Cnim Board Prep

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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".

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.

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.

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.

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.

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.

the somatosensory system carries information TOWARDS the brain

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."

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.

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.

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."

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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".

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.

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.

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.

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.