A 45-year-old man is brought to the emergency room because of fever and increasing confusion for the past 2 days. He has paranoid schizophrenia treated with chlorpromazine. He appears diaphoretic. His temperature is 40.6 C (105.1 F), blood pressure is 157/90 mm Hg, pulse is 102/min, and respirations are 20/min. Neurologic examination shows psychomotor agitation and incoherent speech. There is generalized muscle rigidity. His deep tendon reflexes are decreased bilaterally. Serum laboratory analysis shows a leukocyte count of 11,300/mm3 and serum creatine kinase concentration of 945 U/L. Which of the following is the most likely explanation for this patient's current symptoms?

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Quizplus · Accepted Answer

Eductional Objective: Neuroleptic malignant syndrome (NMS) is an adverse reaction to antipsychotic medication characterized by severe "lead-pipe" rigidity, hyperthermia, sympathetic hyperactivity, and mental status changes.  NMS is characterized by severe rigidity rather than the neuromuscular irritability (eg, hyperreflexia, myoclonus) seen in serotonin syndrome.

A 45-Year-Old Man Is Brought to the Emergency Room Because