Haloperidol-induced dyskinesias in the monkey.

Haloperidol (0.25 mg/kg i.m.) was injected daily for 6 months in six normal monkeys. Over a 24 hour period, the following symptoms could be observed: akathisia, circling, akinesia, choreoathetoid and dystonic movements, oro-facial dyskinesias and postural tremor with or without harmaline. Six months after cessation of haloperidol, harmaline-induced postural tremor could still be observed in all animals and oro-facial abnormal movements, in one monkey. The neuropathologic study of the experimental material did not disclose any alteration of the central nervous system.