Neuroanatomy: brainstem syndromes: practice question

A Anatomy 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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Anatomy · Neuroanatomy: brainstem syndromes

Sample item

After a basilar artery thrombosis, an alert man is quadriplegic and mute, with bilateral facial weakness and no horizontal eye movements. By which movements can he communicate?

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

The answer and the reasoning

B. Vertical eye movements and blinking

Locked-in syndrome results from a bilateral ventral pontine infarct that interrupts corticospinal and corticobulbar tracts and the abducens nuclei or horizontal gaze pathways. The midbrain pathways for vertical gaze and eyelid elevation lie above the lesion, and the dorsal reticular formation is spared, so he remains conscious. Patients communicate by blinking and vertical eye movements.

Option by option

  • A. Horizontal conjugate gaze

    Horizontal gaze is lost because the pontine gaze centre and abducens nuclei are affected.

  • B. Vertical eye movements and blinking (correct)

    Correct. Vertical gaze and blinking are preserved because they depend on the midbrain.

  • C. Tongue protrusion

    Tongue movement is lost because the corticobulbar fibres to the hypoglossal nucleus are interrupted.

  • D. Voluntary facial grimacing

    Facial movement is lost because the corticobulbar pathway to the facial nuclei is interrupted.

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 Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Vertical eye movements and blinking. Locked-in syndrome results from a bilateral ventral pontine infarct that interrupts corticospinal and corticobulbar tracts and the abducens nuclei or horizontal gaze pathways.

Why is "Horizontal conjugate gaze" not the answer?

Horizontal gaze is lost because the pontine gaze centre and abducens nuclei are affected.

Why is "Tongue protrusion" not the answer?

Tongue movement is lost because the corticobulbar fibres to the hypoglossal nucleus are interrupted.

Why is "Voluntary facial grimacing" not the answer?

Facial movement is lost because the corticobulbar pathway to the facial nuclei is interrupted.

What concept does this question test?

It tests Neuroanatomy: brainstem syndromes in Anatomy. The midbrain pathways for vertical gaze and eyelid elevation lie above the lesion, and the dorsal reticular formation is spared, so he remains conscious. Patients communicate by blinking and vertical eye movements.

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 Neuroanatomy: brainstem syndromes?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.