Results of chronic subthalamic nucleus stimulation for Parkinson's disease: a 1-year follow-up study

Deep brain stimulation (DBS) has been established as an alternative approach for the treatment of advanced Parkinson's disease (PD). Recently, the subthalamic nucleus (STN) has been identified as the optimal target for DBS.

Thirty-eight patients have undergone surgery for advanced PD since 1996. They include 12 females and 26 males with a mean age of 55.6 years. The mean stage on the Hoehn and Yahr Scale was 3.5 (off condition). Electrodes (Medtronic DBS 31389) were stereotactically implanted into the STN bilaterally. Targeting was performed using computerized tomography (CT) scans and ventriculography (VG). After 4 days of external stimulation, permanent neurostimulators were implanted. Patients were evaluated preoperatively and 1, 6, and 12 months postoperatively. Evaluations were performed in defined on and off states using the Unified Parkinson's Disease Rating Scale (UPDRS) as well as the Hoehn and Yahr Scale, the dyskinesia scale, and the Activities of Daily Living (ADL) Scale.

Significant improvement of all motor symptoms was found in all patients (UPDRS motor score 32/48 preoperatively versus 15/30 at 12-month follow-up, p < 0.001). Daily off-times were reduced by 35%. Dyskinesias also improved markedly (UPDRS IV: 3.2/3.1 [on/off] vs. 0.9/1.3 at 12 months follow-up). Postoperative L-dopa medication was adjusted (mean reduction: 53%). Complications occurred in two patients (5%) who developed infections, leading to system removal. Systems were replaced after 6 months. Two patients (5%) had a permanent worsening of a previously known depressive state and developed progressive dementia.

TN stimulation is a relatively safe procedure for treating advanced PD. The possibility of readjusting the stimulation parameters postoperatively improves the therapeutic outcome and reduces side effects in comparison to ablative methods.