Neuro: sixth 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: sixth nerve palsy

Sample item

A child with raised intracranial pressure has an esotropia and inability to abduct one eye. The sixth nerve palsy in raised ICP is called:

AA sign of Wernicke encephalopathyBA true localising signCA sign of cavernous sinus thrombosisDA false localising sign

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

The answer and the reasoning

D. A false localising sign

The abducens nerve has the longest intracranial course and is stretched over the petrous apex when ICP rises or the brainstem shifts, so palsy does not localise the lesion. It also occurs in Gradenigo syndrome and after lumbar puncture. Diplopia is worse on looking toward the paretic side.

Option by option

A. A sign of Wernicke encephalopathy
Wernicke encephalopathy has bilateral gaze palsies and nystagmus.
B. A true localising sign
It does not point to the actual site of pathology.
C. A sign of cavernous sinus thrombosis
It can occur in cavernous sinus disease but is not diagnostic of it.
D. A false localising sign (correct)
Correct. It is a false localising sign.

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 Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is D, A false localising sign. The abducens nerve has the longest intracranial course and is stretched over the petrous apex when ICP rises or the brainstem shifts, so palsy does not localise the lesion.

Why is "A sign of Wernicke encephalopathy" not the answer?

Wernicke encephalopathy has bilateral gaze palsies and nystagmus.

Why is "A true localising sign" not the answer?

It does not point to the actual site of pathology.

Why is "A sign of cavernous sinus thrombosis" not the answer?

It can occur in cavernous sinus disease but is not diagnostic of it.

What concept does this question test?

It tests Neuro: sixth nerve palsy in Ophthalmology. It also occurs in Gradenigo syndrome and after lumbar puncture. Diplopia is worse on looking toward the paretic side.

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: sixth 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.