Neuroleptic malignant syndrome: observations on altered consciousness.

A young man with a previously untreated schizophrenia developed a neuroleptic malignant syndrome (NMS) on the second day of neuroleptic treatment. The dominant symptom was deep coma. The NMS occurred on the second day of neuroleptic therapy with rapidly progressing mental deterioration, temperature elevation, and extrapyramidal signs. After anticholinergics were injected the patient regained consciousness. This suggests that a cholinergic hyperactivity in the central nervous system (rather than hyperthermia) is responsible for the disturbance of consciousness in NMS. The experimental evidence that central cholinergic systems are stimulated by neuroleptics is discussed. It is concluded that anticholinergics might be helpful in treating coma during NMS.