Neuroleptic malignant syndrome: an overview

Neuroleptic Malignant Syndrome (NMS) is a specific, potentially lethal disorder related to the usage of dopamine antagonists. The four clinical hallmarks associated with this syndrome are 1) hyperthermia, 2) muscle rigidity, 3) mental status changes, and 4) autonomic instability. NMS has been estimated to occur in 0.02% to 3.23% of patients receiving dopamine antagonist therapy. The wide range of incidence is probably related to the variability in diagnostic criteria, survey techniques, and patient populations. Although the incidence of NMS is rare, the inherent mortality for patients developing NMS is significant. Fortunately, the mortality has gone from 25% before 1984 to 11.6% thereafter. This is probably related to greater awareness of the syndrome by the physician with early diagnosis and treatment and also to the advent of newer therapeutic modalities. Current methods of treatment include withdrawal of the dopamine antagonist, control of the hyperpyrexia, administration of a dopamine agonist, and the administration of dantrolene. Electroconvulsive therapy has been advocated in patients unresponsive to the above therapies. The reinstitution of dopamine antagonist therapy after an episode of NMS is possible. Specific protocols are available and are currently under revision by researchers. The current data indicate that the risk of a recurrence of NMS is about 30% if the protocol is followed.