CNIM Motor Evoked Potentials (MEP) 3

Question 1

What does a preserved D-wave with loss of muscle MEPs during spinal cord surgery suggest?

Accepted Answer

Temporary or partial motor dysfunction with likely recovery

Answer

A preserved D-wave with MEP loss indicates the corticospinal axons are intact but spinal cord interneurons or anterior horn cells are temporarily affected, predicting functional recovery.

Question 2

How does patient body temperature affect tcMEP amplitudes intraoperatively?

Accepted Answer

Hypothermia suppresses MEP amplitudes and increases latency

Answer

Hypothermia slows axonal conduction velocity and synaptic transmission, resulting in decreased tcMEP amplitudes and prolonged latencies.

Question 3

When is it appropriate to use epidural D-wave recording in addition to muscle MEPs?

Accepted Answer

For intramedullary spinal cord tumor resection where high sensitivity is critical

Answer

Epidural D-wave recording is particularly valuable during intramedullary spinal cord tumor resection because it provides a highly sensitive, stable measure of corticospinal tract integrity independent of anesthesia.

Question 4

The bite block placed during transcranial MEP monitoring is used to prevent:

Accepted Answer

Tongue laceration from jaw muscle MEP contractions

Answer

Transcranial electrical stimulation activates jaw muscles, causing biting movements that can lacerate the tongue or lips; a bite block prevents this injury.

Question 5

Which inhalational anesthetic has the LEAST suppressive effect on tcMEP compared to other volatile agents?

Accepted Answer

All volatile agents equally suppress MEPs

Answer

All volatile halogenated agents have comparable dose-dependent suppressive effects on tcMEP amplitudes; none is significantly superior for MEP preservation, which is why TIVA is preferred.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Motor Evoked Potentials (MEP) 3