ABRET CNIM Neurophysiologic Intraoperative Monitoring

During a spinal fusion surgery, the surgeon requests monitoring of somatosensory evoked potentials (SSEPs). Which neural pathway do SSEPs primarily assess?

• ACorticospinal tract (lateral column)
• BDorsal column-medial lemniscal pathway
• CSpinothalamic tract
• DAnterior corticospinal tract

A CNIM technologist is reviewing a patient's medical history before a thyroidectomy. The surgeon plans to monitor the recurrent laryngeal nerve. Which cranial nerve is being monitored?

• ACranial nerve IX (glossopharyngeal)
• BCranial nerve X (vagus)
• CCranial nerve XI (spinal accessory)
• DCranial nerve XII (hypoglossal)

During posterior fossa surgery, brainstem auditory evoked potentials (BAEPs) are monitored. Wave V of the BAEP originates from which anatomical structure?

• ACochlear nerve (CN VIII)
• BCochlear nucleus
• CSuperior olivary complex
• DLateral lemniscus/inferior colliculus

Which statement best reflects current practice when evaluating a possible intraoperative SSEP alert?

• AAny visible change is automatically a surgical injury
• BOne universal numeric threshold applies to every patient and modality
• CTraditional 50% amplitude and 10% latency changes are useful reference points, but reprod…
• DOnly latency matters; amplitude and waveform quality can be ignored

During scoliosis correction, SSEPs are suddenly lost bilaterally. What is the most appropriate immediate response?

• AAnnounce the change promptly and coordinate parallel checks of the stimulus and recording…
• BAssume an anesthetic bolus is the cause before checking the monitoring system or physiolo…
• CWait for unilateral loss because bilateral loss cannot reflect a surgical or positioning…
• DContinue collecting data silently until the end of the case

Which anesthetic agent has the LEAST suppressive effect on motor evoked potentials (MEPs)?

• AIsoflurane
• BSevoflurane
• CPropofol (TIVA)
• DNitrous oxide

During carotid endarterectomy (CEA) monitoring, EEG shows unilateral attenuation of faster frequencies and increase in slow-wave activity (delta) ipsilateral to the clamped carotid artery. This finding indicates:

• ANormal EEG change under general anesthesia
• BCerebral ischemia in the territory of the clamped carotid
• CTechnical artifact from the surgical field
• DContralateral hemispheric dysfunction

What is the primary purpose of free-running electromyography (EMG) during intraoperative monitoring?

• ATo measure nerve conduction velocity
• BTo detect spontaneous mechanical or thermal irritation of motor nerves
• CTo assess the integrity of sensory nerve pathways
• DTo quantify the depth of neuromuscular blockade

A technologist is setting up for monitoring during an acoustic neuroma (vestibular schwannoma) resection. Which modalities should be included in the monitoring plan?

• ASSEPs and MEPs only
• BBAEPs, facial nerve EMG (CN VII), and possibly CN V monitoring
• CEEG only
• DSSEPs and free-running EMG of the extremities

During transcranial motor evoked potential (TcMEP) monitoring, the technologist uses a multipulse stimulation technique. The typical number of stimuli in a train and the interstimulus interval are:

• A1 stimulus at 500 Hz
• B3-7 stimuli at 2-4 ms interstimulus intervals (250-500 Hz)
• C20-50 stimuli at 10 ms intervals
• D100 stimuli at 1 ms intervals

Which electrode montage is standard for recording upper extremity SSEPs from median nerve stimulation?

• ACz'-Fz (cortical), C5s-Fz (subcortical), Erb's point (peripheral)
• BC3'-C4' only
• CFpz-Oz for all recordings
• DO1-O2 (occipital)

A patient undergoing spinal surgery has a pre-existing peripheral neuropathy documented in their medical history. How should this affect the IONM monitoring plan?

• APeripheral neuropathy has no effect on IONM recordings
• BCancel all monitoring because reliable baselines cannot be obtained
• CExpect potentially prolonged latencies and reduced amplitudes in baseline recordings; adj…
• DOnly monitor MEPs because SSEPs are unreliable in neuropathy

During pedicle screw placement in the lumbar spine, triggered EMG is used to assess screw placement accuracy. A stimulation threshold of 6 mA produces a compound muscle action potential (CMAP) response. This finding suggests:

• AThe screw has breached the pedicle wall and is in direct contact with a nerve root
• BThe screw is properly positioned within the pedicle with intact cortical bone
• CThe screw is too long and compressing the spinal cord
• DThe stimulation intensity is too low to be clinically meaningful

Which of the following best describes a neurotonic discharge pattern on free-running EMG?

• ARegular, rhythmic motor unit firing at a constant rate
• BIrregular, high-frequency burst activity with varying morphology, indicating mechanical n…
• CLow-amplitude, high-frequency interference pattern from voluntary muscle contraction
• DPeriodic sharp waves occurring at regular intervals

A technologist notices high electrode impedance (>5 kΩ) on several recording channels during setup. The most appropriate corrective action is to:

• AProceed with monitoring and compensate by increasing amplifier gain
• BReapply the electrodes after cleaning the skin with abrasive prep gel to reduce impedance
• CSwitch to a bipolar recording montage
• DReduce the low-frequency filter setting

Which approach best localizes an intraoperative SSEP change before it is attributed to one anatomic level?

• ACompare reproducible peripheral, subcortical, and cortical responses while checking techn…
• BUse the cortical channel alone because upstream recordings add no localization value
• CAssume every bilateral change localizes to the cervical spinal cord
• DIgnore acquisition changes once a baseline has been saved

What is the primary safety concern when performing transcranial electrical motor evoked potentials (TcMEPs)?

• ARisk of hearing loss from stimulation artifact
• BRisk of patient movement causing surgical injury, tongue laceration, or dislodging of air…
• CRisk of inducing cardiac arrhythmia
• DRisk of permanent brain damage from electrical stimulation

A 60 Hz artifact is contaminating SSEP recordings. Which of the following is the MOST effective method to eliminate this artifact?

• AIncrease the number of stimulus averages
• BApply a 60 Hz notch filter
• CIdentify and correct the source of electrical interference
• DIncrease the stimulation rate to exactly 60 Hz

During monitoring of a spinal cord tumor resection, D-waves are recorded from an epidural electrode. The D-wave amplitude decreases by 60% from baseline. The clinical significance of this finding is:

• ANo clinical significance—D-waves are unreliable for spinal cord monitoring
• BA ≥50% D-wave amplitude decrease is associated with significant risk of postoperative mot…
• CD-wave changes only become significant when amplitude is completely lost
• DThis is a normal finding during intradural tumor resection

The train-of-four (TOF) test is used in IONM to assess:

• AThe depth of anesthesia
• BThe level of neuromuscular blockade
• CMotor cortex excitability
• DSensory nerve conduction velocity

Which of the following is a contraindication to transcranial electrical stimulation for MEP monitoring?

• AHistory of controlled epilepsy
• BPresence of a cochlear implant
• CPatient age over 70 years
• DMetallic skull plate or craniotomy defect directly under the stimulating electrode

When monitoring facial nerve (CN VII) function during parotid gland surgery, electrodes should be placed in which muscles?

• ATemporalis and masseter
• BOrbicularis oculi and orbicularis oris
• CSternocleidomastoid and trapezius
• DTongue and soft palate

During an aortic aneurysm repair, the surgeon asks about the current status of spinal cord monitoring. The SSEP and MEP baselines were obtained before aortic cross-clamping. After clamping, lower extremity MEPs are lost bilaterally while upper extremity MEPs and all SSEPs remain stable. This finding most likely indicates:

• ATechnical failure of the lower extremity recording electrodes
• BSpinal cord ischemia in the anterior cord from interrupted segmental artery blood flow
• CSystemic hypotension affecting all neural pathways equally
• DExcessive anesthetic depth