Bradykinesia in early and advanced Parkinson's disease

BACKGROUND: Motor impairment in Parkinson's disease (PD) includes slowness (bradykinesia), decreased amplitude (hypokinesia), impaired rhythm and a progressive reduction in speed and amplitude during movement repetition (sequence effect). In the present study we aimed to analyse bradykinesia features in newly-diagnosed and drug-näive patients with PD. Kinematic data were compared with PD patients in the advanced stages of the disease and with healthy controls. We also investigated the effect of selegiline on motor impairment in early PD. METHODS: Fourteen newly-diagnosed and drug-näive PD patients in the early stage of the disease, 11 patients with advanced PD and 20 healthy controls performed a repetitive finger tapping task. Early PD patients were assessed in two separate sessions at baseline and four weeks after treatment with selegiline (10 mg taken daily). The repetitive finger movement was analysed using kinematic techniques. RESULTS: The speed and amplitude of repetitive finger movement were lower in early PD patients than in healthy controls. Early PD patients also had a progressive decrement of movement amplitude (sequence effect). Patients with advanced PD had lower speed, amplitude and movement regularity during finger tapping in comparison to early PD and healthy controls but no sequence effect. In early PD, selegiline improved both the movement speed and amplitude though it did not influence the sequence effect. CONCLUSIONS: The study yields an objective characterization of motor impairment in early and advanced PD. The kinematic assessment of the effects of selegiline on movement abnormalities in early PD provides a better understanding and interpretation of their pathophysiological mechanisms.