Neuro-ophthalmology and pupils: Weber syndrome: practice question

A Ophthalmology 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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Ophthalmology · Neuro-ophthalmology and pupils: Weber syndrome

Sample item

A 62-year-old hypertensive man has a left ptosis, a dilated left pupil with the eye down and out, and weakness of the right arm and leg. Where is the lesion?

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

The answer and the reasoning

D. Left cerebral peduncle in the midbrain

A lesion of the ventral midbrain that damages the exiting oculomotor fascicles and the cerebral peduncle gives an ipsilateral third nerve palsy with contralateral hemiparesis, known as Weber syndrome. A cavernous sinus lesion would not cause hemiparesis. The picture is usually due to a midbrain infarct.

Option by option

  • A. Left cavernous sinus

    Cavernous sinus disease gives ophthalmoplegia and sensory loss but no hemiparesis.

  • B. Left occipital lobe

    An occipital lobe lesion causes field loss without ocular motor palsy.

  • C. Right pons

    A right pontine lesion would cause a sixth or seventh nerve sign, not a third nerve palsy.

  • D. Left cerebral peduncle in the midbrain (correct)

    Correct. Ipsilateral third nerve palsy with contralateral hemiparesis localises to the midbrain peduncle.

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.

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Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is D, Left cerebral peduncle in the midbrain. A lesion of the ventral midbrain that damages the exiting oculomotor fascicles and the cerebral peduncle gives an ipsilateral third nerve palsy with contralateral hemiparesis, known as Weber syndrome.

Why is "Left cavernous sinus" not the answer?

Cavernous sinus disease gives ophthalmoplegia and sensory loss but no hemiparesis.

Why is "Left occipital lobe" not the answer?

An occipital lobe lesion causes field loss without ocular motor palsy.

Why is "Right pons" not the answer?

A right pontine lesion would cause a sixth or seventh nerve sign, not a third nerve palsy.

What concept does this question test?

It tests Neuro-ophthalmology and pupils: Weber syndrome in Ophthalmology. A cavernous sinus lesion would not cause hemiparesis. The picture is usually due to a midbrain infarct.

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 Neuro-ophthalmology and pupils: Weber syndrome?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology 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.