Progression of symptoms in neuroleptic malignant syndrome

The neuroleptic malignant syndrome (NMS) is a rare but potentially fatal disorder characterized by mental-status changes, muscle rigidity, hyperthermia, and autonomic dysfunction. Systematic examination of early signs and the progression of symptoms in NMS may be worthwhile to facilitate prompt recognition and interventions to abort the syndrome in its incipient stage. The authors present the results of a preliminary review of the temporal sequence of the four predominant signs of NMS as described in 340 clinical reports of NMS in the literature. Of all order implications, 70.5% were consistent with the sequence of mental-status changes, rigidity, hyperthermia, and autonomic dysfunction. Changes in either mental status or rigidity were the initial manifestations of NMS in 82.3% of cases with a single presenting sign and were significantly more likely to be observed before hyperthermia and autonomic dysfunction. Methodological limitations of these data and clinical implications are discussed.