Cnim Abret Practice Questions

An interbody cage is a device used in spinal surgery to restore the height of a lost disc space. When a disc in the spine degenerates or is damaged, it can lead to a loss of disc height, causing instability and compression of nearby nerves. By placing an interbody cage in the disc space, it helps to restore the height and alignment of the spine, reducing pressure on the nerves and promoting fusion between the vertebral bodies. This helps to alleviate pain, improve stability, and restore normal function in the spine.

Spondylitis refers to the inflammation of a vertebrae or vertebral joint. This condition can cause pain, stiffness, and swelling in the affected area. It is often caused by an infection or an autoimmune disease such as ankylosing spondylitis. Treatment for spondylitis may include medication, physical therapy, and lifestyle modifications to manage pain and improve mobility.

The N20 responses are generated from the sensory cortex contralateral to the stimulation side. This means that when a stimulus is applied to one side of the body, the sensory information is processed in the sensory cortex on the opposite side of the brain.

Bell's Palsy is a condition that causes temporary weakness or paralysis of the muscles on one side of the face. The facial nerve (CN VII) controls the muscles of facial expression, including smiling, frowning, and closing the eyes. Therefore, when someone has Bell's Palsy, the function of the facial nerve (CN VII) is compromised, leading to the characteristic facial drooping on one side.

Bloodborne pathogens are infectious microorganisms that are present in the blood and can cause diseases when transmitted from one person to another through exposure to infected blood. Hepatitis B is a viral infection caused by the hepatitis B virus (HBV) and is one of the diseases that can be transmitted through bloodborne pathogens. It affects the liver and can lead to chronic liver disease, liver cancer, and even death if left untreated. Asthma and cystic fibrosis are not caused by bloodborne pathogens, while TB (tuberculosis) is primarily transmitted through the air and not through blood. Therefore, the correct answer is Hepatitis B.

The lamina is the part of the spine that is removed in order to place an epidural electrode. The lamina is a thin, flat bone that forms the back part of the spinal canal. By removing the lamina, the surgeon can access the epidural space and place the electrode for pain management or other purposes. The other options listed, such as the vertebral body, foramen, and intervertebral disc, are not directly involved in the placement of an epidural electrode.

The N18 subcortical response is classified as a far field response. Far field responses refer to electrical activity generated by neural structures that are located at a distance from the recording electrodes. In the case of the N18 response, it is generated by subcortical structures such as the brainstem. This distinction is important because far field responses are less affected by artifacts and noise compared to near field responses, which originate from neural structures closer to the recording electrodes.

Intraoperative facial nerve monitoring was developed in response to a high occurrence of facial nerve weakness after acoustic nerve surgeries. This monitoring technique allows surgeons to assess the function of the facial nerve in real-time during the surgery, helping to prevent or minimize nerve damage and potential post-operative complications.

CN VII (Facial nerve) EMG should be included in addition to BAER for vestibular schwannoma surgery because the facial nerve is at risk of injury during the procedure. Monitoring the facial nerve with EMG helps to identify any changes or damage to the nerve during surgery, allowing for immediate intervention and minimizing the risk of facial nerve dysfunction or paralysis. This modality helps the surgeon to ensure the preservation of facial nerve function and improve patient outcomes.

Upper limb somatosensory evoked potentials (SSEPs) are transmitted via the fasciculus cuneatus. The fasciculus cuneatus is a white matter tract in the spinal cord that carries sensory information from the upper limbs to the brain. It is responsible for transmitting touch, vibration, and proprioceptive information from the upper limbs to the somatosensory cortex. The other options, including the fasciculus gracilis, nucleus gracilis, and corticospinal fibers, are not involved in the transmission of upper limb SSEPs.

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If the amplifier gets saturated during the exposure part of the surgery, resetting the amplifier can be a possible solution. By resetting the amplifier, it can help to resolve any technical issues or errors that may have caused the saturation. This can help to restore the amplifier to its normal functioning state and ensure that it is able to accurately amplify the signals during the surgery.

The cerebellum is not part of the brainstem. The brainstem consists of three structures: the pons, medulla, and midbrain. The cerebellum is located above the brainstem and is responsible for coordinating movement, balance, and posture. While it is connected to the brainstem, it is considered a separate structure.

The ACNS guidelines recommend stimulating the posterior tibial nerve for lower limb SSEP. This nerve is responsible for sensory innervation of the sole of the foot and its stimulation can provide accurate and reliable signals for assessing the function of the lower limb. Stimulation of the peroneal nerve, sciatic nerve, or median nerve would not be appropriate for lower limb SSEP as they do not specifically target the sensory innervation of the lower limb.

The correct answer is 50% decrease in amplitude and/or 10% increase in latency. This means that if there is a 50% decrease in the amplitude of the SSEP signal or a 10% increase in the latency (delay) of the signal, it is considered a warning criteria for SSEP changes. These changes may indicate a potential problem or abnormality in the sensory evoked potentials.

The trans-labyrinthine approach surgery involves sacrificing the Vestibulocochlear nerve (CN VIII). This nerve is responsible for transmitting auditory and balance information from the inner ear to the brain. Sacrificing this nerve is necessary in certain cases to access and remove tumors located in the inner ear or the cerebellopontine angle. By sacrificing CN VIII, the patient may experience permanent hearing loss and balance problems on the affected side.

Apraxia is a neurological condition that affects a person's ability to perform purposeful movements, despite having the physical ability to do so. It primarily affects speech and motor functions. Speech apraxia causes difficulty in planning and coordinating the movements needed for speech production, resulting in problems with articulation and pronunciation. Motor apraxia, on the other hand, affects the ability to perform skilled movements, such as buttoning a shirt or using utensils. Therefore, if a patient is diagnosed with apraxia, their speech and motor functions will be affected.

Selective dorsal root rhizotomy is a surgical procedure used to treat spasticity. Spasticity is a condition characterized by muscle stiffness and tightness, often caused by damage to the brain or spinal cord. This procedure involves selectively cutting certain nerve roots in the spinal cord to reduce the abnormal signals that cause spasticity. By targeting and eliminating these abnormal signals, selective dorsal root rhizotomy can help improve muscle function and reduce spasticity in patients.

Multi-pulse stimulation is optimal for activation of alpha motor neurons to produce compound muscle action potentials (CMAP) in distal muscles. Alpha motor neurons are responsible for innervating skeletal muscles and are capable of generating action potentials that result in muscle contraction. By delivering multiple pulses of stimulation, it is possible to recruit a larger number of motor units and generate a stronger muscle contraction, leading to a larger CMAP response. Therefore, the activation of alpha motor neurons through multi-pulse stimulation is the most effective method for producing CMAP in distal muscles.

The disadvantage of synchronous stimulation is that it is unable to identify a unilateral change. This means that if there is a change or abnormality occurring on one side of the patient's body, synchronous stimulation will not be able to detect it. This limitation can be problematic as it may lead to a failure in accurately diagnosing or monitoring certain conditions or abnormalities in the patient.

Accidental extubation is one of the major risks of a wake-up test. This occurs when the endotracheal tube, which is used to maintain an open airway during surgery, is unintentionally removed. Accidental extubation can lead to serious complications, such as airway obstruction, aspiration of stomach contents, and decreased oxygenation. It is important to closely monitor the patient during a wake-up test to prevent this potential risk.

The ratio of an output voltage to an input voltage of an amplifier is known as gain. Gain is a measure of the amplification or multiplication factor of the input signal. It indicates how much the input signal is amplified by the amplifier. A higher gain value means a larger output voltage compared to the input voltage, while a lower gain value means a smaller output voltage compared to the input voltage. Therefore, gain is the correct answer in this context.

Flash Visual Evoked Potentials (FVEP) are evoked responses that are produced by unpatterned visual stimulation. This means that when a flash of light is presented to the visual system, it elicits a response that can be measured through electrodes placed on the scalp. FVEPs are commonly used in clinical settings to assess the function of the visual system, including the optic nerve and visual cortex. This technique allows for the evaluation of visual pathway integrity and can help diagnose conditions such as optic neuritis, multiple sclerosis, and other visual disorders.

Good insulating materials are those that prevent or inhibit the flow of electric current. Glass, rubber, and wood are all examples of materials that have high resistance and therefore act as insulators. These materials do not easily allow the movement of electrons, making them suitable for applications where electrical conductivity needs to be avoided. Therefore, the correct answer is "All of the above" as all three materials listed are good insulators.

EMG train activity refers to the electrical activity recorded from the facial nerve during surgical procedures. Nerve traction, cold irrigation, and heating of the nerve are all potential causes of this activity. Nerve traction occurs when the nerve is stretched or pulled during the procedure, leading to increased electrical activity. Cold irrigation involves the use of cold fluids during surgery, which can also stimulate the nerve and cause increased activity. Heating of the nerve can occur due to the use of electrosurgical devices or other sources of heat, leading to further electrical activity. Therefore, all of these factors can contribute to EMG train activity during surgical procedures involving the facial nerve.

The statement suggests that ERG (Electroretinogram) can be absent even if there is an inactive FVEP (Flash Visual Evoked Potential). This means that the electrical activity in the retina may not be detected by the ERG test, even though the visual pathway to the brain is not functioning properly, as indicated by the inactive FVEP. Therefore, the statement is true.

A microvascular decompression (MVD) is a surgical procedure that involves placing a teflon pad between an artery and a nerve to separate them. This is done to relieve pressure on the nerve caused by the artery. By separating the artery from the nerve, the compression on the nerve is alleviated, reducing symptoms such as pain or dysfunction. This procedure is commonly performed to treat conditions such as trigeminal neuralgia or hemifacial spasm.

The statement is stating that TCD (Transcranial Doppler) is used for measuring blood flow velocity, not blood flow. This means that TCD is not able to measure the actual volume of blood flow, but rather the speed or velocity at which the blood is flowing. Therefore, the correct answer is "True" because it accurately reflects the information provided in the statement.

Checking the electrode impedance for electrocorticography (ECoG) is done to assess the integrity of the electrodes. Impedance refers to the resistance to the flow of electrical current, and by measuring the impedance of the electrodes, it can be determined if they are functioning properly. This is important because any issues with the electrodes can affect the quality and accuracy of the ECoG recordings. Therefore, checking the integrity of the electrodes is a crucial step in ensuring the reliability of the ECoG data.

Lumbar Potential (LP) is a stationary potential, meaning it does not propagate or move from one place to another. This suggests that LP remains localized in the lumbar region and does not spread throughout the body. Therefore, the statement "Lumbar Potential (LP) is a stationary (non-propagated) potential" is true.

A very low current as small as 10mV that can be lethal to the patient if it passes through the heart is known as microshock. This term is used to describe an electrical shock that occurs within the body, specifically affecting the heart. The small current may not be felt by the patient, but it can disrupt the normal electrical signals in the heart, potentially leading to cardiac arrest or other serious complications. Therefore, it is important to be aware of the potential dangers of microshock and take appropriate precautions to prevent it.

According to the ACNS guidelines for short latency SSEP, the recommended nerve to stimulate for upper limb SSEP is the median nerve.

Ohm's law states that the voltage across a conductor is directly proportional to the current flowing through it, with the constant of proportionality being the resistance of the conductor. This can be mathematically expressed as V=IR, where V is the voltage, I is the current, and R is the resistance. This equation shows that the voltage is equal to the product of the current and the resistance.

Pattern Shift VEPs (PVEP) are affected by drowsiness. This means that when a person is feeling drowsy or sleepy, it can impact their Pattern Shift VEPs. This could result in changes or abnormalities in the brain's response to visual stimuli, leading to altered or impaired visual perception. Therefore, the statement "Pattern Shift VEPs (PVEP) are affected by drowsiness" is true.

The masseter muscle is one of the main muscles responsible for the movement of the jaw. Cranial nerve V, also known as the trigeminal nerve, innervates the muscles of mastication, including the masseter muscle. Therefore, needle electrodes can be placed in the masseter muscle to monitor the activity of cranial nerve V.

The correct answer is C5-T1. The median nerve is formed by the spinal roots at the level of C5-T1. These spinal roots originate from the brachial plexus, which is a network of nerves that innervates the upper limb. The median nerve provides motor and sensory innervation to the muscles and skin of the forearm and hand.

The ulnar nerve is formed by the spinal roots at the C8-T1 level. This means that the nerve fibers from the eighth cervical (C8) and first thoracic (T1) spinal nerves come together to create the ulnar nerve.

The spinal cord is supplied with blood by one anterior and two posterior arteries. These arteries provide essential oxygen and nutrients to the spinal cord, ensuring its proper functioning. The anterior artery supplies blood to the front of the spinal cord, while the two posterior arteries supply blood to the back. This arrangement helps maintain a consistent blood flow and supports the overall health of the spinal cord.

Selective dorsal rhizotomy is the procedure in which lower extremity triggered EMG is used to identify rootlets that can cause spasticity. This procedure involves cutting selectively the sensory nerve fibers in the spinal cord that are responsible for transmitting abnormal signals to the muscles, thus reducing spasticity. By using triggered EMG, the surgeon can identify the specific rootlets that are causing the spasticity and selectively cut them, leading to improved motor function and reduced muscle stiffness.

Sodium amytal is used for performing the WADA test. The WADA test, also known as the intracarotid amobarbital procedure (IAP), is a medical test used to assess language and memory functions in the brain. During the test, sodium amytal is injected into the carotid artery to temporarily anesthetize one side of the brain. This allows the healthcare provider to evaluate the functions of the other side of the brain and determine the language and memory dominance.

During cortical mapping, the median nerve should be stimulated contralaterally. This means that the nerve on the opposite side of the brain from the area being mapped should be stimulated. Stimulation of the median nerve on the same side as the mapping could lead to inaccurate results.

The presence of delta activity in an infant below one year of age is considered normal. Delta activity refers to slow brain waves that are typically seen during deep sleep. In infants, it is common for their sleep patterns to include a significant amount of deep sleep, which is characterized by delta activity. As the infant grows older, their sleep patterns will gradually change, and the amount of delta activity will decrease. Therefore, the presence of delta activity in an infant below one year of age is considered a normal part of their brain development.

TIVA stands for Total IntraVenous Anesthesia, which refers to a method of administering anesthesia solely through intravenous means, without the use of inhaled anesthetics. This technique is commonly used in surgical procedures and provides a continuous and controlled level of anesthesia throughout the operation.

The normal resting membrane potential for a typical neuron is -70mV. This means that the inside of the neuron is 70 millivolts more negative than the outside. This resting potential is maintained by the balance of ions inside and outside the neuron, with more sodium ions outside and more potassium ions inside. This potential is important for the proper functioning of the neuron and allows for the generation and transmission of electrical signals.

The responses recorded by an epidural electrode due to an indirect activation of corticospinal tract are known as I-Wave.

If a person feels a shock from the IOM (Intraoperative Monitoring) equipment, the first step they should take is to disconnect themselves from the equipment. This is important to ensure their safety and prevent further harm. Informing the surgeon and circulation nurse about the incident should also be done, but the immediate action of disconnecting is crucial to prevent any further harm or injury. Additionally, stopping all stimulation to the patient may be necessary, but it is not the first step to take in this situation.

The electrical charge stored by a capacitor is known as capacitance. Capacitance is a measure of how much charge a capacitor can store per unit voltage. It is determined by the physical characteristics of the capacitor, such as the size of the plates and the distance between them. Impedance, inductance, and amperage are not related to the electrical charge stored by a capacitor.

The correct answer is CN III (Oculomotor). CN III is responsible for supplying most of the muscles of the eye. It controls the movement of the eyelid and the muscles that allow the eye to move up, down, and inward. CN II (Optic) is responsible for vision, CN IV (Trochlear) controls the superior oblique muscle, and CN VI (Abducens) controls the lateral rectus muscle. However, CN III is the main cranial nerve that supplies the majority of the eye muscles.

Both terms, Cerebrovascular accident (CVA) and Transient Ischemic Attack (TIA), are other terms for stroke that might be found in the patient history. It is important to be aware of these terms because they indicate different types of strokes and can impact the appropriate response and treatment for the patient. A CVA refers to a more severe and permanent stroke, while a TIA is a temporary episode of stroke-like symptoms that resolve on their own. Understanding these terms helps healthcare professionals make informed decisions for the patient's care.

During left carotid endarterectomy (CEA) surgery, the cortical somatosensory evoked potential (SSEP) at risk will be for the right median nerve. This is because the left carotid endarterectomy involves the surgical removal of plaque from the left carotid artery, which can potentially affect the blood supply to the brain. SSEP monitoring is used during the surgery to assess the integrity of the sensory pathways in the brain. Since the right median nerve sends sensory signals to the brain, any disruption in blood supply during the surgery can lead to changes in the cortical SSEP specifically for the right median nerve.

If the anterior cerebral artery is occluded, it can lead to a decrease in blood supply to the brain, specifically the areas supplied by this artery. This can result in impairment or loss of function in the corresponding brain regions. PTN SSEP (Posterior Tibial Nerve Somatosensory Evoked Potential) responses are used to assess the integrity of the sensory pathways in the brain. Since the occlusion of the anterior cerebral artery affects blood supply to the brain, it can disrupt the normal functioning of the sensory pathways and thus affect the PTN SSEP responses. Therefore, the statement is true.

The sudden loss in ipsilateral ERB's point and contralateral N20 response suggests a potential issue with the arm positioning. It is important to check if the patient's arm is properly positioned, as improper positioning can lead to nerve compression or stretching, resulting in a loss of response. By checking the arm positioning, any issues can be identified and corrected, potentially restoring the response.

The correct answer is the Contralateral Somatosensory Cortex. When the median nerve is stimulated, it sends signals to the somatosensory cortex on the opposite side of the body. This leads to the generation of a negative N20 peak in the contralateral somatosensory cortex.

Damage to the L4-S1 nerve roots may result in foot drop. The L4-S1 nerve roots are responsible for innervating the muscles that control dorsiflexion of the foot, which is necessary for lifting the foot and toes off the ground during walking. Damage to these nerve roots can lead to weakness or paralysis of the muscles involved in dorsiflexion, causing the foot to drag or drop when walking. This can significantly impair a person's ability to walk normally and may require assistive devices or rehabilitation to regain function.

The recommended bandpass filter settings for EEG recording are 1-70Hz. This range allows for the filtering of unwanted noise and artifacts while preserving the relevant frequency components of the EEG signal. Frequencies below 1Hz and above 70Hz are typically not of interest in EEG recordings and can be filtered out to improve signal quality.

Impedance is defined as the opposition to an alternating current. It refers to the total resistance, inductance, and capacitance in an electrical circuit. When an alternating current flows through a circuit, the impedance restricts its flow by resisting or impeding its passage. This opposition is caused by the combined effect of resistors, inductors, and capacitors in the circuit. Therefore, the correct answer is "Opposition to an alternating current."

A partial dislocation of a joint is known as sublaxation. This term is used to describe a condition where the joint is not completely dislocated but is partially out of its normal position. Sublaxation can cause pain, instability, and limited range of motion in the affected joint. It is important to seek medical attention for sublaxation to prevent further damage and to receive appropriate treatment.

The cortical grid is made of platinum.

Anodal stimulation refers to the process of applying a positive electric charge to an electrode, which results in the depolarization of neurons and an increase in their excitability. This type of stimulation is commonly used in transcranial direct current stimulation (tDCS) to enhance cognitive functions or treat certain neurological disorders. In contrast, cathodal stimulation involves the application of a negative charge to an electrode, leading to hyperpolarization and a decrease in neuronal excitability. Therefore, MEPs (motor evoked potentials) are known as anodal stimulation rather than cathodal stimulation.

The active electrode is usually placed on the scalp 2cm behind the vertex (Cz) for lower limb SSEP. The vertex (Cz) is a specific location on the scalp that is commonly used as a reference point in electroencephalography (EEG) studies. Placing the electrode 2cm behind the vertex ensures accurate recording of the lower limb somatosensory evoked potentials (SSEP) by capturing the electrical activity from the relevant neural pathways. The other options, Fpz, C3', and C4', are not the recommended placement sites for lower limb SSEP.

Penfield's technique refers to the use of bipolar stimulation of the exposed motor cortex using a bipolar probe with 50-60Hz stimulation. This technique is named after Wilder Penfield, a Canadian neurosurgeon who developed it in the 1930s. It involves applying small electrical currents to specific areas of the motor cortex to map out the functional areas of the brain and identify the motor representation of different body parts. This technique has been widely used in neurosurgery to guide the removal of brain tumors and to identify and preserve critical motor functions.

Loss of subcortical and cortical SSEP responses but intact ERB's point response suggests an injury in the brainstem or thalamus. SSEP responses originate from the sensory pathways in the brain, including the subcortical and cortical regions. If these responses are lost, it indicates a disruption in these areas. On the other hand, ERB's point response is a test for the integrity of the brachial plexus, which is a network of nerves in the shoulder and arm. If this response is intact, it suggests that the injury is not in the brachial plexus. Therefore, the most likely location of the injury is in the brainstem or thalamus.

The generator of Wave I of the BAEP response is the Distal Auditory Nerve. This is because Wave I represents the initial auditory nerve response to sound stimuli. The Distal Auditory Nerve is responsible for transmitting auditory information from the cochlea to the brainstem.

The minimum Common Mode Rejection Ratio (CMRR) of a differential amplifier should be 10,000:1 or 80db. CMRR is a measure of how well a differential amplifier rejects common mode signals, which are signals that appear equally on both inputs. A higher CMRR indicates better rejection of these common mode signals. Therefore, a minimum CMRR of 10,000:1 or 80db ensures that the differential amplifier can effectively reject common mode noise and interference.

The tapered, lower end of the spinal cord is called the conus medullaris. This is the terminal portion of the spinal cord, located at the level of the first or second lumbar vertebra. It marks the end of the spinal cord proper and gives rise to the cauda equina, a bundle of nerves that continues down the vertebral canal. The conus medullaris is an important anatomical landmark in the spinal cord and is involved in the transmission of sensory and motor information.

The anal sphincter muscles are supplied by the S2-S3-S4 nerve roots. These nerve roots are responsible for innervating the muscles that control the opening and closing of the anus. Dysfunction or damage to these nerve roots can result in issues with bowel control and continence.

Unequal electrode impedances can result in increased noise because when the impedances of the electrodes are not balanced, it can lead to uneven electrical signals being picked up by the electrodes. This can introduce interference and noise into the signal being measured or recorded. The unequal impedances can cause variations in the voltage levels, resulting in a distorted and noisy signal. Therefore, it is important to have balanced electrode impedances to minimize noise and ensure accurate measurements.

Dilantin is a medication commonly used for treating seizures. It belongs to a class of drugs called anticonvulsants, which work by stabilizing electrical activity in the brain to prevent seizures. Dilantin is often prescribed for various types of seizures, including generalized tonic-clonic seizures, complex partial seizures, and seizures caused by epilepsy or brain injury. It is not used for treating pain, allergies, or as a stimulant.

The N34 subcortical response is categorized as a far field response. Far field responses refer to electrical activity that originates from a distant source and can be recorded at a separate location. In the case of the N34 subcortical response, it is an electrical signal that is generated in the brain and can be measured at a location away from the source. This categorization helps in understanding the nature and characteristics of the response in terms of its generation and recording.

D-Wave responses are not sensitive to anesthetic agents.

I-Wave responses are very sensitive to anesthetic agents, meaning that the electrical activity in the brain, known as I-Wave responses, can be significantly affected by the presence of anesthetics. This sensitivity suggests that anesthetics can have a strong impact on the brain's electrical signals and potentially alter brain function during anesthesia.

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The correct answer is placing a cortical grid across the central sulcus. The central sulcus is a prominent fold in the cerebral cortex that separates the frontal lobe from the parietal lobe. By placing a cortical grid across the central sulcus, researchers can map and study the different regions of the cerebral cortex, including the sensory and motor cortex. This allows them to understand the functions and organization of the brain in relation to different areas of the cortex.

The best time to set baselines is after the patient has been induced with anesthesia and before the incision is made. This allows for accurate measurements and comparisons to be made before any surgical manipulation or intervention occurs. By setting baselines at this specific time, healthcare professionals can establish a starting point for monitoring the patient's vital signs and other parameters throughout the surgical procedure.

Intracranial stimulation of the facial nerve (CN VII) produces a muscle response at a latency of approximately 7ms. Latency refers to the time it takes for a response to occur after a stimulus is applied. In this case, when the facial nerve is stimulated within the brain, it takes approximately 7ms for the muscle response to occur.

The maximum allowable chassis leakage current is less than 300uA RMS with ground open. This means that the amount of current that can leak from the chassis of the device to the ground when it is open should be less than 300uA RMS. This is an important specification to ensure the safety and proper functioning of the device.

Inductance refers to the opposition or resistance to a change in current flow in a circuit. It is caused by the presence of an inductor, which stores energy in the form of a magnetic field. When the current flowing through the inductor changes, the magnetic field also changes, creating a counter electromotive force that opposes the change in current. Therefore, inductance can be considered as the opposition to change in current flow.

Subdermal needle electrodes are inserted beneath the skin, while scalp electrodes are placed on the surface of the scalp. The impedance of an electrode refers to its resistance to the flow of electrical current. Since subdermal needle electrodes are inserted deeper into the tissue, they encounter more resistance compared to scalp electrodes, which are closer to the surface. Therefore, the statement that the impedances of subdermal needle electrodes are typically higher than scalp electrodes is true.

The main components of Flash ERG are the A-Wave and B-Wave. The A-Wave represents the initial negative deflection of the ERG response, while the B-Wave represents the subsequent positive deflection. These waves are important in evaluating the function of the retina and can provide information about the health and integrity of the photoreceptor cells.

The femoral nerve is formed by the spinal roots at the level of L2-L4. This means that the nerve is derived from the second, third, and fourth lumbar vertebrae in the spinal column. These spinal roots come together to form the femoral nerve, which is responsible for providing sensation to the front of the thigh and inner leg, as well as controlling the muscles that extend the leg at the knee joint.

The monopolar electrode for pedicle screw stimulation should be plugged into the cathode because the cathode is the negatively charged electrode. When the cathode is connected to the monopolar electrode, it allows for the flow of electrons from the electrode to the surrounding tissue. This flow of electrons stimulates the nerves and muscles in the area, providing therapeutic benefits. Plugging the electrode into the anode, which is the positively charged electrode, would result in the opposite effect and may not produce the desired stimulation.

The vertical resolution of an IOM machine depends on the size of the analog to digital converter (ADC). The ADC is responsible for converting the analog signals from the patient into digital signals that can be processed by the machine. The size of the ADC determines the number of bits used to represent the digital signal, which in turn affects the resolution of the signal. A larger ADC size allows for more precise and detailed representation of the analog signal, resulting in a higher vertical resolution.

When an injection of Pavulon is given to a patient during surgery, it will affect EMG (electromyography) and TcMEP (transcranial motor evoked potentials). Pavulon is a neuromuscular blocking agent that causes temporary paralysis by blocking the transmission of nerve signals to the muscles. This will result in a decrease or absence of muscle activity, which can be detected by EMG. TcMEP measures the electrical activity of the muscles in response to stimulation of the motor cortex, and since Pavulon affects the transmission of nerve signals, it will also affect TcMEP.

The abductor hallucis brevis (AHB) muscle is the best muscle used for recording lower limb TcMEP (Transcranial Motor Evoked Potentials) because it is located in the foot and is innervated by the tibial nerve. This muscle is responsible for the abduction of the big toe, making it an ideal choice for assessing the function of the lower limb during TcMEP recordings.

To avoid electrode polarization in the operating room, it is recommended to use electrodes with the same identical metal. This is because when different metals are used, an electrochemical reaction can occur at the interface between the metal and the electrolyte, leading to polarization. By using electrodes with the same metal, the likelihood of this reaction is minimized, ensuring accurate and reliable measurements.

Needle electrodes can be placed in the trapezius muscle in order to monitor cranial nerve XI. The trapezius muscle is innervated by cranial nerve XI, also known as the accessory nerve, which controls the movement of the shoulder and neck. By placing needle electrodes in the trapezius muscle, the activity of cranial nerve XI can be monitored and assessed. This can be useful in diagnosing and evaluating conditions that affect the function of this nerve, such as nerve damage or muscle weakness.

Needle electrodes can be placed in the tongue muscles to monitor the activity of cranial nerve XII, also known as the hypoglossal nerve. This nerve controls the movement of the tongue, and by monitoring the electrical signals in the tongue muscles, the function of cranial nerve XII can be assessed.

The correct answer is Cochlear Microphonic (CM), Summating Potentials (SP), and auditory nerve compound action potentials. These are the combinations of responses that make up the Electrocochleogram (ECochG). The CM is a low-frequency response generated by the outer hair cells in the cochlea, the SP is a mid-frequency response generated by the inner hair cells and auditory nerve fibers, and the auditory nerve compound action potentials are high-frequency responses generated by the auditory nerve fibers. Together, these responses provide valuable information about the function of the cochlea and auditory nerve.

The purpose of IOM (Intraoperative Monitoring) during tethered cord surgeries is the identification and resection of filum terminale. This refers to the surgical procedure where the filum terminale, a thin thread-like structure at the end of the spinal cord, is identified and removed to relieve tension and improve symptoms associated with tethered cord syndrome. IOM helps in monitoring the neural pathways and spinal cord function during the surgery to ensure the safety and efficacy of the procedure.

Pyramidal cells are the main type of neurons found in the cerebral cortex, and they play a crucial role in generating the electrical activity measured by EEG. These cells have a pyramidal shape and are responsible for transmitting signals from one area of the cortex to another. They are known to generate both positive and negative charges, which contribute to the summation of electrical activity observed in EEG recordings. Therefore, pyramidal cells are the correct answer for the question.

Luque instrumentation consists of two flexible L-Shaped rods and sublaminar wires. This type of instrumentation is commonly used in spinal surgeries, particularly for scoliosis correction. The rods are shaped like an "L" and are flexible to allow for better contouring to the spine. The sublaminar wires are placed under the lamina of the vertebrae and are used to provide additional stability and support. This combination of rods and wires helps to correct the curvature of the spine and maintain proper alignment.

The wavelength of a wave is the distance between two corresponding points on the wave. In the case of 60Hz noise, the frequency is given as 60Hz, which means that the wave completes 60 cycles per second. To find the wavelength in milliseconds, we can use the formula: wavelength = 1/frequency. Therefore, the wavelength of 60Hz noise would be 1/60Hz = 0.0167 seconds = 16.67 milliseconds.

The correct answer is Event related potentials (ERP). P300 is a type of event related potential that is measured using electroencephalography (EEG). It is a positive wave that occurs approximately 300 milliseconds after a stimulus is presented. P300 is associated with cognitive processes such as attention, memory, and decision-making. It is often used in research and clinical settings to study cognitive function and to diagnose neurological disorders.

If we increase the stimulation from 40db to 80db, the sound pressure is increased by a factor of 2. This means that the sound pressure is doubled when the stimulation is increased by 40db.

The posterior tibial nerve is formed by the spinal roots at the level of L4-S3. This means that the nerve is derived from the spinal nerves that exit the spinal cord between the fourth lumbar vertebra and the third sacral vertebra. These spinal roots come together to form the posterior tibial nerve, which supplies sensation and motor function to the posterior compartment of the leg and the sole of the foot.

Aphasia is the correct answer because it is a condition characterized by the loss or impairment of the ability to speak or understand language. Electrical stimulation of the Broca's area, which is responsible for language production, can sometimes restore speech abilities in individuals with aphasia. Tinnitus is a condition characterized by ringing in the ears, ataxia is a lack of muscle coordination, and apraxia is a motor disorder affecting the ability to perform voluntary movements.

The P14 is generated from the caudal medial lemniscus.

The reference input of a differential amplifier is also known as both a positive input and a non-inverting input. In a differential amplifier, the reference input is compared to the other input, which is typically the signal input. The reference input is connected to the non-inverting terminal of the amplifier, which means that it does not invert the signal polarity. At the same time, the reference input is usually biased to a positive voltage level, hence it is also referred to as the positive input. Therefore, the correct answer is both.

The pudendal nerve is formed by the spinal roots at the S2-S4 level. This is because the pudendal nerve originates from the sacral plexus, which is formed by the spinal roots of the sacral segments S2-S4. These spinal roots combine to form the pudendal nerve, which supplies sensory and motor innervation to the perineum, external genitalia, and anal region.

GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter. It functions by reducing the activity of neurons and decreasing the likelihood of an action potential being generated. This inhibitory effect helps to regulate and balance brain activity. Acetylcholine and epinephrine, on the other hand, are excitatory neurotransmitters that promote the generation of action potentials and stimulate neuronal activity. Therefore, GABA is the correct answer as it is the only inhibitory neurotransmitter listed.

The epidural electrode should be placed above the dura. This is because the dura is the tough outermost layer of the spinal cord and brain, and placing the electrode above it allows for proper positioning and effective delivery of electrical stimulation. Placing the electrode below the dura or in the muscles would not target the desired area accurately, and placing it above and below the dura is not necessary as it may cause unnecessary complications.

In a patient with a hematocrit between 10-15%, there is a decrease in the concentration of red blood cells in the blood. This decrease in red blood cells can lead to a decrease in the amplitude of SSEP (somatosensory evoked potential) waveforms. Additionally, the decrease in red blood cells can also affect the conduction of nerve signals, causing an increase in the latency or delay in the SSEP waveforms. Therefore, in this scenario, the SSEP waveforms would show a decrease in amplitude and an increase in latency.

The most reliable criteria for SSEP abnormality is the presence of both absence of the obligate waveforms and prolongation of the inter-peak latencies. This means that if either of these criteria is present, it indicates an abnormality in the SSEP.

Both a bolus of propofol and a bolus of thiopental can cause burst suppression. Burst suppression refers to a pattern of electroencephalogram (EEG) activity characterized by alternating periods of high amplitude bursts and periods of electrical silence. Both propofol and thiopental are intravenous anesthetic agents that can induce burst suppression as part of their pharmacological effects on the central nervous system.

Unilaterally refers to the delivery of click stimulators on one side only. This means that the stimulators are applied to either the left or right side of the body. Bilaterally, on the other hand, would mean that the stimulators are applied to both sides simultaneously. Without further context, it is difficult to determine the specific circumstances or reasons for choosing one approach over the other.

The active input of the differential amplifier is also called both a negative input and an inverting input because it is responsible for producing an output that is the opposite polarity of the input signal. This means that when a positive voltage is applied to the active input, the output will be a negative voltage, and vice versa. Therefore, both terms accurately describe the active input of a differential amplifier.

An IOM system with 12-bit of vertical resolution means that the system has a 12-bit analog-to-digital converter (ADC). A 12-bit ADC can represent 2^12 or 4096 different data points. Therefore, the correct answer is both 4096 and 2^12.

Inhalational agents refer to the gases or volatile liquids that are used to induce and maintain anesthesia. These agents are primarily used to depress the central nervous system and produce a state of unconsciousness. While they may have some effect on the motor evoked potential (MEP), they are generally considered to have the least effect compared to other agents like neuromuscular blockers such as Rocuronium and Succinylcholine. Neuromuscular blockers specifically target the neuromuscular junction and inhibit the transmission of nerve impulses, resulting in muscle relaxation and potentially a greater impact on MEP. Therefore, inhalational agents are the least likely to affect MEP.

Increasing the stimulation intensity will decrease the latency in D-Wave. This means that the time it takes for D-Wave to respond or process information will be reduced. Higher stimulation intensity leads to a faster response time, resulting in a decrease in latency.

The interstimulus interval (ISI) refers to the time interval between two consecutive stimuli. In this question, the correct answer is 2.5 milliseconds. This means that there is a gap of 2.5 milliseconds between each stimulation when the frequency is 400Hz. This information helps in understanding the timing and spacing of the stimuli, which can be important in various fields such as psychology, neuroscience, and sensory perception studies.

Intraoperative TCD, which stands for Transcranial Doppler, is commonly used during Carotid Endartectomy surgery. This procedure involves removing plaque buildup from the carotid artery in order to improve blood flow to the brain. Intraoperative TCD is used during this surgery to monitor blood flow and detect any potential complications such as emboli or changes in cerebral blood flow. By using TCD, surgeons can ensure that the procedure is being performed successfully and that there are no adverse effects on the brain's blood supply.