provides sensation to the middle part of the face, including the cheeks and upper lip. V3, the mandibular branch, supplies sensation to the lower part of the face, including the jaw and chin.

Explanation

Cranial nerve V branches are classified as V1, V2, and V3. This classification refers to the three main branches of the trigeminal nerve, which is the fifth cranial nerve. V1, also known as the ophthalmic branch, innervates the forehead, scalp, and the front part of the head. V2, or the maxillary branch, provides sensation to the middle part of the face, including the cheeks and upper lip. V3, the mandibular branch, supplies sensation to the lower part of the face, including the jaw and chin.

174. Which of the following best describes a false negative case?

Evoked potentials disappear but reappear within 15 minutes

Evoked potentials have a greater than 50% de crease of amplitude with no neurological deficit

Evoked potentials remain relatively stable, but postoperative neurologic deficits occur

Evoked potentials disappear during surgery and patient has no postoperative deficit

A false negative case refers to a situation where a test or assessment fails to detect a condition or problem that is actually present. In the context of the given options, the answer "Evoked potentials remain relatively stable, but postoperative neurologic deficits occur" best describes a false negative case. This means that the evoked potentials, which are electrical signals generated by the nervous system, do not show any significant changes during a surgical procedure, but the patient still experiences neurological deficits after the surgery. This indicates that the test failed to detect the potential problem during the procedure, resulting in a false negative outcome.

Explanation

A false negative case refers to a situation where a test or assessment fails to detect a condition or problem that is actually present. In the context of the given options, the answer "Evoked potentials remain relatively stable, but postoperative neurologic deficits occur" best describes a false negative case. This means that the evoked potentials, which are electrical signals generated by the nervous system, do not show any significant changes during a surgical procedure, but the patient still experiences neurological deficits after the surgery. This indicates that the test failed to detect the potential problem during the procedure, resulting in a false negative outcome.

175. What type of responses are subcortical evoked potentials?

Near field

Far field

Visual field

Receptive field

Subcortical evoked potentials are considered far field responses. This is because they originate from neural activity occurring in subcortical structures, such as the brainstem or thalamus, and are recorded at a distance from the source. Far field responses are characterized by their longer latency and lower amplitude compared to near field responses, which are recorded closer to the source of neural activity.

Explanation

Subcortical evoked potentials are considered far field responses. This is because they originate from neural activity occurring in subcortical structures, such as the brainstem or thalamus, and are recorded at a distance from the source. Far field responses are characterized by their longer latency and lower amplitude compared to near field responses, which are recorded closer to the source of neural activity.

176. Primary monitoring modality if the surgery were at C7-C8?

Median

Ulnar

Posterior tibial

CN VIII

The correct answer is Ulnar. The question is asking about the primary monitoring modality if the surgery were at C7-C8. The ulnar nerve is commonly used for intraoperative monitoring during cervical spine surgeries. It is easily accessible and provides reliable information about the integrity of the spinal cord and nerve roots. Monitoring the ulnar nerve can help detect any potential damage or complications during the surgery, making it an important modality for ensuring patient safety.

Explanation

The correct answer is Ulnar. The question is asking about the primary monitoring modality if the surgery were at C7-C8. The ulnar nerve is commonly used for intraoperative monitoring during cervical spine surgeries. It is easily accessible and provides reliable information about the integrity of the spinal cord and nerve roots. Monitoring the ulnar nerve can help detect any potential damage or complications during the surgery, making it an important modality for ensuring patient safety.

177. Reduction of the high frequency filter:

Has no effect on evoked potential latency

Has an unpredictable effect on evoked potential latency

Increases evoked potential latency

Decreases evoked potential latency

The reduction of the high frequency filter increases evoked potential latency. This means that when the high frequency filter is decreased, it causes a delay in the time it takes for the evoked potential to occur. This could be due to the fact that the high frequency filter is responsible for filtering out high frequency noise in the signal, and reducing it may introduce more noise or distortions that can delay the evoked potential response.

Explanation

The reduction of the high frequency filter increases evoked potential latency. This means that when the high frequency filter is decreased, it causes a delay in the time it takes for the evoked potential to occur. This could be due to the fact that the high frequency filter is responsible for filtering out high frequency noise in the signal, and reducing it may introduce more noise or distortions that can delay the evoked potential response.

178. What is meant by the phrase "false negative"?

Data = Good, Patient = Bad

Data = Bad, Patient = Good

Data = Bad, Patient = Bad

Data = Good, Patient = Good

A "false negative" refers to a situation where the test or data incorrectly indicates a negative result or outcome, when in reality it should have been positive. In this case, the data is labeled as "good" while the patient is labeled as "bad." However, the correct answer suggests that the data should have been labeled as "bad" since the patient is actually "bad." This means that there was a false negative, as the data failed to correctly identify the true condition of the patient.

Explanation

A "false negative" refers to a situation where the test or data incorrectly indicates a negative result or outcome, when in reality it should have been positive. In this case, the data is labeled as "good" while the patient is labeled as "bad." However, the correct answer suggests that the data should have been labeled as "bad" since the patient is actually "bad." This means that there was a false negative, as the data failed to correctly identify the true condition of the patient.

179. The generator of N13:

Subcortically generated far-field potential best recorded referentially from scalp electrodes ipsilateral to the stimulated nerve, away from the contralateral N20.

Propagated volley passing under Erbs Point

Stationary (nonpropagated) cervical potential recorded referentially from the dorsal neck probably reflecting mainly post synaptic activity in the cervical cord.

Subcortically generated far-field potential, recorded referentially from scalp electrodes probably reflecting activity in the caudal medial lemniscus.

The correct answer is the stationary (nonpropagated) cervical potential recorded referentially from the dorsal neck probably reflecting mainly post synaptic activity in the cervical cord. This answer is supported by the description provided, which states that this potential is recorded from the dorsal neck and is likely to reflect post synaptic activity in the cervical cord. The other options do not mention the dorsal neck or post synaptic activity in the cervical cord, making them less likely to be the correct answer.

Explanation

The correct answer is the stationary (nonpropagated) cervical potential recorded referentially from the dorsal neck probably reflecting mainly post synaptic activity in the cervical cord. This answer is supported by the description provided, which states that this potential is recorded from the dorsal neck and is likely to reflect post synaptic activity in the cervical cord. The other options do not mention the dorsal neck or post synaptic activity in the cervical cord, making them less likely to be the correct answer.

180. The neuroforamen is:

The opening for the optic nerve to enter the skull

The opening at the base of the skull

The opening within the spinal canal for nerve roots to enter/exit the spinal cord

The opening in the spinal canal for the spinal cord to enter the brainstem

The neuroforamen refers to the opening within the spinal canal through which the nerve roots enter or exit the spinal cord. It is a passageway that allows the nerves to communicate between the spinal cord and the rest of the body. This opening is crucial for the transmission of sensory and motor signals and any obstruction or compression in the neuroforamen can lead to nerve pain or dysfunction.

Explanation

The neuroforamen refers to the opening within the spinal canal through which the nerve roots enter or exit the spinal cord. It is a passageway that allows the nerves to communicate between the spinal cord and the rest of the body. This opening is crucial for the transmission of sensory and motor signals and any obstruction or compression in the neuroforamen can lead to nerve pain or dysfunction.

181. Aliasing is an artifact causing corruption of:

Amplitude

Inter-peak amplitude

Frequency

Inter-peak latency

Aliasing is an artifact that occurs when the frequency of a signal is misrepresented or distorted. It can cause the corruption of the original frequency, leading to inaccuracies in the representation of the signal. Therefore, the correct answer is Frequency.

Explanation

Aliasing is an artifact that occurs when the frequency of a signal is misrepresented or distorted. It can cause the corruption of the original frequency, leading to inaccuracies in the representation of the signal. Therefore, the correct answer is Frequency.

182. Grounding the stimulated limb during a SSEP procedure decreases:

Stimulus artifact/ shock artifact

Stimulus intensity

Stimulating electrode impedances

Spread of stimulating current

Grounding the stimulated limb during a SSEP procedure decreases stimulus artifact/shock artifact. When the limb is grounded, it reduces the interference caused by electrical signals that can be generated during the stimulation process. This interference, known as stimulus artifact or shock artifact, can distort the SSEP signals and make it difficult to accurately interpret the results. Grounding the limb helps to minimize this artifact and improve the quality of the SSEP recordings, allowing for more accurate assessment of nerve conduction and sensory pathways.

Explanation

Grounding the stimulated limb during a SSEP procedure decreases stimulus artifact/shock artifact. When the limb is grounded, it reduces the interference caused by electrical signals that can be generated during the stimulation process. This interference, known as stimulus artifact or shock artifact, can distort the SSEP signals and make it difficult to accurately interpret the results. Grounding the limb helps to minimize this artifact and improve the quality of the SSEP recordings, allowing for more accurate assessment of nerve conduction and sensory pathways.

183. The main arteries that enter the cranium:

MCA and vertebral

Internal carotid and basilar

Jugular and superior vena cava

MCA and ACA

The correct answer is "Internal carotid and basilar." The internal carotid artery and basilar artery are the main arteries that enter the cranium. The internal carotid artery supplies blood to the brain, while the basilar artery is formed by the fusion of the two vertebral arteries and provides blood to the brainstem and cerebellum. These arteries play a crucial role in delivering oxygen and nutrients to the brain, making them essential for its proper functioning.

Explanation

The correct answer is "Internal carotid and basilar." The internal carotid artery and basilar artery are the main arteries that enter the cranium. The internal carotid artery supplies blood to the brain, while the basilar artery is formed by the fusion of the two vertebral arteries and provides blood to the brainstem and cerebellum. These arteries play a crucial role in delivering oxygen and nutrients to the brain, making them essential for its proper functioning.

184. Wave I of the BAEP is a:

Positive potential from the upper pons.

Negative potential from the auditory nerve.

Positive potential from the cochlea.

Positive potential from the ear lobe.

The correct answer is "negative potential from the auditory nerve." This is because the BAEP (Brainstem Auditory Evoked Potential) is an electrical response generated by the auditory nerve and brainstem in response to sound stimulation. During Wave I of the BAEP, the auditory nerve generates a negative potential, which can be detected and measured.

Explanation

The correct answer is "negative potential from the auditory nerve." This is because the BAEP (Brainstem Auditory Evoked Potential) is an electrical response generated by the auditory nerve and brainstem in response to sound stimulation. During Wave I of the BAEP, the auditory nerve generates a negative potential, which can be detected and measured.

185. The primary auditory receptive area at the cortex is the:

Lateral lemniscus

Anterior temporal transverse gyrus

Medial geniculate body

Hippocampus

not-available-via-ai

Explanation

not-available-via-ai

186. Resting Membrane Potential

-7uV

-7mV

-70uV

-70mV

The resting membrane potential refers to the electrical potential difference across the cell membrane when the cell is at rest. It is typically around -70mV, meaning that the inside of the cell is negatively charged compared to the outside. This negative charge is maintained by the active transport of ions across the membrane, such as the sodium-potassium pump. This potential is important for various cellular processes, including the transmission of nerve impulses.

Explanation

The resting membrane potential refers to the electrical potential difference across the cell membrane when the cell is at rest. It is typically around -70mV, meaning that the inside of the cell is negatively charged compared to the outside. This negative charge is maintained by the active transport of ions across the membrane, such as the sodium-potassium pump. This potential is important for various cellular processes, including the transmission of nerve impulses.

187. To record the afferent volley preoperative baseline studies after posterior tibial stimulation, an electrode should be placed on the:

Patella

Metatarsal

Popliteal fossa

Medial malleolus

To record the afferent volley preoperative baseline studies after posterior tibial stimulation, an electrode should be placed on the popliteal fossa. The popliteal fossa is the hollow on the back of the knee where the posterior tibial nerve can be easily accessed. Placing the electrode in this location allows for accurate recording of the nerve's activity during stimulation, providing valuable information for preoperative baseline studies. The other options, such as the patella, metatarsal, and medial malleolus, are not ideal locations for electrode placement in this context.

Explanation

To record the afferent volley preoperative baseline studies after posterior tibial stimulation, an electrode should be placed on the popliteal fossa. The popliteal fossa is the hollow on the back of the knee where the posterior tibial nerve can be easily accessed. Placing the electrode in this location allows for accurate recording of the nerve's activity during stimulation, providing valuable information for preoperative baseline studies. The other options, such as the patella, metatarsal, and medial malleolus, are not ideal locations for electrode placement in this context.

188. If the trials are not reproducible

Turn on your notch filter

Perform an additional trial

Decrase the signal to noise ratio

Discontinue the procedure

Performing an additional trial is the most appropriate action if the trials are not reproducible. By conducting another trial, it allows for the possibility of identifying any inconsistencies or errors in the previous trials. This can help to determine the cause of the non-reproducibility and improve the reliability of the results.

Explanation

Performing an additional trial is the most appropriate action if the trials are not reproducible. By conducting another trial, it allows for the possibility of identifying any inconsistencies or errors in the previous trials. This can help to determine the cause of the non-reproducibility and improve the reliability of the results.

189. Hearing level (HL) is defined as the

Intensity of a long duration sound that has the same amplitude as the peak SPL of a short duration sound

Lowest intensity that an average ear drum can ear

Average threshold intensity of normal-hearing adults

Inverse of the sound pressure level

The correct answer is "Average threshold intensity of normal-hearing adults". This is because hearing level (HL) is a measure of the minimum intensity of sound that can be detected by a person with normal hearing. It represents the average threshold intensity that normal-hearing adults can perceive.

Explanation

The correct answer is "Average threshold intensity of normal-hearing adults". This is because hearing level (HL) is a measure of the minimum intensity of sound that can be detected by a person with normal hearing. It represents the average threshold intensity that normal-hearing adults can perceive.

190. Loss of a unilateral waveform is never a concern as long as wave V is present on the other ear.

True

False

The statement is false because the loss of a unilateral waveform can be a concern even if wave V is present on the other ear. Loss of a unilateral waveform indicates a problem in the auditory pathway, which may require further investigation and treatment. Wave V being present on the other ear does not negate the significance of the loss.

Explanation

The statement is false because the loss of a unilateral waveform can be a concern even if wave V is present on the other ear. Loss of a unilateral waveform indicates a problem in the auditory pathway, which may require further investigation and treatment. Wave V being present on the other ear does not negate the significance of the loss.

191. Cranial nerve X can be monitored using electrodes inserted into the:

Trapezius muscle

Vocalis muscle

Tongue

Soft palate

Cranial nerve X, also known as the vagus nerve, is responsible for controlling various organs in the body, including the muscles involved in speech production. The vocalis muscle is a part of the larynx and is involved in controlling the tension of the vocal cords. By monitoring the activity of the vocalis muscle using electrodes, we can gain insights into the functioning of the vagus nerve and its impact on speech production. This can be useful in diagnosing and treating disorders related to the vagus nerve and vocal cord dysfunction.

Explanation

Cranial nerve X, also known as the vagus nerve, is responsible for controlling various organs in the body, including the muscles involved in speech production. The vocalis muscle is a part of the larynx and is involved in controlling the tension of the vocal cords. By monitoring the activity of the vocalis muscle using electrodes, we can gain insights into the functioning of the vagus nerve and its impact on speech production. This can be useful in diagnosing and treating disorders related to the vagus nerve and vocal cord dysfunction.

192. Which of the following most often causes a temporary threshold shift on the BAEPs during CPA surgery?

Drilling

Bipolar cautery

Warm irrigation

CUSA

During CPA surgery, drilling is the most common cause of a temporary threshold shift on the BAEPs (Brainstem Auditory Evoked Potentials). Drilling involves the use of a high-speed drill to remove bone or tissue, and the vibrations generated by the drill can cause a temporary shift in the auditory threshold. This shift is usually temporary and resolves over time. Bipolar cautery, warm irrigation, and CUSA (Cavitron Ultrasonic Surgical Aspirator) are not typically associated with causing temporary threshold shifts on the BAEPs.

Explanation

During CPA surgery, drilling is the most common cause of a temporary threshold shift on the BAEPs (Brainstem Auditory Evoked Potentials). Drilling involves the use of a high-speed drill to remove bone or tissue, and the vibrations generated by the drill can cause a temporary shift in the auditory threshold. This shift is usually temporary and resolves over time. Bipolar cautery, warm irrigation, and CUSA (Cavitron Ultrasonic Surgical Aspirator) are not typically associated with causing temporary threshold shifts on the BAEPs.

193. Which of the following is a far-field potential?

N20

P14

Wave 1

ERB's point

P14 is a far-field potential because it refers to a specific type of electrical potential that is measured at a distance from its source. Far-field potentials are typically generated by neural activity and can be recorded using electrodes placed on the scalp. N20, Wave 1, and ERB's point do not specifically refer to far-field potentials, making P14 the correct answer.

Explanation

P14 is a far-field potential because it refers to a specific type of electrical potential that is measured at a distance from its source. Far-field potentials are typically generated by neural activity and can be recorded using electrodes placed on the scalp. N20, Wave 1, and ERB's point do not specifically refer to far-field potentials, making P14 the correct answer.

194. While performing a posterior tibial SSEP, hypothermia of the lower extremities is most likely to cause:

Increased L3 - P37 latency

Increased T12- P37 latency

Slowed peripheral conduction velocity

Abnormal prolongation of the P37- N45 complex

Hypothermia of the lower extremities can cause slowed peripheral conduction velocity. Hypothermia can affect nerve function and slow down the transmission of electrical signals along the nerves. This can lead to a delay in the conduction of the nerve impulses, resulting in slowed peripheral conduction velocity. The other options listed, such as increased latencies and abnormal prolongation of the P37-N45 complex, are not directly associated with hypothermia.

Explanation

Hypothermia of the lower extremities can cause slowed peripheral conduction velocity. Hypothermia can affect nerve function and slow down the transmission of electrical signals along the nerves. This can lead to a delay in the conduction of the nerve impulses, resulting in slowed peripheral conduction velocity. The other options listed, such as increased latencies and abnormal prolongation of the P37-N45 complex, are not directly associated with hypothermia.

195. The generator for N13 is the

Cortex

Brainstem

Spinal cord

Peripheral nerve

Spinal cord (C5 spine montage is used)
C5S- Ref= DCN- reflects post synaptic activity in the cervical cord

Explanation

Spinal cord (C5 spine montage is used)
C5S- Ref= DCN- reflects post synaptic activity in the cervical cord

196. The effect of hypotension on the evoked potential is:

Increased amplitude, decreased latency

Decreased amplitude, increased latency

Variable changes in amplitude, increased latency

Decreased amplitude, variable changes in latency

Hypotension…think low blood pressure… think hypoperfusion… we’re going to see decreased amplitudes and increased latencies

Explanation

Hypotension…think low blood pressure… think hypoperfusion… we’re going to see decreased amplitudes and increased latencies

197. Periods of repetitive synchronous potentials that may represent neuro insult and potential nerve damage:

Bursts

Trains

Discharges

Firing

Trains of repetitive synchronous potentials can indicate neuro insult and potential nerve damage. This suggests that there is a repetitive pattern of synchronized electrical activity in the nerves, which may be abnormal and indicative of underlying damage or injury. The term "trains" refers to a series of these synchronous potentials occurring in succession, further supporting the idea that there is a repetitive and potentially harmful pattern of nerve activity.

Explanation

Trains of repetitive synchronous potentials can indicate neuro insult and potential nerve damage. This suggests that there is a repetitive pattern of synchronized electrical activity in the nerves, which may be abnormal and indicative of underlying damage or injury. The term "trains" refers to a series of these synchronous potentials occurring in succession, further supporting the idea that there is a repetitive and potentially harmful pattern of nerve activity.

198. Stimulus rates that are not an integral of 60 Hz are suggested for EP studies:

Because A/D converters operate at 60 Hz.

Because the central nervous system tolerates these frequencies poorly.

To avoid synchronization problems with averaging computers.

To avoid 60 Hz from occurring in the averaged waveform.

The correct answer is to avoid 60 Hz from occurring in the averaged waveform. This means that using stimulus rates that are not a multiple of 60 Hz helps prevent any interference or synchronization issues with the averaging computers. If the stimulus rates were multiples of 60 Hz, it could lead to the occurrence of the 60 Hz frequency in the averaged waveform, which would distort the results and make them less reliable. Therefore, using non-integral stimulus rates helps ensure the accuracy of the averaged waveform by avoiding the presence of the 60 Hz frequency.

Explanation

The correct answer is to avoid 60 Hz from occurring in the averaged waveform. This means that using stimulus rates that are not a multiple of 60 Hz helps prevent any interference or synchronization issues with the averaging computers. If the stimulus rates were multiples of 60 Hz, it could lead to the occurrence of the 60 Hz frequency in the averaged waveform, which would distort the results and make them less reliable. Therefore, using non-integral stimulus rates helps ensure the accuracy of the averaged waveform by avoiding the presence of the 60 Hz frequency.

199. A BAEP reveals an interpeak latency of 2ms between waves I and III and an interpeak latency of 3.57 between waves III and V. Subsequently, MRI detects a lesion

In the transverse gyrus of the temporal lobe

Between the superior olivary complex and the distal portion of CN VIII

Between the pons and the upper brainstem

The tympanic membrane

The interpeak latency between waves III and V in a BAEP (Brainstem Auditory Evoked Potential) test is typically around 3-5 ms. In this case, the interpeak latency is 3.57 ms, which falls within the normal range. However, the interpeak latency between waves I and III is only 2 ms, which is shorter than expected. This suggests that there may be a lesion or abnormality in the auditory pathway between the pons and the upper brainstem, causing a delay in the transmission of the auditory signals. Therefore, the correct answer is "Between the pons and the upper brainstem."

Explanation

The interpeak latency between waves III and V in a BAEP (Brainstem Auditory Evoked Potential) test is typically around 3-5 ms. In this case, the interpeak latency is 3.57 ms, which falls within the normal range. However, the interpeak latency between waves I and III is only 2 ms, which is shorter than expected. This suggests that there may be a lesion or abnormality in the auditory pathway between the pons and the upper brainstem, causing a delay in the transmission of the auditory signals. Therefore, the correct answer is "Between the pons and the upper brainstem."

200. An 8-bit converter will have a range of ___ steps.

64

128

256

512

An 8-bit converter will have a range of 256 steps because an 8-bit converter uses 8 bits to represent the analog signal. Each bit can have two possible values (0 or 1), so with 8 bits, there are a total of 2^8 = 256 possible combinations. Each combination represents a different step in the range of the converter.

Explanation

An 8-bit converter will have a range of 256 steps because an 8-bit converter uses 8 bits to represent the analog signal. Each bit can have two possible values (0 or 1), so with 8 bits, there are a total of 2^8 = 256 possible combinations. Each combination represents a different step in the range of the converter.

Cnim Board Prep