Anesthesia Effects on Neurophysiological Monitoring Flashcards

Dexmedetomidine's effect on intraoperative SSEP and MEP monitoring is best described as:

Answer: Mild to moderate amplitude reduction with relative preservation at typical clinical doses

Dexmedetomidine causes mild to moderate, dose-dependent reductions in SSEP and MEP amplitudes at typical clinical infusion rates but is generally compatible with intraoperative monitoring.

A sudden uniform decrease in SSEP and MEP amplitudes occurs during a propofol bolus. The most appropriate neurophysiologist action is:

Answer: Note the timing of the bolus, communicate with the anesthesiologist, and wait for stabilization

Anesthetic bolus-related changes are transient; communicating with the anesthesiologist and documenting the timing prevents false positive surgical alarms and allows appropriate interpretation.

The effect of increasing volatile anesthetic from 0.5 MAC to 1.5 MAC on SSEP cortical responses is:

Answer: Amplitude decrease and latency prolongation in a dose-dependent manner

Volatile anesthetic agents cause dose-dependent SSEP amplitude decreases and latency prolongation, with the cortical N20/P37 responses being most sensitive to MAC increases.

When SSEP baselines cannot be established after induction due to poor signal quality, the FIRST troubleshooting step should be:

Answer: Check electrode impedances, stimulator connections, and patient positioning

Technical factors (high impedance, poor electrode contact, stimulator disconnection, positioning artifacts) are the most common causes of absent baselines and should be systematically excluded first.

Why should anesthetic changes be communicated to the neurophysiologist in real-time during surgery?

Answer: So the neurophysiologist can correlate anesthetic-induced changes with evoked potential waveforms and avoid false alarms

Real-time communication of anesthetic changes allows the neurophysiologist to distinguish drug-induced signal changes from surgically induced neural injury, preventing false positive alarms.

Mean arterial pressure (MAP) below what threshold is considered physiologically significant for intraoperative SSEP monitoring?

Answer: Below 60 mmHg

MAP below 60 mmHg is generally considered the threshold below which cerebral and spinal cord perfusion may be compromised, causing ischemia-related SSEP amplitude decreases.