Neuroleptic malignant syndrome: physiological and laboratory findings in a series of nine cases.

A series of nine cases of neuroleptic malignant syndrome (NMS) are presented with peak measures of autonomic dysfunction and laboratory findings. Urine abnormalities, consisting of proteinuria, casts, or cells, were an associated finding in these cases. Severe hypophosphatemia was present in two patients. Relative dehydration before the onset of the syndrome in eight of the nine patients supports the suggestion that it is a risk factor for the development of NMS. The withdrawal of dopamine agonists was also seen as a trigger for NMS. Autonomic instability and muscular rigidity occurred separately in some cases. Creatine phosphokinase elevation and fever did not necessarily parallel the duration or the degree of muscular rigidity, and this finding supports the idea of a central cause for the symptoms. A systematic approach is presented for the evaluation and treatment of NMS. Observations implicate central dopaminergic mechanisms in the regulation of autonomic functioning and the maintenance of peripheral muscle membrane stability.