The effect of treatment on eye-head coordination in Parkinson's disease.

Eye-head movements to target steps of amplitude 3.75 degrees to 30 degrees were analyzed in 9 untreated patients with idiopathic Parkinson's disease. Testing was performed before and after the introduction of a dopamimetic drug (L-dopa or bromocriptine) and compared with 9 normal controls. The patients showed a significantly greater scatter of mean head latencies prior to treatment, although their mean latencies were not significantly prolonged. When compared to controls, the patients' head movements were of reduced peak velocity and gain. Treatment resulted in an improvement of gain but not velocity. Analysis of the frequency of gaze types showed no significant effect of treatment.