Effects of bilateral posteroventral pallidotomy on gait of subjects with Parkinson disease

Background: Most studies documenting the effect of pallidotomy on parkinsonian gait have reported unilateral surgery and used qualitative scales or timed tests that only provide measures of walking speed. Objective: To document the effect of bilateral posteroventral pallidotomy on the walking patterns of patients with Parkinson disease (PD). Design: Case series of gait evaluations performed 1 month before and 1 month after surgery, with antiparkinson medication withheld for 8 hours overnight. Setting: Movement analysis laboratory of a clinical research center Patients: Consecutive sample of 8 men and 3 women with a diagnosis of PD scheduled for bilateral pallidotomy. Intervention: Bilateral posteroventral pallidotomy. Main Outcome Measures: A 3-dimensional motion-capture system allowed calculation of temporal and spatial measurements and joint angular displacements of the lower extremities and trunk during gait. Results: Pallidotomy significantly increased average walking speed from 0.214 statures/s preoperatively to 0.440 statures/s postoperatively (where stature indicates body height) (P = .03). A faster postoperative walking speed was achieved almost exclusively by increasing average stride length from 0.24 to 0.47 statures (P = .03) rather than changing average gait cycle time (1.32 to 1.37 seconds; P = .08). A forward stepwise multiple regression analysis (P<.001) revealed that 96% of the change in stride length postoperatively could be explained by the combination of changes in foot-floor angle, knee, and hip excursion during gait. Conclusions: Bilateral posteroventral pallidotomy was associated with a 2-fold increase in walking speed. Previous studies have demonstrated that walking speed is an important indicator of locomotor performance and level of disability in patients with PD, so the increase in postoperative walking speed likely provided a functional benefit.