Comparative effects of unilateral and bilateral subthalamic nucleus deep brain stimulation on gait kinematics in Parkinson's disease: a randomized, blinded study.

Abstract

Gait dysfunction in Parkinson's disease (PD) does not always respond to bilateral subthalamic nucleus deep brain stimulation (STN-DBS). Since right hemisphere motor networks may be dominant for gait control, identical stimulation of asymmetric circuits could account for gait dysfunction. We compared the effects of bilateral and unilateral STN-DBS on gait kinematics in PD patients who developed gait impairment after STN-DBS. Twenty-two PD patients with >50% improvement in motor scores, but dopamine-resistant gait dysfunction 6-12months after bilateral STN-DBS were blindly tested off dopaminergic effects in four randomly assigned DBS conditions: bilateral, right-sided, left-sided and off stimulation. Motor scores (MDS-UPDRS III), gait scores (MDS-UPRDS 2.11-2.13+3.9-3.13), turning time (seconds), stride length (meters) and velocity (meters/second) were measured 1h after DBS changes. Motor and gait scores significantly improved with bilateral versus unilateral STN-DBS. Stride length and velocity (0.95±0.06, 0.84±0.07) significantly improved with bilateral (1.09±0.04, 0.95±0.05), right-sided (1.06±0.04, 0.92±0.05) and left-sided stimulation (1.01±0.05, 0.90±0.05) (p<0.05). Stride length significantly improved with right-sided versus left-sided (0.05±0.02) and bilateral versus left-sided stimulation (0.07±0.02) (p<0.05). Turning time (4.89±0.6) tended to improve with bilateral (4.13±0.5) (p=0.15) and right-sided (4.27±0.6) (p=0.2) more than with left STN-DBS (4.69±0.5) (p=0.5). Bilateral STN-DBS yields greater improvement in motor and gait scores in PD patients. Yet, unilateral stimulation has similar effects on gait kinematics. Particularly, right-sided stimulation might produce slightly greater improvements. Although the clinical relevance of differential programming of right versus left-sided STN-DBS is unclear, this approach could be considered in the management of treatment-resistant gait dysfunction in PD.