Stimulation sites in the subthalamic nucleus projected onto a mean 3-D atlas of the thalamus and basal ganglia

Background: In patients with severe forms of Parkinson's disease (PD), deep brain stimulation (DBS) commonly targets the subthalamic nucleus (STN). Recently, the mean 3-D Morel-Atlas of the basal ganglia and the thalamus was introduced. It combines information contained in histological data from ten post-mortem brains. We were interested whether the Morel-Atlas is applicable for the visualization of stimulation sites. Methods: In a consecutive PD patient series, we documented preoperative MRI planning, intraoperative target adjustment based on electrophysiological and neurological testing, and perioperative CT target reconstruction. The localization of the DBS electrodes and the optimal stimulation sites were projected onto the Morel-Atlas. Results: We included 20 patients (median age 62 years). The active contact had mean coordinates Xlat = ±12.1mm, Yap = −1.8mm, Zvert = −3.2mm. There was a significant difference between the initially planned site and the coordinates of the postoperative active contact site (median 2.2mm). The stimulation site was, on average, more anterior and more dorsal. The electrode contact used for optimal stimulation was found within the STN of the atlas in 38/40 (95%) of implantations. Conclusions: The cluster of stimulation sites in individual patients—as deduced from preoperative MR, intraoperative electrophysiology and neurological testing—showed a high degree of congruence with the atlas. The mean 3D Morel Atlas is thus a useful tool for postoperative target visualization. This represents the first clinical evaluation of the recently created atla