CNIM Somatosensory Evoked Potentials (SSEP)

Question 1

What is the primary neural pathway monitored by upper extremity SSEP during intraoperative monitoring?

Accepted Answer

Dorsal column-medial lemniscal pathway

Answer

Upper extremity SSEPs monitor the dorsal column-medial lemniscal pathway, which carries proprioception and fine touch from the periphery to the cortex.

Question 2

Which SSEP component is considered the most clinically significant cortical response when monitoring median nerve stimulation?

Accepted Answer

N20

Answer

The N20 is the primary cortical response generated in the contralateral primary somatosensory cortex and is the most clinically significant component for median nerve SSEP monitoring.

Question 3

A 50% decrease in SSEP amplitude combined with a 10% increase in latency is generally considered:

Accepted Answer

A significant alarm criterion requiring intervention

Answer

A 50% amplitude decrease with a 10% latency increase meets the standard CNIM alarm criteria and requires immediate notification of the surgical team.

Question 4

Which electrode placement is used to record the Erb's point potential during median nerve SSEP?

Accepted Answer

Ipsilateral to stimulation at the clavicle

Answer

Erb's point (N9) is recorded ipsilateral to the stimulation site over the brachial plexus at the clavicle, representing a peripheral nerve potential.

Question 5

What does the P37 component represent in lower extremity SSEP monitoring via posterior tibial nerve stimulation?

Accepted Answer

Cortical response at the vertex

Answer

The P37 is a positive cortical potential recorded at the vertex (Cz) representing activation of the primary somatosensory cortex after posterior tibial nerve stimulation.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Somatosensory Evoked Potentials (SSEP)