Neuroleptic Malignant Syndrome

Key Features

• A catatonia-like state manifested by

  • Extrapyramidal signs

  • Blood pressure changes

  • Altered consciousness

  • Hyperpyrexia

• Uncommon complication of antipsychotic treatment

• Comorbid affective disorder as well as concomitant lithium use may increase risk

• In most cases, occurs within 2 weeks of starting antipsychotic agent

Clinical Findings

• Muscle rigidity, involuntary movements, confusion, dysarthria, dysphagia

• Pallor, cardiovascular instability, pulmonary congestion, diaphoresis

• Can result in stupor, coma, death

• Differential diagnosis

  • Malignant catatonia

  • Malignant hyperthermia

  • Neurotoxic syndromes (including AIDS)

  • Various other conditions such as viral encephalitis, Wilson disease, central anticholinergic syndrome, and hypertonic states (eg, tetany, strychnine poisoning)

Diagnosis

• Elevated creatine kinase and leukocytosis with left shift in 50% of cases

Treatment

• Control of fever and intravenous fluid support

• Bromocriptine, 2.5–10.0 mg three times daily orally, and amantadine, 100–200 mg twice daily orally, can be tried

• Dantrolene, 50 mg intravenously as needed to maximum of 10 mg/kg/day, can alleviate rigidity

• Efficacy of these three agents as well as the use of calcium channel blockers and benzodiazepines remains controversial

• Electroconvulsive therapy has been used in resistant cases

• Clozapine has been used safely in patients with a history of neuroleptic malignant syndrome