Object: Bilateral subthalamic nucleus (STN) stimulation is increasingly used in patients with advanced Parkinson disease (PD). This study was performed to evaluate the long-term efficacy and safety of bilateral STN stimulation in cases of PD.
Methods: The authors performed a prospective, open-label study in patients with PD who underwent bilateral STN stimulation. The authors compared motor scores and activities of daily living (ADL) scores based on the Unified PD Rating Scale (UPDRS) obtained before surgery while patients were in the medication-off state with scores obtained at follow-up evaluations of these patients while in the medication-off/stimulator-on state. Data contained in patient diaries were also compared. Thirty-three patients with PD were evaluated 12 months postoperatively and 19 were evaluated at a mean follow-up time of 28 months. A comparison between UPDRS scores obtained in patients in the medication-off/stimulator-on state and those obtained when patients were in the baseline medication-off state showed a 27% improvement in ADL scores and a 28% improvement in motor scores after surgery. There was a 57% reduction in the use of levodopa-equivalent medication doses. The percentage of the waking day that patients were in the medication-on state increased from 38 to 72%. Surgical complications included seizures (three patients), confusion (five patients), hemiballismus (one patient), and visual disturbance (one patient). Stimulation-related adverse effects were mild. Device-related events included nine lead replacements, seven lead revisions, six extension replacements, and 12 implantable pulse generator (IPG) replacements; one IPG was cleaned and one IPG was placed in a pocket because of the presence of a shunt.
Conclusions: Bilateral STN simulation is associated with a significant improvement in the motor features of PD. Device-related events were common in the first 20 patients who underwent surgery, often requiring repeated surgeries.