We examined the effects of
levodopa and unilateral
pallidotomy on quantitative measures of walking and reaching in
Parkinson's disease (PD). We also compared quantitative measures of movement with standard clinical rating scales. We used kinematic measures and the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscale (subscale III) to evaluate the movement of 10 people with PD. Subjects were tested after withholding PD medications for at least 8 hours and again 30 to 45 minutes after taking the first morning dose of
levodopa. They were studied in this manner before unilateral
pallidotomy and then 3.5 to 10 months after surgery. The UPDRS motor subscale was performed in each state. Kinematic data were collected as subjects reached to a target and walked. The UPDRS motor subscale ratings were similar to those reported in the literature:
pallidotomy improved the overall motor score and the contralateral
bradykinesia + rigidity score, but not the gait + posture score. In contrast, kinematic measures demonstrated that
levodopa and
pallidotomy had different effects on walking and reaching speed. Both treatments improved walking speed, and the effect was additive.
Levodopa improved reaching speed before
pallidotomy but did not improve it as much after
pallidotomy. Additionally,
pallidotomy had inconsistent effects on reaching; some subjects were faster and others were slower. The subjects who initially reached more slowly improved after
pallidotomy; the subjects who initially reached more normally (faster) worsened after
pallidotomy. On the basis of our results, we speculate that basal ganglia output pathways that control walking and reaching may be distinct, such that bilateral projections to the pedunculopontine area influence walking, whereas ipsilateral thalamocortical projections influence reaching.