Organic mental disorders: carbon monoxide poisoning sequelae: practice question

A Psychiatry 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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Psychiatry · Organic mental disorders: carbon monoxide poisoning sequelae

Sample item

A man recovers fully after carbon monoxide poisoning, but two weeks later he becomes apathetic, forgetful and parkinsonian. MRI shows symmetric lesions in a deep grey nucleus. Which structure is classically involved?

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

The answer and the reasoning

D. Globus pallidus

Carbon monoxide poisoning classically injures the globus pallidus, and a delayed neuropsychiatric syndrome with cognitive decline, apathy, parkinsonism and incontinence can appear 2 to 40 days after apparent recovery. The pallidum is vulnerable because of its poor watershed blood supply and high metabolic demand.

Option by option

  • A. Mamillary bodies

    Mamillary bodies are damaged in thiamine deficiency.

  • B. Amygdala

    The amygdalae are bilaterally damaged in Kluver-Bucy syndrome.

  • C. Pons

    The pons is damaged in osmotic demyelination.

  • D. Globus pallidus (correct)

    Correct. Bilateral pallidal necrosis is the characteristic lesion.

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 Psychiatry question

What is the answer to this Psychiatry question?

The best answer is D, Globus pallidus. Carbon monoxide poisoning classically injures the globus pallidus, and a delayed neuropsychiatric syndrome with cognitive decline, apathy, parkinsonism and incontinence can appear 2 to 40 days after apparent recovery.

Why is "Mamillary bodies" not the answer?

Mamillary bodies are damaged in thiamine deficiency.

Why is "Amygdala" not the answer?

The amygdalae are bilaterally damaged in Kluver-Bucy syndrome.

Why is "Pons" not the answer?

The pons is damaged in osmotic demyelination.

What concept does this question test?

It tests Organic mental disorders: carbon monoxide poisoning sequelae in Psychiatry. The pallidum is vulnerable because of its poor watershed blood supply and high metabolic demand.

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 Organic mental disorders: carbon monoxide poisoning sequelae?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry 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.