ABRET Certified Neurophysiologic Intraoperative Monitor (CNIM) Practice Exam

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• What happens if SSEP responses show significant variability during monitoring?
• What is the prevalence of temporal bone hyperostosis in the geriatric population?
• What is an advantage of bipolar stimulation over monopolar during CN VII stimulation?
• What does the process of sampling do in signal processing?
• Why should raw (unprocessed) EEG be available for review during quantitative EEG monitoring?
• In the event of a detected fall in PTN responses during surgery, what is the protocol?
• What defines the neuroforamen?
• What condition is associated with a normal curve of the lumbar spine that develops early in life?
• What type of implant does Isola spinal instrumentation use?
• What can be a problem encountered with After Discharges (AD)?
• What is the gain of an amplifier set to give an output signal of 1 V for an input of 10 mV?
• What is defined as a ground loop?
• What does aliasing refer to in signal processing?
• What is the percentage of successful surgical outcomes for tethered cord release?
• What is one of the key benefits of employing SSEP monitoring during surgeries?
• What type of forces do sublaminar wires provide to the spinal column?
• What characterizes apraxia?
• What is one function of Cotrel-Dubousset and Isola instrumentation?
• What defines a syrinx in relation to the spinal cord?
• In cases of severely elevated ICP, which modalities remain unaffected?
• What is the risk associated with compression of the brachial plexus in the lateral position?
• How does HFF reduction affect SSEP latency?
• What is the frequency setting for CN VII CMAP?
• What does soft, intermittent flutter in sEMG indicate?
• How long is the post-stimulus recording window typically for SSEP?
• What is the most important step when setting up BAERs?
• Why are most evoked potentials (EPs) considered far-field responses?
• What is the significance of pre-operative SSEP baselines?
• What is the masking level required to eliminate crossover response?
• How is motor neuron damage classified?
• What is the percentage distance of Fp1 and Fp2 from Fpz?
• In the presence of radio frequency energy, what do electrodes in the operating room resemble?
• During a carotid endarterectomy (CEA), what are the suggested EEG filter, time-base, and sensitivity settings for monitoring cortical ischemia?
• What is the minimum number of trials (sweeps) that an EP recording system should allow for averaging?
• What is the importance of monitoring during IONM?
• What is the ideal blood pressure management in a craniotomy procedure?
• What kind of potentials are produced from changes in synaptic transmission?
• What is the most likely cause of 60 Hz artifact?
• What is the goal of AV fistula surgery?
• What happens to the SNR if you average a set of signals together?
• In terms of electrical safety, what maximum current flow is typically allowed to prevent patient harm during monitoring?
• What advantage do platinum epidural electrodes have over other types?
• What physiological change does a decrease in high frequency waves indicate during intra-carotid sodium amytal injection?
• What is a common threshold for tolerance of cross-clamp baselines in surgical patients?
• What is a key feature of Texas Scottish Rite Hospital spinal instrumentation?
• In cranial nerves, where is motor nuclei typically located?
• What method can be used to enhance clarity of signals in neurophysiological monitoring?
• What classification does Succinylcholine fall under?
• Which of the following is least likely to cause electrical interference in the operating room?
• Which symptom is commonly associated with an acoustic neuroma?
• What is primarily responsible for the initial recruitment of large diameter nerve fibers during stimulation?
• What is a significant predictor of outcome when there is a 30-50% decrease in D-wave amplitude but unchanged MEPs?
• Which condition is associated with motor nerve conduction blockage without axonal damage?
• According to nursing guidelines, what is the minimum distance required from the sterile field?
• What are the unpaired cranial bones?
• Where does Meckle's Cave sit?
• What is the first step in the process of Intraoperative Neuromonitoring (IONM)?
• Which anesthetic agent is noted for being the least depressant on SSEPs?
• During a surgical procedure, if a surgeon hits the spinal cord, what is an immediate step that should be taken?
• What physiological response is typically measured by TCeMEPs and H-reflexes?
• What can median nerve SSEPs help measure?
• What must be ensured for the grounding device under normal conditions?
• When converting analog signals to digital, what process involves discretizing the signal?
• What are the potential complications of pedicle screw placement at the cervical level?
• Which anesthetic agents are most compatible with myogenic MEPs?
• Idiopathic scoliosis is present in what percentage of pediatric patients aged 10-16 years?
• How is muscle relaxation assessed during monitoring?
• In MEP stimulation, where should the anode be placed?
• What is a disadvantage of using PTN SSEPs during scoliosis surgery?
• Which cranial nerve is most commonly injured?
• Which frequency range is most commonly utilized for cortical ischemia monitoring in EEG?
• What effect does high-dose maintenance of Fentanyl have on EEG?
• What does the CCT for median nerve SSEP refer to?
• What is the purpose of using low doses of Etomidate, Ketamine, or Methohexital?
• What phenomenon can cause random spike discharges during CN VII dissection?
• Why is glucose monitored and treated during surgery?
• According to the Nyquist Frequency, what is the sampling rate required for an analysis?
• What does Hoffman’s Reflex involve?
• Harrington rod instrumentation utilizes which type of implants?
• M-waves are more effectively stimulated by which type of stimulation?
• What is the minimum vertebral level below which D-waves cannot be recorded?
• Which statement is true regarding the effect of ketamine on SSEPs and MEPs?
• What does neurapraxia refer to?
• What device is used in robotic da Vinci thyroidectomy to simultaneously dissect and cauterize?
• What is the typical sensitivity setting recommended for EEG during CEA?
• What phenomenon occurs when metal touches metal in relation to sEMG responses?
• What type of responses should surgical staff look for when a patient is asleep during mapping?
• What must the amplifier input impedance of a differential amplifier be at a minimum?
• Where are BAER waves III-V generated?
• What is a common artifact source in a subcortical channel that can be resolved using a specific technique?
• What is one advantage of direct CN VIII recordings?
• Are pre-positional recordings valid as baselines for the surgical monitoring case?
• What is the maximum time to expect EEG changes following carotid cross-clamping?
• What type of hearing loss is presbycusis primarily associated with?
• What could potentially cause a false negative during a T10 surgery?
• Which cranial bone is paired among the cranial bones?
• A BAER latency increase of 0.9 ms for both left and right wave V in a 10 minute period most likely indicates what?
• During which type of surgery is the anterior vasculature of the spine at greatest risk?
• To accurately represent the amplitude of an EP waveform, what must be matched?
• What EEG change is expected following the intra-carotid injection of sodium amytal?
• To avoid ground loops, how should the patient be grounded?
• Upon transfer from surgery to the epilepsy monitoring unit, what is one of the potential outcomes that can occur?
• What is the recommended secure method for applying surface cup electrodes?
• What percentage of the brainstem area do BAERs and SSEPs monitor?
• What type of response is primarily evaluated when monitoring PTN during spinal surgery?
• Within what time frame do 80% of clamp-related EEG changes during CEA occur?
• What is the purpose of the amplifier box ground?
• Distraction on the spinal cord using Harrington rod instrumentation cannot be tested by which modality?
• What does the term "cortical ischemia" refer to in the context of CEA monitoring?
• What is the point that is 20% anterior to Cz?
• What characteristic differentiates large diameter nerve fibers from small diameter fibers?
• What is the significance of increased latencies observed during BAER testing?
• Which of the following is used to measure residual "stump" pressure during CEA?
• Which muscle groups are most appropriately monitored for L5 and S1 nerve roots in sEMG?
• What is the primary blood supply for the spinal cord?
• Which muscles are typically targeted for sEMG monitoring of the Trigeminal nerve?
• What is the expected post-operative motor outcome for a T7 tumor resection with complete loss of upper extremity responses and intact lower extremity responses?
• What is the purpose of placing an Ivalon/Teflon pad in MVD procedures?
• When electrocautery affects EP waveforms, what should be continued to monitor the signals?
• Which aspect of an amplifier directly influences the size of the output current based on a small input current?
• What condition is indicated by thrombosis and embolism in relation to vascular complications?
• What does the term 'glia' originate from?
• What is the name of the firm outer layer of the intervertebral disc?
• What indicates adequate stimulation of the median nerve during IONM?
• What is the sensitivity setting on an amplifier set to produce a vertical deflection of 1 cm with an input of 10 mV?
• What is the frequency range for Delta EEG waves?
• What is a notable characteristic of Nitrous Oxide as an anesthetic agent?
• What is phenytoin (Dilantin) primarily used for?
• What happens to the spinal cord at the level of the conus medullaris?
• What must be done to electrode lead wires in the operating room?
• Which anesthetic agent has the fastest elimination rate from the body?
• Why might visual observations of facial muscles during CN VII stimulation be misleading?
• At what frequency does an increase in latency and decrease in amplitude occur for BAER?
• In what area of the nervous system would you find wave IV of BAER?
• What forms the basis for artifact rejection in neurophysiologic monitoring?
• What does a decrease in the power of Spectral Edge indicate?
• What is the primary risk to the spinal cord during Luque instrumentation?
• What can cause quadraparesis in a sitting position due to neck flexion?
• Where should the ground electrode be placed for peroneal nerve SSEP stimulation?
• When preparing a patient for IONM, how should wires be positioned?
• In which scenario can BAER waveforms not be recorded?
• What is the function of collodion in electrode application?
• What pulse width (PW) is known to excite more motor fibers than sensory fibers?
• What can alter structural functional anatomy in the nervous system?
• What device is primarily responsible for transforming small input signals to larger output signals in monitoring equipment?
• What type of stimulator is typically used for anatomical nerve mapping?
• At what rate does the average person shed skin cells?
• Why is a low-frequency filter (LFF) setting of 100 Hz preferred for recording spinal cord evoked potentials (SC EPs)?
• Which factor is least likely to affect the neurogenic response to spinal cord stimulation?
• In what scenario would you expect accelerated firing in sEMG patterns?
• What is the mechanism of action of TIVA in affecting patient movement?
• How does hydrostatic pressure depend on body position?
• How often should EP machines be calibrated and safely tested?
• If a patient experiences decreased PTN responses, what is the best initial step?
• What type of activity does Frontal Intermittent Rhythmic Delta Activity (FIRDA) respond to?
• Which surgical approach sacrifices hearing during the dissection for vestibular schwannoma?
• What does the presence of muscle activity in the response during sEMG monitoring indicate?
• What is the primary characteristic of EEG activity during anesthesia?
• Which of the following tests is least likely to be affected by elevated intracranial pressure?
• When patient cooperation is insufficient during mapping, what alternative approach can be taken?
• What type of activity does cardiac monitoring on the CSA/CDSA primarily display?
• What determines the integrity of CN VII during acoustic neuroma surgery?
• What is the likely physiological cause when SSEPs and MEPs are lost after the surgeon slips and hits the spinal cord, but responses return after a few minutes?
• What changes in SSEP would occur during a positioning effect of the left arm?
• What aspect of large diameter nerve fibers makes them vulnerable?
• In which situations do most strokes associated with CEA occur?
• What measurement units are used in the International 10-20 system?
• What is a key characteristic of electrodes when exposed to radio frequency energy?
• What can excessive neck flexion in a sitting position lead to?
• How many discrete voltage values does a 10-bit A/D converter have in its range?
• What auditory wave is typically the last to occur during BAER testing?
• To stimulate both PTN asynchronously, what is required?
• How is the gain of a differential amplifier defined?
• What is the characteristic effect of barbiturates on an EEG?
• What is the purpose of Fast Fourier Transformation (FFT) in EEG analysis?
• What should be done if subcortical responses remain stable while cortical responses decrease?
• What is a defining feature of micro-embolic signals in TCD?
• What type of fibers are present in cranial nerves?
• What should be done for a patient with conductive hearing loss in relation to BAER stimulation?
• What is the risk of using toxic metals in epidural electrodes?
• Why do stimulators used for direct nerve stimulation have Teflon coating at the tip?
• Which of the following is typically a consequence of central cord syndrome?
• Which anesthetic enhances the effect of neuromuscular blockers at the neuromuscular junction?
• What is suggested by the presence of sEMG trains?
• In which areas is the sterile table with instruments and implants considered sterile?
• What is the minimum common-mode rejection ratio (CMRR) for amplifiers used in EP recording?
• Can boiling water be effectively used to sterilize surgical instruments?
• What is a potential effect of structural changes in the nervous system?
• In a bipolar EEG montage, what signifies a localizing sign?
• Which of the following describes a condition occurring during After Discharges (AD)?
• What frequency is commonly used for TCD transducers?
• If you receive a shock from the chassis of your machine during monitoring, what is the first step you should take?
• When aiming to optimize stimulation, what is likely to help with reducing discomfort during nerve monitoring?
• How many pairs of cranial nerves are there?
• What is the resulting sweep when a 100 ms epoch is recorded with a 10 ms post-stimulus triggering?
• How far is C3 located from the left pre-auricular point?
• What is the effect of AICA vasospasm on BAER?
• At what age does the normal curve of the lumbar spine take place?
• What indicates significant changes in cervical and cortical SSEPs during IONM?
• At what temperature is it most likely for EEG activity to disappear?
• Where do the cranial nerves emerge from?
• What is the term for the (+) input of a differential amplifier?
• Which of the following is a characteristic of dexmedetomidine (Precedex)?
• What does TOF refer to in the context of PTN stimulation?
• What is a significant advantage of using grid or strip electrodes over the "crown of thorns" in ECoG monitoring?
• What is the main purpose of monitoring raw data during IONM when EP waveforms are disrupted?
• When assessing evoked potentials, what is crucial for accurate readings?
• Compression fractures typically result in which type of injuries?
• Why is high input impedance important for a differential amplifier?
• What effect may Isoflurane 1.7% induce during neurophysiologic monitoring?
• In the context of neurophysiologic monitoring, what does a higher amplitude waveform indicate?
• During a robotic da Vinci thyroidectomy, what is the optimal arm angle for the patient?
• What is the most common cause of neurological deficit as a complication of spinal surgery?
• What is the period of a 200 Hz signal?
• What is most likely to be produced by movement artifact in EEG monitoring?
• If a patient’s threshold is 25 dB and the stimulator is set to 85 dB, what is the intensity in dB SL?
• What is the primary goal of microvascular decompression (MVD)?
• What is the effect of Etomidate on MEPs and SSEPs?
• What does the Spectral Edge represent in EEG analysis?
• Which brain structure corresponds to the generation of wave III of BAER?
• Which electrode application material is not permitted for use in the operating room?
• What does the sound stimulus intensity at the tympanic membrane depend on?
• Which of the following best describes a burst fracture mechanism?
• What is the purpose of taking baselines in IONM?
• What type of surgical technique is primarily avoided in translabyrinthine approaches?
• Why are pre-operative SSEP baseline values essential in intraoperative neuromonitoring (IONM)?
• In TCD monitoring, what is the primary quantitative value measured?
• What characteristic is true regarding short-latency SSEP responses compared to longer latency responses?
• What abnormality in latency may be seen with vascular malformations in the posterior fossa?
• What area does the middle cerebral artery primarily supply in the cerebral cortex?
• What is a significant consequence of unstable blood pressure effects on cortical SSEPs?
• What is the stim intensity for activating a sensory nerve in the OR?
• MAC is most accurately approximated by the effect of anesthesia on which reflex?
• What is the most common source of patient infection in the operating room?
• Which of the following is NOT a potential complication associated with lumbar pedicle screw placement?
• What type of gait issues may a patient with an acoustic neuroma experience?
• What is the primary purpose of recording spinal potentials?
• If no MEP responses are detected for 15-20 minutes after induction, which muscle relaxant was likely used?
• Which area of the spine is characterized by small pedicles, long spinous processes, and large inter-vertebral foramina?
• In the context of IONM, why is documenting findings essential?
• What is the effect of nitroprusside on blood pressure during surgery?
• Which anesthetic agent is particularly desirable for pediatric patients during TCeMEP monitoring?
• What characterizes a burst fracture?
• What is a consequence of increased venous pressure in the body?
• During a pre-op study, what can be done to reduce a patient's discomfort at the wrist while maintaining adequate stimulation?
• Which feature is commonly referred to as the chin bone?
• What is the optimal BIS range for anesthesia?
• What does the stimulation of the apex of the cochlea primarily relate to?
• Where can P31 responses to PTN stimulation be recorded?
• In a case of sudden loss of SSEPs and MEPs during surgery, what does it indicate about the condition of the spinal cord?
• Why is it important to prep the skin before electrode application?
• What type of drug is Ketamine categorized as?
• If the SNR is 1:2, averaging 64 responses will improve the ratio to what?
• At which vertebral level does the spinal cord typically end?
• Which anesthetic agents do not act on the same neuronal receptors?
• What is the primary reason platinum is used in epidural electrodes?
• What contraindications exist for TCeMEP?
• What does distraction refer to in a surgical context?
• What effect do opioids have on myogenic MEPs?
• What is the required horizontal resolution of an EP system?
• What is the key element of any amplifier in terms of converting current?
• Which condition could negatively affect the amplitude and latency of BAER recordings?
• What effect do surface electrodes have on compound muscle action potential (CMAP) amplitude?
• Which SSEP component would be most affected by a tumor in the spinal cord/medulla intersection?
• Which of the following steps is NOT part of the IONM process?
• In SSEP monitoring, why is it critical to maintain appropriate filter settings?
• What is an appropriate filter range for a short-latency SSEP cortical response?
• Where is the most productive electrode placement for an ECochG?
• What is one effective way to reduce EKG-related artifact during monitoring?
• Which EEG wave frequency is associated with alert and active states?
• What is the acceptable stimulation rate range for BAER?
• What is essential for minimizing artificial amplitude asymmetries when using subdermal needle electrodes?
• If a system has a sampling rate of 10 kHz, what is the shortest sine wave that can be resolved?
• Which of the following is an advantage of general anesthesia during carotid endarterectomy (CEA)?
• What type of electrode is considered sensitive during CN VII recordings?
• What is the sensitivity of peripheral nerves to injury compared to spinal cord grey matter?
• Latency changes are primarily caused by effects on which type of receptors?
• What is the main source of airborne bacteria in the operating room?
• What is the main action of propofol concerning EEG readings?
• How does Nitrous Oxide impact Intraoperative Neurophysiologic Monitoring (IONM) when mixed with Isoflurane?
• Which frequency range is categorized as Theta waves?
• What could a positive Babinski sign indicate?
• How do filter settings differ between cortical and peripheral responses in SSEPs?
• Why does poor ground resistance pose a safety risk?
• What might happen to cortical peaks when lowering the high-frequency filter (HFF) from 500 Hz to 200 Hz?
• What is the effect of changing the HFF during a critical moment in SSEP monitoring?
• Why is it important to have matching impedances in neurophysiologic monitoring?
• What is the maximum leakage current allowed through each patient lead in the operating room equipment?
• What type of muscle relaxant is Rocuronium classified as?
• If motor twitch cannot be evaluated, what should be done?
• Why must subdermal needle electrodes be inserted symmetrically over homologous brain areas?
• What kind of sEMG response is characterized by enhanced activity in the presence of compression?
• Which facial muscle is not monitored for CN VII sEMG?
• Which anesthetic has effects consistent with actions at the level of the cortex?
• During a neurological procedure, which of the following would be a critical factor in monitoring?
• What is a common source of air embolism introduction into the blood supply?
• When recording SSEP responses in an awake patient, what is the motor threshold?
• What is a key aspect of monitoring patients in the epilepsy unit after surgical procedures?
• On an equi-MAC basis, which anesthetic has the greatest effect on the Motor Evoked Potentials (MEPs) of recorded muscles?
• Which inhalation agent is known to prominently suppress myogenic MEPs?
• If a pedicle screw tests above the accepted threshold, what should you do?
• Which of the following is NOT a type of spinal instrumentation?
• What is the effect of inhalation agents on I-wave numbers?
• Which gender is more likely to experience progression of scoliosis in pediatric patients?
• What is Lhermittes Sign?
• Given a differential amplifier with a gain of 1,000,000 and inputs of 0.2 uV and 0.8 uV, what is the output?
• In SSEP, which electrode is closest to the post-central gyrus?
• What is the minimum bandpass required for an evoked potential system?
• Where should an electrode be placed to record the compound action potential (AP) of the MN intra-operatively?
• What effect does Propofol have on the latencies of BAERs?
• If PTN cortical responses attenuate over three hours while subcortical responses remain stable, what action should be taken?
• A semi-critical infectious device requires what type of disinfection after each use?
• What should be monitored closely in the context of intraoperative BAERs to ensure stable results?
• What predicts transient motor deficits during intramedullary spinal cord tumor resection?
• True or False: A 50% drop from pre-cross-clamp baselines indicates hypoperfusion.
• Which statement is true regarding the action of different anesthetic agents?
• What do universal precautions involve in the context of patient care?
• Where should SSEP stimulation electrodes not be placed?
• Which of the following is NOT a major mechanism of action for common anesthetic agents affecting IONM?
• What is a possible effect of high/low glucose levels during surgery?
• Which method should be avoided when placing PTN stimulators?
• In monopolar CN VII stimulation, which way does the charge flow?
• What are cavernous angiomas characterized by?
• Which consideration is least important during intraoperative BAERs?
• What is the optimal stimulation rate for BAER?
• Which settings are typical for brainstem tEMG?
• What is the primary advantage of using intraoperative monitoring (IM) electrodes compared to surface electrodes?
• SC stimulation is used to monitor what during surgical procedures?
• Which of the following terms describes the cavities inside the skull?
• What are the characteristics of Central Cord Syndrome (CCS)?
• What does a continuous, non-accelerating tapping pattern in sEMG signify?
• What is a common effect of high thresholds in areas with structural damage during monitoring?
• What is the maximum allowable chassis leakage current in an operating room setup?
• What is the primary purpose of isolated amplifier inputs in neurophysiologic monitoring?
• What is the key factor in confirming a loss of response is not artifact but a real change?
• If your initial signal amplitude is 0.5 uV inside a background noise level of 2 uV, what will the signal-to-noise ratio (SNR) be after 400 averages?
• What condition is characterized by high frequency hearing loss that gradually occurs in older individuals?
• Low frequency sounds are perceived at which part of the cochlea?
• What is the primary focus of pre-stimulus triggering in SSEP?
• What is quantization error in the context of A/D conversion?
• According to the International 10-20 system, which landmark is the most challenging to locate?
• What is the frequency of a signal if the interval between each cycle of the signal is 0.3 ms in a 30 ms sweep?
• How many averages are needed to achieve a 2:1 SNR if the signal amplitude is 5 uV and the noise amplitude is 20 uV?
• Which noise reduction technique is most effective at reducing EKG artifact?
• Which time constant is more effective for cutting out low frequency noise from a signal?
• During a thoracic laminectomy, what should be the first response to rapid loss of right PTN cortical responses?
• What characteristic is typical of normal TCD waveforms?
• What is the primary focus of surgical distraction?
• Which aspect of the spinal cord's blood supply is true?
• In the lateral position, besides compression of the brachial plexus, which major nerve is at risk?
• Which device typically produces electrical interference due to the cycling of electric alternating current?
• What shared characteristics do TCeMEPs and H-reflexes exhibit?
• How much does the latency of BAER wave V increase for each degree Celsius drop in temperature?
• What is the role of current-limiting in EP equipment leads?
• What should be monitored closely if stimulus delivery is initiated during mapping?
• Why is skin/scalp prep necessary before applying surface electrodes?
• What effect does Fentanyl generally have on SSEPs?
• What is stimulated by the posterior tibial nerve (PTN) contractions?
• What are two potential vascular complications related to CEA?
• What is the primary advantage of using Dural- or Direct-SSEP SC recordings?
• What should be the best recommendation when SSEPs and MEPs are lost after a surgical incident?
• To protect the patient from electrical shock, how much current flow is limited to by the circuitry in an isolated input board?
• How do most sources of electrical artifact emit noise into the air?
• What is the maximum time a patient without collateral blood supply can tolerate during a carotid endarterectomy before post-operative deficits occur?
• In a C5s-Fpz montage with lower extremity stimulation, the expected response is generated at which location?
• What is the primary outcome of prolonged hypoxia related to increased venous pressure?
• When it comes to Etomidate, which statement is accurate?
• What area of the body is typically targeted and stimulated to observe motor responses during intraoperative neurophysiologic monitoring?
• What type of sEMG pattern is indicative of permanent injury?
• What are the methods used to monitor brain perfusion during CEA?
• Which factor is crucial in determining effective SSEP response recording?
• What is a key differentiator between an sEMG train and a burst?
• How does propofol primarily influence somatosensory evoked potentials (SSEPs)?
• What are the first three waveform components at the onset of Brainstem Auditory Evoked Responses (BAERs)?
• Which aspect can complicate monitoring efficacy during scoliosis surgery?
• What potential risk is associated with seizures occurring during mapping?
• What vascular condition is associated with BAER latency abnormalities in the posterior fossa?
• What indicates a failure in normal wave generation in BAER testing?
• What is a consequence of using a notch filter in SSEP recordings?
• What is the most effective way to stimulate the motor pathway with minimal movement in the surgical field?
• What is a common consequence of thoracic pedicle screw placement?
• Which electrophysiological modality is most affected by propofol?
• What is the initial waveform recorded of a near-field potential?