Abnormal involuntary movements in relation to anticholinergics and levodopa therapy.

During a study comparing levodopa with and without benserazide in Parkinsonism, 19 of 41 patients (42 per cent) receiving concomitant anticholinergic therapy developed abnormal involuntary movements (AIM), in contrast to 11 of 58 patients (19 per cent) receiving only levodopa. This difference is statistically significant. Discontinuation or dose-reduction of anticholinergics in 10 patients without altering the levodopa-dosage resulted in disappearance or amelioration of the AIM in nine cases. The Parkinsonism, however, aggravated subsequently, necessitating resumption of anticholinergics in five cases. These results establich further the facilitating effect of anticholinergics on the emergence of AIM.