CNIM Somatosensory Evoked Potentials (SSEP) 3

Question 1

Interpeak latency between N20 and N13 reflects conduction through which segment of the somatosensory pathway?

Accepted Answer

Cervical spinal cord to cortex

Answer

The N13–N20 interpeak latency reflects conduction time from the cervical spinal cord through the brainstem and thalamus to the primary somatosensory cortex.

Question 2

Which stimulation parameter is most important for obtaining optimal SSEP responses during intraoperative monitoring?

Accepted Answer

Pulse duration and current intensity sufficient to produce a motor twitch

Answer

Using a pulse duration and current intensity that produces a small motor twitch (supramaximal sensory stimulation) ensures reliable activation of large-diameter sensory fibers for SSEP recording.

Question 3

A unilateral loss of SSEP with the contralateral side intact during cervical spine surgery most likely suggests:

Accepted Answer

Ipsilateral posterior spinal cord or nerve root compromise

Answer

Unilateral SSEP loss during cervical spine surgery suggests ipsilateral dorsal column or nerve root compromise at the surgical level, requiring immediate surgeon notification.

Question 4

What is the typical stimulation pulse duration used for median nerve SSEP in intraoperative monitoring?

Accepted Answer

0.2 ms

Answer

A pulse duration of approximately 0.2 ms (200 microseconds) is standard for peripheral nerve stimulation during intraoperative SSEP monitoring.

Question 5

Why are reference baselines obtained after anesthetic induction but before surgical incision in SSEP monitoring?

Accepted Answer

To establish anesthetic-state baselines that account for drug effects before comparing surgical changes

Answer

Baselines are obtained after stable anesthesia induction so that subsequent changes can be compared against an anesthetic-adjusted reference, isolating surgically induced changes.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Somatosensory Evoked Potentials (SSEP) 3