CNIM Brainstem Auditory Evoked Potentials (BAEP) 1 — Questions and Answers
Question 1: Which surgical procedure most commonly requires intraoperative BAEP monitoring?
- Lumbar spinal fusion
- Acoustic neuroma (vestibular schwannoma) resection (Correct answer)
- Hip arthroplasty
- Anterior cervical discectomy
Correct answer: Acoustic neuroma (vestibular schwannoma) resection
BAEP monitoring is most commonly used during acoustic neuroma resection to monitor auditory nerve and brainstem integrity during tumor removal.
Question 2: Wave V of the BAEP originates from which neural structure?
- Cochlear nerve (cranial nerve VIII)
- Superior olivary complex
- Lateral lemniscus and inferior colliculus (Correct answer)
- Auditory cortex
Correct answer: Lateral lemniscus and inferior colliculus
Wave V is generated by the lateral lemniscus and inferior colliculus junction and is the most robust and clinically important BAEP component for intraoperative monitoring.
Question 3: The standard acoustic stimulus used to elicit BAEPs intraoperatively is:
- Pure tone at 1000 Hz
- Broadband click stimulus (Correct answer)
- Speech noise
- Sinusoidal tone at 4000 Hz
Correct answer: Broadband click stimulus
Broadband click stimuli are standard for BAEP elicitation because they activate a broad frequency range of cochlear hair cells simultaneously, producing reliable wave patterns.
Question 4: An increase in Wave V latency of more than 1 ms from baseline during posterior fossa surgery is considered:
- Normal variability
- A significant alarm criterion (Correct answer)
- An electrode artifact
- A sign of improved conduction
Correct answer: A significant alarm criterion
An increase in Wave V latency of 1 ms or more from baseline is a widely accepted alarm criterion during posterior fossa surgery, indicating auditory pathway compromise.
Question 5: Which BAEP wave reflects activity at the level of the cochlear nerve (cranial nerve VIII)?
- Wave I (Correct answer)
- Wave III
- Wave V
- Wave VII
Correct answer: Wave I
Wave I of the BAEP is generated by the distal portion of cranial nerve VIII (cochlear nerve) near the cochlea and represents peripheral auditory nerve activity.
Question 6: To prevent masking noise from the non-test ear from affecting BAEP recordings, what is applied to the contralateral ear?
- Earplugs only
- Contralateral white noise masking (Correct answer)
- Contralateral click stimulation
- Nothing is needed
Correct answer: Contralateral white noise masking
White noise masking is applied to the contralateral (non-stimulated) ear to prevent cross-hearing, where the stimulus is heard by the opposite ear and generates a second BAEP.
CNIM Brainstem Auditory Evoked Potentials (BAEP) 1
Which surgical procedure most commonly requires intraoperative BAEP monitoring?