Complications and emergencies: osmotic demyelination after hyponatraemia correction: practice question

A Anaesthesia 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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Anaesthesia · Complications and emergencies: osmotic demyelination after hyponatraemia correction

Sample item

A malnourished man with chronic alcohol use and a serum sodium of 108 mmol/L is treated, and the sodium reaches 130 mmol/L within 24 hours. Three days later he becomes dysarthric and develops spastic quadriparesis with pseudobulbar signs. What is the diagnosis?

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

The answer and the reasoning

B. Osmotic demyelination syndrome

Too rapid correction of chronic hyponatraemia dehydrates brain cells that have adapted to low osmolality, and pontine and extrapontine oligodendrocytes are damaged. Symptoms appear two to six days later as dysarthria, dysphagia, spastic quadriparesis and a locked-in state. Alcohol use and malnutrition are risk factors.

Option by option

  • A. Basilar artery thrombosis with brainstem infarction

    Basilar thrombosis presents abruptly with brainstem signs and would not follow a stepwise delay linked to correction.

  • B. Osmotic demyelination syndrome (correct)

    Correct. A delayed brainstem syndrome after rapid sodium correction in a malnourished alcoholic is osmotic demyelination.

  • C. Cerebral oedema from untreated hyponatraemia

    Cerebral oedema from hyponatraemia would worsen with low sodium and not appear days after sodium has been raised.

  • D. Wernicke encephalopathy from thiamine deficiency

    Wernicke encephalopathy causes confusion, ophthalmoplegia and ataxia and is not triggered by sodium correction.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is B, Osmotic demyelination syndrome. Too rapid correction of chronic hyponatraemia dehydrates brain cells that have adapted to low osmolality, and pontine and extrapontine oligodendrocytes are damaged.

Why is "Basilar artery thrombosis with brainstem infarction" not the answer?

Basilar thrombosis presents abruptly with brainstem signs and would not follow a stepwise delay linked to correction.

Why is "Cerebral oedema from untreated hyponatraemia" not the answer?

Cerebral oedema from hyponatraemia would worsen with low sodium and not appear days after sodium has been raised.

Why is "Wernicke encephalopathy from thiamine deficiency" not the answer?

Wernicke encephalopathy causes confusion, ophthalmoplegia and ataxia and is not triggered by sodium correction.

What concept does this question test?

It tests Complications and emergencies: osmotic demyelination after hyponatraemia correction in Anaesthesia. Symptoms appear two to six days later as dysarthria, dysphagia, spastic quadriparesis and a locked-in state. Alcohol use and malnutrition are risk factors.

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 Complications and emergencies: osmotic demyelination after hyponatraemia correction?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.