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Cardiovascular

Neuroleptic Malignant Syndrome (NMS)



Key Features

  • Rare, life-threatening reaction to dopamine antagonists or dopaminergic drug withdrawal

  • Classic Tetrad:

    1. Extrapyramidal: Lead-pipe rigidity, bradykinesia, dystonia, tremor, dysphagia

    2. Hyperthermia: >39°C

    3. Autonomic Instability: Tachycardia, hypertension, labile BP, tachypnoea, sweating

    4. CNS: Confusion, mutism, altered mental state, incontinence, coma


Investigations

  • ↑ Creatine kinase (>3x ULN), leukocytosis, ↓ serum iron

  • EEG: Diffuse slowing


Causative Drugs


Dopamine Antagonists

  • 1st Gen: Haloperidol, chlorpromazine, droperidol

  • 2nd Gen: Risperidone, olanzapine, quetiapine, clozapine


Dopaminergic Drug Withdrawal

  • Levodopa, bromocriptine


DSM-5 Diagnostic Criteria


Major Criteria (All Required):

  • Dopamine antagonist exposure or dopaminergic drug withdrawal

  • Severe muscle rigidity

  • Hyperthermia (>38°C)


Other Criteria (≥2):

  • Tachycardia, labile BP, or sweating

  • ↑ CK or leukocytosis

  • Dysphagia, tremor

  • Altered mental status, mutism

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Management


Immediate Interventions

  • Stop causative agent (e.g., antipsychotics, anticholinergics, lithium)

  • Supportive care:

    • Airway management if required (e.g., intubation)

    • IV fluids for hypotension and cooling measures


Pharmacological Treatment

  • First-Line: Bromocriptine 2.5 mg PO/NG every 8 hrs (↑ to 5 mg every 4 hrs)

  • Second-Line: Dantrolene for refractory cases (toxicologist consultation)

  • Adjunct: Diazepam for agitation

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Additional Notes

  • Hyperthermia severity correlates with mortality → urgent cooling essential

  • Differentiate from serotonin syndrome (hyperreflexia vs. rigidity)

  • Therapy duration: 5–10 days for severe cases

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