CNIM Brainstem Auditory Evoked Potentials (BAEP) 3

Question 1

When monitoring hearing preservation during acoustic neuroma surgery, which BAEP parameter is most predictive of postoperative hearing outcome?

Accepted Answer

Wave V latency and amplitude preservation throughout surgery

Answer

Preservation of Wave V latency and amplitude throughout surgery is most predictive of postoperative hearing preservation after acoustic neuroma resection.

Question 2

Which electrode placement is used to record the Fz (frontal) reference for BAEP monitoring?

Accepted Answer

Frontal midline (forehead)

Answer

Fz (mid-forehead) serves as the non-inverting reference electrode in BAEP recordings, paired with the ipsilateral earlobe or mastoid as the inverting input.

Question 3

Hypothermia during posterior fossa surgery affects BAEPs by:

Accepted Answer

Prolonging all wave latencies without amplitude loss

Answer

Hypothermia slows neural conduction, prolonging all BAEP wave latencies in a predictable fashion without abolishing responses, which must be accounted for when interpreting intraoperative changes.

Question 4

The standard BAEP amplitude alarm criterion during intraoperative monitoring is:

Accepted Answer

50% decrease in Wave V amplitude

Answer

A 50% or greater decrease in Wave V amplitude from baseline is the standard alarm threshold for BAEPs, complementing the 1 ms latency criterion.

Question 5

During microvascular decompression (MVD) for hemifacial spasm, BAEP monitoring is used because:

Accepted Answer

The auditory nerve (CNVIII) runs adjacent to the facial nerve in the posterior fossa and can be injured during surgery

Answer

During MVD for hemifacial spasm, the auditory nerve runs near the facial nerve root entry zone; BAEP monitoring protects hearing by detecting auditory pathway compromise during dissection.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Brainstem Auditory Evoked Potentials (BAEP) 3