Frequency and presentation of neuroleptic malignant syndrome in a large psychiatric hospital.

Neuroleptic malignant syndrome, a dangerous but little-known complication of antipsychotic drugs, is often assumed to be rare. To assess the frequency of the syndrome in a large psychiatric hospital, the authors first reviewed the literature and developed operational diagnostic criteria. Using these criteria to survey nearly 500 neuroleptic-treated patients admitted during a 1-year period, they found that seven (1.