CNIM Anesthesia Effects on Neurophysiological Monitoring

Question 1

Which inhaled anesthetic causes the GREATEST suppression of cortical evoked potentials at equivalent concentrations?

Accepted Answer

Isoflurane

Answer

Nitrous oxide alone

Answer

Desflurane

Answer

Sevoflurane

Question 2

Nitrous oxide specifically affects evoked potentials by:

Accepted Answer

Reducing amplitude of cortical responses, particularly affecting MEPs significantly

Answer

Selectively suppressing subcortical potentials while sparing cortical ones

Answer

Having no effect on any evoked potential modality

Answer

Selectively abolishing BAEPs

Question 3

The optimal anesthetic protocol for intraoperative neurophysiological monitoring (IONM) when MEP monitoring is required is:

Accepted Answer

Total intravenous anesthesia (TIVA) with propofol and remifentanil, avoiding NMB

Answer

High-dose volatile agent with neuromuscular blockade

Answer

Ketamine infusion with 70% nitrous oxide

Answer

Halothane at 0.5 MAC with pancuronium

Question 4

How do opioids affect intraoperative evoked potentials?

Accepted Answer

They have minimal effect on SSEPs, MEPs, and BAEPs at clinical doses

Answer

They cause profound suppression of all evoked potential modalities

Answer

They selectively abolish MEPs

Answer

They increase SSEP latencies by more than 10 ms

Question 5

Etomidate transiently increases SSEP amplitudes because it:

Accepted Answer

Decreases synaptic inhibition in the somatosensory cortex

Answer

Blocks GABA receptors in the spinal cord

Answer

Activates glutamate receptors

Answer

Increases cerebral blood flow

Question 6

Ketamine's effect on intraoperative MEP monitoring is characterized by:

Accepted Answer

Relative MEP preservation or enhancement due to NMDA receptor antagonism

Answer

Severe MEP suppression requiring dose reduction

Answer

Complete abolition of corticospinal responses

Answer

Selective enhancement of BAEPs only