Gait quality improves after unilateral subthalamic nucleus deep brain stimulation in Parkinson's disease patients

While deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a standard therapy for motor symptoms of Parkinson's disease (PD), its effect on gait is not well established.

This study investigated gait quality in 28 patients with PD undergoing unilateral STN DBS. Gait assessments were performed preoperatively (OFF and ON levodopa) and at two and four months postoperatively using either conventional ring or directional stimulation (OFF levodopa). The primary outcome was the Enhanced Gait Variability Index (EGVI), a measure of gait quality. Patients were stratified into two subgroups based on their baseline OFF-medication EGVI scores: elevated (n = 12) and normative (n = 16). Statistical analysis utilized 2 × 4 repeated measures ANOVA and Pearson correlations.

A significant group-by-visit interaction was observed for EGVI at both comfortable (p < .001) and maximal (p = .014) walking speeds. The elevated variability group demonstrated significant improvement in gait quality from baseline with levodopa and with both ring and directional stimulation. The normative variability group showed no significant change across conditions. No statistically significant difference was found between ring and directional stimulation. Baseline EGVI was strongly correlated with Timed Up and Go performance (r = .75), PIGD score (r = .74), freezing of gait (r = .60), and balance confidence (r = -.55).

Unilateral STN DBS improves gait quality in PD patients with high baseline gait variability and preserves function in those with normal variability. These findings suggest that quantitative gait analysis may aid in patient selection and set therapeutic expectations for DBS.