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

Isoflurane causes greater cortical evoked potential suppression than desflurane or sevoflurane at equivalent MAC values due to its profound effect on cortical synaptic transmission.

Question 2

Nitrous oxide specifically affects evoked potentials by:

Accepted Answer

Reducing amplitude of cortical responses, particularly affecting MEPs significantly

Answer

Nitrous oxide, particularly when combined with volatile agents, reduces cortical response amplitudes and has a pronounced suppressive effect on MEPs even at low concentrations.

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

TIVA with propofol and remifentanil minimizes cortical and MEP suppression while avoiding NMB that would prevent muscle CMAP recording, making it the gold standard for IONM.

Question 4

How do opioids affect intraoperative evoked potentials?

Accepted Answer

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

Answer

Opioids at clinical doses have minimal effects on SSEPs, MEPs, and BAEPs, making them compatible with IONM and suitable as part of TIVA protocols for monitored cases.

Question 5

Etomidate transiently increases SSEP amplitudes because it:

Accepted Answer

Decreases synaptic inhibition in the somatosensory cortex

Answer

Etomidate decreases cortical inhibitory activity (GABA modulation), temporarily enhancing cortical excitability and increasing SSEP amplitudes, which can be exploited therapeutically.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Anesthesia Effects on Neurophysiological Monitoring