Vestibular disorders: subclavian steal syndrome: 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 · Vestibular disorders: subclavian steal syndrome

Sample item

A 65-year-old smoker has episodes of vertigo and blurred vision when he exercises his left arm, which also aches. Blood pressure is 30 mmHg lower in the left arm than the right. What is the mechanism?

AReversed vertebral artery flow from proximal subclavian stenosisBCompression of the vestibulocochlear nerve by a cerebellopontine angle tumourCEmbolism to the posterior inferior cerebellar arteryDCompression of the vertebral artery by cervical spondylosis

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

The answer and the reasoning

A. Reversed vertebral artery flow from proximal subclavian stenosis

Stenosis of the subclavian artery proximal to the vertebral origin lowers distal pressure, so exercise of the arm draws blood retrograde down the vertebral artery from the basilar circulation. This causes posterior circulation symptoms with a blood pressure difference between arms.

Option by option

A. Reversed vertebral artery flow from proximal subclavian stenosis (correct)
Correct. Exercise of the affected arm reverses flow in the ipsilateral vertebral artery, depriving the hindbrain.
B. Compression of the vestibulocochlear nerve by a cerebellopontine angle tumour
A cerebellopontine angle tumour causes progressive unilateral hearing loss and not exertional vertigo.
C. Embolism to the posterior inferior cerebellar artery
An embolus to the posterior inferior cerebellar artery gives Wallenberg syndrome without arm claudication.
D. Compression of the vertebral artery by cervical spondylosis
Spondylotic compression causes vertigo with neck rotation and does not produce an arm pressure difference.

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 A, Reversed vertebral artery flow from proximal subclavian stenosis. Stenosis of the subclavian artery proximal to the vertebral origin lowers distal pressure, so exercise of the arm draws blood retrograde down the vertebral artery from the basilar circulation.

Why is "Compression of the vestibulocochlear nerve by a cerebellopontine angl…" not the answer?

A cerebellopontine angle tumour causes progressive unilateral hearing loss and not exertional vertigo.

Why is "Embolism to the posterior inferior cerebellar artery" not the answer?

An embolus to the posterior inferior cerebellar artery gives Wallenberg syndrome without arm claudication.

Why is "Compression of the vertebral artery by cervical spondylosis" not the answer?

Spondylotic compression causes vertigo with neck rotation and does not produce an arm pressure difference.

What concept does this question test?

It tests Vestibular disorders: subclavian steal syndrome in ENT. This causes posterior circulation symptoms with a blood pressure difference between arms.

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: subclavian steal syndrome?

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.