Efficacy of Unilateral Deep Brain Stimulation for Gait Enhancement in Parkinson’s Disease: A Systematic Review and Meta-Analysis

INTRODUCTION: Bilateral electrode implantation is the primary approach for deep brain stimulation (DBS) in Parkinson's disease (PD). However, it may lead to gait deterioration in some patients. This study aimed to investigate the efficacy of unilateral DBS on gait in PD patients as an alternative with fewer side effects and lower costs. METHODS: We systematically searched four major clinical databases to evaluate the effects of unilateral DBS on UPDRS gait score, gait velocity, stride length, cadence, and gait initiation in PD patients. Twenty-three studies were included in the review, selected from an initial pool of 2,415 studies. We also performed a meta-analysis to assess the impact of unilateral DBS on gait velocity and compare its efficacy to bilateral stimulation. The study protocol was registered at PROSPERO with the registration code: CRD42024585359. RESULTS: The included studies assessed gait measures in patients receiving unilateral DBS targeting the STN, globus pallidus internus, pedunculopontine nucleus, and ventral intermediate nucleus. According to the systematic review of clinical evidence, unilateral DBS can improve the UPDRS gait score, freezing of gait, and gait velocity, although to a lesser extent than bilateral stimulation. The meta-analysis revealed a nonsignificant positive pooled effect on gait velocity in the unilateral DBS condition compared to the control condition and no significant difference when compared to bilateral DBS. CONCLUSION: Unilateral DBS shows promise for improving gait in PD, as an alternative with lower costs and side effects, especially in early-stage or asymmetric cases.