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NMS — MRCPsych Paper B MCQ

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HardSchizophrenia & PsychosisNMSMRCPsych Paper B

A 25-year-old man treated with olanzapine 20 mg daily develops severe neuroleptic malignant syndrome, with a temperature of 40.5°C, generalised lead-pipe rigidity, autonomic instability and a markedly elevated creatine kinase concentration. Olanzapine is stopped and he receives intensive supportive management, including intravenous fluids and external cooling. Because severe rigidity and hyperthermia persist, the physician considers an adjunct that acts directly on skeletal muscle by inhibiting calcium release from the sarcoplasmic reticulum. Which medication has this action?

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Correct answer: D — Dantrolene

Dantrolene is the correct answer. It is a directly acting skeletal-muscle relaxant that reduces calcium release from the sarcoplasmic reticulum and may therefore be considered in severe NMS with prominent rigidity and hyperthermia, alongside cessation of the causative drug and intensive supportive care. Bromocriptine and amantadine instead aim to restore central dopaminergic activity and are also possible NMS adjuncts; this is why the original question asking which drug is “most commonly used” was not uniquely answerable. Diazepam may be used as an adjunct but does not directly inhibit skeletal-muscle calcium release. Procyclidine treats antipsychotic-induced parkinsonism or acute dystonia, not NMS, and its anticholinergic effects may impair heat dissipation.

Reference: Royal College of Psychiatrists. CR190: The risks and benefits of high-dose antipsychotic medication, Neuroleptic malignant syndrome—Management. Revised 2023. https://www.rcpsych.ac.uk/docs/default-source/improving-care/better-mh-policy/college-reports/college-report-cr190.pdf