Neuroanatomy: normal pressure hydrocephalus: 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: normal pressure hydrocephalus

Sample item

A 72-year-old man has a short-stepped, magnetic gait, urinary urgency and mild cognitive slowing. CT shows enlarged ventricles without cortical atrophy, and the opening pressure at lumbar puncture is normal. Which mechanism underlies his condition?

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

The answer and the reasoning

D. Impaired CSF absorption at the arachnoid granulations

Normal pressure hydrocephalus is a communicating hydrocephalus in which CSF absorption is reduced, producing ventricular enlargement with a normal or intermittently raised pressure. The triad of gait disturbance, urinary incontinence and dementia improves with shunting.

Option by option

  • A. Cortical atrophy causing ex vacuo ventricular dilatation

    Ex vacuo dilatation accompanies cortical atrophy, which is absent here.

  • B. Overproduction of CSF by the choroid plexus

    Overproduction is rare and is typical of choroid plexus papilloma.

  • C. Obstruction of the cerebral aqueduct

    Aqueduct obstruction causes non-communicating hydrocephalus with raised pressure and a small fourth ventricle.

  • D. Impaired CSF absorption at the arachnoid granulations (correct)

    Correct. Reduced absorption at the arachnoid granulations enlarges the ventricles without sustained high pressure.

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 D, Impaired CSF absorption at the arachnoid granulations. Normal pressure hydrocephalus is a communicating hydrocephalus in which CSF absorption is reduced, producing ventricular enlargement with a normal or intermittently raised pressure.

Why is "Cortical atrophy causing ex vacuo ventricular dilatation" not the answer?

Ex vacuo dilatation accompanies cortical atrophy, which is absent here.

Why is "Overproduction of CSF by the choroid plexus" not the answer?

Overproduction is rare and is typical of choroid plexus papilloma.

Why is "Obstruction of the cerebral aqueduct" not the answer?

Aqueduct obstruction causes non-communicating hydrocephalus with raised pressure and a small fourth ventricle.

What concept does this question test?

It tests Neuroanatomy: normal pressure hydrocephalus in Anatomy. The triad of gait disturbance, urinary incontinence and dementia improves with shunting.

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 Neuroanatomy: normal pressure hydrocephalus?

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.