Bilateral Deep Brain Stimulation of the Subthalamic Nucleus or Globus Pallidus Internus Improves Gait Impairment in Parkinson's Disease

Background The effect of deep brain stimulation (DBS) on gait in patients with Parkinson's disease (PD) remains variable, and prospective, long‐term studies, especially involving globus pallidus interna (GPi) stimulation, are limited. Objectives We tested the hypothesis that subthalamic nucleus (STN) and GPi DBS exert acute and chronic effects on gait in patients with PD. Methods Gait kinematics were collected prospectively on patients with PD with bilateral or unilateral STN or GPi DBS, at baseline before initial DBS activation (n = 104), acutely after activation (n = 102), and chronically at 1 month (n = 75) and 12 months (n = 82) OFF‐medications. Gait speed was the main outcome. Kinematic measures of pace, rhythm, and variability and clinical scales were secondary outcomes. Results Average gait speed at baseline was abnormally slow (80.6 cm/s). DBS activation acutely increased gait speed (97.4 cm/s, P < 0.001) which was maintained at 1‐month (93.0 cm/s, P < 0.001) and 12‐month follow‐up (91.2 cm/s, P < 0.001). Acute changes predicted chronic changes. When DBS targets were analyzed separately, only bilateral STN or GPi DBS improved gait speed along with pace, rhythm, and variability. Presurgical levodopa response on the MDS‐UPDRS axial subscore correlated with the response to DBS while the total score did not. Discussion Bilateral STN or GPi DBS should be considered for treatment of gait as both targets improved gait kinematics acutely and chronically. Acute effects of STN or GPi DBS on gait speed should be considered when programming patients as they predict chronic effects. When determining DBS candidacy, the levodopa response on the MDS‐UPDRS axial subscore should be considered.