Neuro: diabetic third nerve palsy: 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: diabetic third nerve palsy

Sample item

A 58-year-old diabetic hypertensive man has painful ptosis and ophthalmoplegia with normal pupillary reaction. Which statement is true?

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

The answer and the reasoning

C. Pupil sparing is typical due to ischaemia of the central nerve fibres

In ischaemic (microvascular) third nerve palsy the pupillary fibres on the periphery of the nerve are spared as they have a better blood supply. Recovery occurs in about 3 months. Pupil involvement suggests compression.

Option by option

  • A. It is due to an aneurysm in all cases

    Aneurysms usually involve the pupil.

  • B. It always needs urgent surgery

    Surgery is not needed urgently, and observation is advised.

  • C. Pupil sparing is typical due to ischaemia of the central nerve fibres (correct)

    Correct. Pupil sparing is typical of diabetic palsy.

  • D. The pupil is always dilated

    A dilated pupil points to a compressive cause.

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.

More Ophthalmology questions

Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is C, Pupil sparing is typical due to ischaemia of the central nerve fibres. In ischaemic (microvascular) third nerve palsy the pupillary fibres on the periphery of the nerve are spared as they have a better blood supply.

Why is "It is due to an aneurysm in all cases" not the answer?

Aneurysms usually involve the pupil.

Why is "It always needs urgent surgery" not the answer?

Surgery is not needed urgently, and observation is advised.

Why is "The pupil is always dilated" not the answer?

A dilated pupil points to a compressive cause.

What concept does this question test?

It tests Neuro: diabetic third nerve palsy in Ophthalmology. Recovery occurs in about 3 months. Pupil involvement suggests compression.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: diabetic third nerve palsy?

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.