History and exam

Key diagnostic factors

common

history of exposure to antipsychotic medications

NMS should generally be diagnosed only in the context of antipsychotic medication administration.[1][5][28][40][41][42] However, syndromes resembling NMS have been reported with a variety of medications and intoxications.

Administration of high doses of antipsychotics at onset of treatment and intramuscular administration may increase the risk. All antipsychotic medications have been associated with NMS, presumably through their antagonism of dopamine D2 receptors.[24] No antipsychotic drug is believed to entail more risk than the others, although severity may be less with second-generation antipsychotics than with first-generation antipsychotics.

history of abrupt withdrawal of dopaminergic drugs

NMS can occur when dopaminergic drugs (e.g., levodopa, bromocriptine) are abruptly withdrawn.[24][26]

altered mental status

Confusion, delirium, stupor.

muscle rigidity

Lead-pipe or generalized hypertonia is a cardinal feature. Generalized rigidity may be associated with tremor, akinesia, dystonia, trismus, myoclonus, dysarthria, and dysphagia. Patients may have sialorrhea and rhabdomyolysis.[35]

autonomic dysfunction

Tachycardia, labile hypertension, diaphoresis, tachypnea, urinary incontinence, pallor.

hyperthermia

Temperature may be quite high and rise so quickly that aggressive external cooling interventions must be applied.

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