Bilateral subthalamic stimulation for Parkinson's disease by using three-dimensional stereotactic magnetic resonance imaging and electrophysiologicalguidance

Object. Several methods are used for stereotactically guided implantation o f electrodes into the subthalamic nucleus (STN) for continuous high-frequen cy stimulation in the treatment of Parkinson's disease (PD). The authors pr esent a stereotactic magnetic resonance (MR) method relying on three-dimens ional (3D) T-1-weighted images for surgical planning and multiplanar T-2-we ighted images for direct visualization of the STN, coupled with electrophys iological recording and stimulation guidance. Methods. Twelve patients with advanced PD were enrolled in this study of bi lateral STN implantation. Both STNs were visible as 3D ovoid biconvex hypoi ntense structures located in the upper mesencephalon. The coordinates of th e centers of the STNs were determined with reference to the patient's anter ior commissure-posterior com missure line by using a new landmark, the ante rior border of the red nucleus. Electrophysiological monitoring through fiv e parallel tracks was performed simultaneously to define the functional tar get accurately. Microelectrode recording identified high-frequency, spontaneous, movement-r elated activity and tremor-related cells within the STNs. Acute STN macrost imulation improved contralateral rigidity and akinesia, suppressed tremor w hen present, and could induce dyskinesias. The central track, which was dir ected at the predetermined target by using MR imaging, was selected for imp lantation of 19 of 24 electrodes. No surgical complications were noted. Conclusions. At evaluation 6 months after surgery, continuous STN stimulati on was shown to have improved parkinsonian motor disability by 64% and 78% in the "off" and "on" medication states, respectively. Antiparkinsonian dru g treatment was reduced by 70% in 10 patients and withdrawn in two patients . The severity of levodopa induced dyskinesias was reduced by 83% and motor fluctuations by 88%. Continuous high-frequency stimulation of the STN appl ied through electrodes implanted with the aid of 3D MR imaging and electrop hysiological guidance is a safe and effective therapy for patients sufferin g from severe, advanced levodopa-responsive PD.