The objective of the study was to assess bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) for patients with advanced Parkinson disease (PD).

The study population included 5 patients with bilateral STN DBS who completed a 5-year postoperative follow-up period. In all patients electrodes (Model 3387 or 3389) were stereotactically bilaterally inserted into the STN using a Leksell stereotactic G frame. The clinical rating tests included Unified Parkinson's Disease Rating Scale (UPDRS) and two motor-timed tests derived from CAPIT (rapid movements between two points and stand-walk-sit test). All patients were assessed in off and on condition before implantation and 1, 3 and 5 years in medication on and off condition and stimulation on condition and stimulation off condition. To compare preoperative to postoperative UPDRS scores, only mean values and standard deviations are presented because of the small study population.

The stimulation effect was noted in the off state, resulting in a 59% improvement in motor scores of UPDRS at 5-year follow-up, when compared to preoperative scores. In the on state the stimulation improved motor scores by 17%. At 5-year follow-up, reduction of daily levodopa dose was 50%.

Bilateral STN DBS is an effective and safe treatment for patients with advanced PD. Bilateral STN DBS contributes to improvement of parkinsonian symptoms in the off state and levodopa-induced dyskinesia. This can be correlated with a 50% reduction of daily levodopa dose 5 years postoperatively.