EEG Evoked Potentials 2

Question 1

A unilaterally prolonged P100 latency on visual evoked potential testing is most characteristically associated with which condition?

Accepted Answer

Demyelinating optic neuritis (multiple sclerosis)

Answer

Demyelinating optic neuritis, most commonly seen in multiple sclerosis, slows conduction along the optic nerve, resulting in a prolonged P100 latency that may persist even after clinical recovery.

Question 2

In a BAEP recording, absent Wave I with relatively preserved Waves III and V most likely indicates pathology at which level?

Accepted Answer

Cochlea or cochlear nerve peripheral to the brainstem

Answer

Wave I reflects the distal cochlear nerve action potential; its absence with central waves preserved indicates peripheral auditory dysfunction (cochlea or nerve), not brainstem pathology.

Question 3

During intraoperative neurophysiological monitoring, a sudden 50% decrease in SSEP amplitude or a 10% increase in latency should prompt what immediate action?

Accepted Answer

Alert the surgical team immediately

Answer

The '50/10 rule' is the standard alert criterion: a >50% amplitude drop or >10% latency increase warrants immediate notification of the surgeon to allow corrective intervention before permanent injury.

Question 4

What is the upper limit of normal for the interpeak latency I–V (IPL I–V) in BAEPs recorded from a typical adult?

Accepted Answer

Less than 4.4 ms

Answer

The IPL I–V, representing total brainstem conduction time, normally does not exceed approximately 4.4 ms; values beyond this suggest central conduction slowing.

Question 5

Bilateral prolongation of SSEP cortical latencies with normal peripheral nerve and plexus responses most strongly suggests pathology at which level?

Accepted Answer

Cervical spinal cord (myelopathy)

Answer

Normal peripheral potentials with delayed cortical responses imply a central conduction abnormality; bilateral symmetric involvement points to the cervical cord rather than unilateral brain pathology.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Evoked Potentials 2