Staged unilateral versus bilateral subthalamic nucleus stimulator implantation in Parkinson disease.

In 17 consecutive patients with Parkinson disease (PD), bilateral subthalamic nucleus (STN) stimulators were implanted during staged surgeries. The Unified Parkinson Disease Rating Scale (UPDRS) and the Dyskinesia Disability Scale were completed both off and on medication prior to any surgery and also OFF and ON stimulation after each surgery. On-medication UPDRS activities of daily living (ADL) and motor examination scores changed little with unilateral or bilateral stimulation. Off-medication UPDRS motor examination scores improved to similar degrees after each staged STN electrode implantation. Most of the improvements in off-medication ADL scores, dyskinesia scores, complications of therapy, and medication dose reduction occurred after unilateral STN stimulation with smaller improvements after the second operation. (c) 2007 Movement Disorder Society.