Asymmetry in clinical features of drug-induced parkinsonism.

In clinical practice, distinguishing drug-induced parkinsonism from Parkinson's disease may be difficult. Asymmetry is generally not felt to be common in drug-induced parkinsonism. The authors investigated asymmetry of signs and symptoms in 20 patients with drug-induced parkinsonism. Tremor was identified in seven patients, slowness in five, and mixed symptoms in eight. A notable asymmetry of signs was seen in six patients. As in Parkinson's disease, subgroups seem to exist within the group of patients with drug-induced parkinsonism, and an asymmetry of signs and symptoms is not uncommon.