Dyskinesias following treatment with 5-HT re-uptake inhibitors.

Three cases of dyskinesia attributable to selective serotonergic antidepressant drugs are presented. The patients were not on other medication nor had they been in preceding weeks. The movement disorder disappeared on cessation of the drug within a time period corresponding to the expected wash-out for the different preparations. The emergence of dyskinesic symptoms coincided with a significant deterioration in mental state after an initial good response to the particular medication. Considering the apparently selective action of the serotonin re-uptake inhibitors, these cases suggest that movement disorders and psychiatric symptoms are unlikely to be due to single neurotransmitter mechanisms and that a disturbance of the balance between the different systems is a more likely hypothesis.