EDT Evoked Potentials

Question 1

Which nerve is typically stimulated at the wrist to obtain upper extremity somatosensory evoked potentials (SSEPs)?

Accepted Answer

Median nerve

Answer

The median nerve at the wrist is the standard stimulation site for upper extremity SSEPs due to its reliable brachial plexus and cortical responses.

Question 2

What does 'P100' refer to in visual evoked potential (VEP) recordings?

Accepted Answer

A positive polarity peak occurring approximately 100 ms after the visual stimulus

Answer

P100 is a positive-polarity component peaking around 100 ms post-stimulus and is the primary waveform evaluated in clinical VEP studies.

Question 3

What type of stimulus is used to elicit pattern-reversal visual evoked potentials?

Accepted Answer

A checkerboard pattern that alternates black and white squares at a set rate

Answer

Pattern-reversal VEPs use a contrast-reversing checkerboard that produces more reproducible and reliable responses than flash stimuli.

Question 4

The N20 component recorded over the contralateral scalp in median nerve SSEPs is generated by which structure?

Accepted Answer

Primary somatosensory cortex

Answer

N20 is the earliest cortical response to median nerve stimulation and is generated in the contralateral primary somatosensory cortex (area 3b).

Question 5

What is the primary purpose of signal averaging in evoked potential recordings?

Accepted Answer

To improve signal-to-noise ratio by canceling random background EEG activity

Answer

Averaging enhances the time-locked evoked response while random background noise cancels out mathematically, improving SNR proportional to the square root of the number of averages.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT Evoked Potentials