CNIM flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Corticospinal decussation

Most corticospinal fibers cross in the caudal medulla at the pyramidal decussation and descend as the lateral corticospinal tract, synapsing on contralateral spinal motor neurons.

Wave V generator

BAEP wave V is generated mainly by the inferior colliculus and lateral lemniscus; it is the most robust wave and is used to monitor auditory pathway integrity.

Alpha frequency band

Alpha is the 8-13 Hz EEG rhythm, usually prominent over posterior head regions during relaxed wakefulness with eyes closed, and it attenuates with eye opening.

Common-mode rejection

A differential amplifier amplifies the voltage difference between two inputs and rejects signals common to both, such as 60 Hz noise; higher CMRR means better rejection.

Ohm's law

V = I × R describes the relationship among voltage, current, and resistance; in monitoring, high electrode impedance increases noise and reduces signal fidelity.

Dorsal column pathway

The dorsal columns carry vibration and proprioception via fasciculus gracilis and cuneatus to the nucleus gracilis/cuneatus, then medial lemniscus to VPL thalamus and cortex.

EEG delta band

Delta is EEG activity below 4 Hz; it is normal in deep sleep and can appear with anesthesia, encephalopathy, or focal structural lesions.

Volatile anesthetic effect

Volatile anesthetics cause dose-dependent reduction in cortical SSEP amplitude and latency prolongation; BAEPs are relatively resistant, while MEPs are more suppressed.

Propofol and MEP

Propofol produces dose-dependent EEG slowing and burst suppression and suppresses MEPs; when MEPs are required, anesthesia depth and infusion stability must be coordinated.

Neuromuscular blockade monitoring

Neuromuscular blockade abolishes MEP and EMG signals but does not directly block SSEP or BAEP; quantitative TOF monitoring guides safe and stable dosing.

Nitrous oxide monitoring effect

Nitrous oxide, especially above 50%, can reduce MEP and cortical SSEP amplitude; it is often reduced or discontinued when robust MEP monitoring is needed.

Ketamine EEG effect

Ketamine increases fast EEG activity and can preserve or enhance MEP amplitude; it may be used as an anesthetic adjunct during motor monitoring.

Hypothermia evoked potentials

Hypothermia prolongs evoked potential latencies and reduces amplitudes; core temperature should be measured and documented because changes can mimic neural injury.

Median nerve SSEP

Median nerve SSEP uses wrist stimulation at supramaximal intensity, 0.2 ms duration, and 3-5 Hz, recording from Erb's point, cervical spine, and contralateral scalp.

Transcranial MEP train

Transcranial electrical MEP uses a train of 5-7 pulses, 50-500 µs duration, and 1-4 ms interpulse intervals to activate corticospinal pathways and record muscle CMAPs.

BAEP click rate

BAEPs use 80-100 dB nHL clicks at 10-20 Hz, a 10 ms window, and 1000-2000 averages; waves I-V assess the auditory pathway.

Pedicle screw threshold

Triggered EMG during pedicle screw stimulation: thresholds below about 6 mA raise concern for breach, while thresholds above 10-12 mA are generally reassuring.

Neurotonic EMG

Neurotonic EMG consists of high-frequency bursts or trains from mechanical nerve irritation; sustained trains are more concerning than brief bursts and warrant surgical correlation.

Phase reversal mapping

With a coronal recording array across the central sulcus, the median nerve SSEP N20/P20 dipole reverses polarity; this identifies the sensorimotor boundary during mapping.

Burst suppression

Burst suppression is an EEG pattern of high-voltage bursts separated by isoelectric periods, often from deep propofol anesthesia; cortical SSEPs and MEPs may be lost.

Electrode impedance target

Recording electrode impedance should generally be below 5 kΩ; high or unequal impedance increases noise, degrades common-mode rejection, and can mimic signal loss.

60 Hz artifact

60 Hz artifact appears as continuous sinusoidal interference; check ground and reference, electrode contact, and nearby equipment before using a notch filter that may mask real signal.

Loss of SSEP checklist

For sudden SSEP loss, check stimulation, connections, impedance, anesthesia, blood pressure, temperature, and surgical events, and notify the team promptly.

Cephalic reference

A cephalic reference is placed on the scalp or ear and used in referential montages; reference choice affects waveform morphology and must remain consistent across recordings.

Electrocautery artifact

Electrocautery produces broadband electrical artifact that obscures evoked potentials and EMG; acquisition should be paused and not interpreted during cautery.

Blood pressure and SSEP

Cortical SSEP amplitude can decline with significant hypotension; maintaining adequate mean arterial pressure and documenting blood pressure at the time of change are essential.

Critical change documentation

Document the time, modality, direction and magnitude of change, suspected cause, interventions, and the persons notified, including their response.

Closed-loop communication

Closed-loop communication requires the sender to state a message, the receiver to repeat it back, and the sender to confirm accuracy before action.

PHI minimum necessary

Protected health information should be shared only as needed for patient care; use the minimum necessary information and follow institutional privacy policies.

Baseline documentation

Baseline recordings should document modality, stimulation and recording parameters, montage, limb side, anesthetic regimen, temperature, blood pressure, and signal reproducibility.

Chain of command

When a concern is not resolved, escalate through the defined chain of command and document each notification, response, and subsequent action.

Laterality verification

Verify patient identity, procedure, and limb side before stimulation; compare left and right and document laterality to prevent wrong-side interpretation.