Life-Threatening Hyperthermic Syndromes

Several neurological disorders can be caused by treatment with neuroleptic drugs, including acute and tardive dyskinesia, tremor, akathesia, and parkinsonism. Neuroleptic malignant syndrome (NMS) is the rarest and most dangerous disorder, occurring in 0.5%–0.14% of patients taking neuroleptic drugs. It is twice as common in men and 80% of patients are younger than 40 years. NMS is usually associated with regular therapeutic doses of haloperidol and fluphenazine (the most potent and most commonly prescribed neuroleptics). Previous exposure is not a prerequisite. NMS can be caused by other neuroleptics, including those used to treat nausea and vomiting, dissociative diseases, Tourette’s syndrome, Huntington’s disease, and agitation, as well as by some antidepressants. It can also result from withdrawal of dopaminergic drugs and may be identical to the malignant L-dopa withdrawal syndrome and acute akinetic crisis. In the past, death occurred in 25% of patients. The most common causes of death were pneumonia, hypotension, arrhymias, renal failure, and thromboembolism. Today, because of more widespread recognition and advances in supportive care, the mortality rate is approximately 10%.