Acute effects of bilateral subthalamic nucleus stimulation on clinical and kinematic parameters in Parkinson's disease

After implantation with subthalamic stimulators, nine patients with advanced Parkinson's disease were studied on the task of tracing out, as accurately as possible, the four corners of a square with the dominant hand. The task was performed in four treatment conditions: on stimulation‐off medication, off stimulation‐off medication, off stimulation‐on medication, and on stimulation‐on medication. Movement times and peak velocities improved significantly only in the on stimulation‐on medication condition compared to off stimulation‐off medication. The improvement in clinical parameters with stimulation only (relative to off stimulation off medication) was of borderline significance, while consistent and significant clinical improvement was only obtained with addition of medication (on medication‐on stimulation). This study provides quantitative evidence of the effect of subthalamic stimulation on kinematic measures in Parkinson's disease (PD) and suggests that combined treatment (medication and stimulation) is superior to either treatment alone. © 2001 Movement Disorder Society.