The neuroleptic malignant syndrome is an uncommon and potentially lethal complication of treatment with antipsychotic medication (1). This syndrome is characterized by severe fever, altered mental status, autonomic instability, and generalized skeletal muscle rigidity. Also, leukocytosis and elevations in creatine kinase may be prominent. To date, treatment has consisted mainly of supportive measures (1-5).
Recently, attention has been drawn to the similarity between the neuroleptic malignant syndrome and malignant hyperthermia, a pharmacogenetic disorder of skeletal muscle (1). Patients with malignant hyperthermia are susceptible to an acute, life-threatening, hyperthermic reaction to certain pharmacologic agents (6). Dantrolene sodium has been used successfully