Neuroanatomy: dorsal midbrain syndrome: 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: dorsal midbrain syndrome

Sample item

A 14-year-old boy with headache and vomiting cannot look upwards, his eyelids are retracted, and pupils react better to accommodation than to light. MRI shows a pineal region tumour with hydrocephalus. Which structure is compressed?

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

The answer and the reasoning

B. Dorsal midbrain (pretectal area and superior colliculus)

Parinaud syndrome results from compression of the dorsal midbrain by pineal tumours. The vertical gaze centres (rostral interstitial nucleus of the MLF) and the pretectal fibres of the light reflex are affected, causing upgaze palsy, light-near dissociation and lid retraction. Obstruction of the aqueduct causes hydrocephalus.

Option by option

  • A. Lateral geniculate body

    The lateral geniculate body is the visual relay, and its damage causes homonymous field defects.

  • B. Dorsal midbrain (pretectal area and superior colliculus) (correct)

    The dorsal midbrain houses the pretectal area and vertical gaze centres, which are compressed by pineal tumours.

  • C. Cerebral peduncles of the ventral midbrain

    The cerebral peduncles carry descending motor fibres and their damage gives hemiparesis.

  • D. Facial colliculus in the floor of the fourth ventricle

    The facial colliculus overlies the abducens nucleus and facial genu, and a lesion there gives horizontal gaze palsy and facial weakness.

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, Dorsal midbrain (pretectal area and superior colliculus). Parinaud syndrome results from compression of the dorsal midbrain by pineal tumours.

Why is "Lateral geniculate body" not the answer?

The lateral geniculate body is the visual relay, and its damage causes homonymous field defects.

Why is "Cerebral peduncles of the ventral midbrain" not the answer?

The cerebral peduncles carry descending motor fibres and their damage gives hemiparesis.

Why is "Facial colliculus in the floor of the fourth ventricle" not the answer?

The facial colliculus overlies the abducens nucleus and facial genu, and a lesion there gives horizontal gaze palsy and facial weakness.

What concept does this question test?

It tests Neuroanatomy: dorsal midbrain syndrome in Anatomy. The vertical gaze centres (rostral interstitial nucleus of the MLF) and the pretectal fibres of the light reflex are affected, causing upgaze palsy, light-near dissociation and lid retraction. Obstruction of the aqueduct causes hydrocephalus.

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: dorsal midbrain syndrome?

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.