Vestibular disorders: brainstem response audiometry in retrocochlear lesions: practice question

A ENT question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

ENT · Vestibular disorders: brainstem response audiometry in retrocochlear lesions

Sample item

A patient with asymmetric sensorineural loss has a brainstem evoked response audiogram. Which finding favours a retrocochlear lesion such as a vestibular schwannoma over a cochlear one?

ADelay of all waves with normal interpeak intervalsBAbsent wave I with normal later wavesCShortened wave V latency with large amplitudeDProlonged I to V interpeak latency with wave I present

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Prolonged I to V interpeak latency with wave I present

In a cochlear loss, all waves may be delayed equally, so the interpeak intervals remain normal. A lesion of the eighth nerve or brainstem delays the later waves relative to wave I, so the I to V interval is prolonged. This is why ABR with interaural latency comparison is a screening test for schwannoma, with MRI as the definitive study.

Option by option

A. Delay of all waves with normal interpeak intervals
Uniform delay with normal interpeak intervals suggests a cochlear or conductive cause rather than a nerve lesion.
B. Absent wave I with normal later waves
Absent wave I with normal later waves is not a recognised pattern of a retrocochlear lesion.
C. Shortened wave V latency with large amplitude
A shortened wave V is not a feature of schwannoma; retrocochlear lesions prolong wave V latency.
D. Prolonged I to V interpeak latency with wave I present (correct)
Correct. A prolonged I to V interval with a present wave I places the delay beyond the cochlea.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this ENT question

What is the answer to this ENT question?

The best answer is D, Prolonged I to V interpeak latency with wave I present. In a cochlear loss, all waves may be delayed equally, so the interpeak intervals remain normal.

Why is "Delay of all waves with normal interpeak intervals" not the answer?

Uniform delay with normal interpeak intervals suggests a cochlear or conductive cause rather than a nerve lesion.

Why is "Absent wave I with normal later waves" not the answer?

Absent wave I with normal later waves is not a recognised pattern of a retrocochlear lesion.

Why is "Shortened wave V latency with large amplitude" not the answer?

A shortened wave V is not a feature of schwannoma; retrocochlear lesions prolong wave V latency.

What concept does this question test?

It tests Vestibular disorders: brainstem response audiometry in retrocochlear lesions in ENT. A lesion of the eighth nerve or brainstem delays the later waves relative to wave I, so the I to V interval is prolonged. This is why ABR with interaural latency comparison is a screening test for schwannoma, with MRI as the definitive study.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Vestibular disorders: brainstem response audiometry in retrocochlear lesions?

Learn tuning fork results and audiogram patterns by sketching them. Then use the flashcards and the other ENT questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.