Prevalence of persistent abnormal involuntary movements among patients in a Nigerian long-stay psychiatric unit.

226 patients in a Nigerian chronic psychiatric patients' unit were examined for the evidence of abnormal involuntary movements. 21 (9.3%) of the patients had the disorder. The prevalence rate was higher among the females (14.5%) than among the males (7%). All the 21 patients had the diagnosis of schizophrenia. Also, they were found to be of an older age group than the total population. In comparison with a control group, the development of persistent abnormal involuntary movement was found not to be related to the daily dose of neuroleptic drugs administered or to the duration of the illness. The disorder was thought to be an idiosyncratic reaction.