Ear and audiology: superior canal dehiscence work-up: 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.

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ENT · Ear and audiology: superior canal dehiscence work-up

Sample item

A 40-year-old has vertigo triggered by loud sounds and straining, autophony, and a conductive hearing loss with a normal tympanic membrane. Tympanometry is normal and acoustic reflexes are present. Which investigation best confirms the diagnosis?

APlain radiograph of the mastoid in Schuller viewBContrast MRI of the internal auditory canalCCT venography of the sigmoid sinusDHigh-resolution temporal bone CT with reformats along the superior canal

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

The answer and the reasoning

D. High-resolution temporal bone CT with reformats along the superior canal

A conductive loss despite normal tympanometry and present acoustic reflexes means the air-bone gap is not from the ossicles; a third mobile window from a dehiscent superior canal is the cause. High-resolution thin-slice CT with reformats in the plane of the canal shows the bony defect. Vestibular evoked myogenic potentials show a low threshold.

Option by option

A. Plain radiograph of the mastoid in Schuller view
A Schuller view cannot show a thin bony defect of the canal roof.
B. Contrast MRI of the internal auditory canal
Contrast MRI of the internal auditory canal looks for a vestibular schwannoma, which does not give sound-induced vertigo.
C. CT venography of the sigmoid sinus
Venography would assess a venous sinus problem such as pulsatile tinnitus, not this picture.
D. High-resolution temporal bone CT with reformats along the superior canal (correct)
Correct. Thin-slice CT in the plane of the canal demonstrates the dehiscence.

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, High-resolution temporal bone CT with reformats along the superior canal. A conductive loss despite normal tympanometry and present acoustic reflexes means the air-bone gap is not from the ossicles; a third mobile window from a dehiscent superior canal is the cause.

Why is "Plain radiograph of the mastoid in Schuller view" not the answer?

A Schuller view cannot show a thin bony defect of the canal roof.

Why is "Contrast MRI of the internal auditory canal" not the answer?

Contrast MRI of the internal auditory canal looks for a vestibular schwannoma, which does not give sound-induced vertigo.

Why is "CT venography of the sigmoid sinus" not the answer?

Venography would assess a venous sinus problem such as pulsatile tinnitus, not this picture.

What concept does this question test?

It tests Ear and audiology: superior canal dehiscence work-up in ENT. High-resolution thin-slice CT with reformats in the plane of the canal shows the bony defect. Vestibular evoked myogenic potentials show a low threshold.

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 Ear and audiology: superior canal dehiscence work-up?

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.