
Neuroleptic Malignant Syndrome (NMS)
Key Features
Rare, life-threatening reaction to dopamine antagonists or dopaminergic drug withdrawal
Classic Tetrad:
Extrapyramidal: Lead-pipe rigidity, bradykinesia, dystonia, tremor, dysphagia
Hyperthermia: >39°C
Autonomic Instability: Tachycardia, hypertension, labile BP, tachypnoea, sweating
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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