DBS in Parkinson Disease: Precision of Targeting Assessed in a Mean Three-Dimensional Atlas of the Thalamus and Basal Ganglia

Aim: Deep brain stimulation (DBS) has been established as an invasive therapy of treatment of severe forms of movement disorders such as Parkinson disease (PD). Most patients with PD are treated by DBS in the area of the subthalamic nucleus (STN). However, the exact location of the optimal target site and the optimal targeting procedures are still debated.

Methods: In a consecutive PD patient series (2010 to 2011) we documented preoperative magnetic resonance imaging planning, intraoperative target adjustment, and postoperative computed tomographic (CT) target reconstruction. The localizations of the DBS electrodes were projected onto the mean three-dimensional Morel’s atlas of the basal ganglia and the thalamus.

Results: We included 20 patients (12 men, median age 62 years; 40 implantations). The active contact had median coordinates X_lat = ±12.0, Y_ap = −1.8, Z_vert = −2.8 mm. Of the implanted electrodes, 90% were in contact with the STN of the atlas. Median penetration into STN was 6 mm. There was a significant difference between the initially planned site and the coordinates of the active (median 2.2 mm). The stimulation site was, on average, more anterior and more dorsal.

The optimal stimulation site was within STN in 76% and within 2 mm of STN in 100% of penetrations.

Conclusions: The variability between the individual anatomical STN configurations is sufficiently small to permit the application of the averaged atlas.

The deviation between preoperative planning and postoperative CT reconstruction demonstrates the importance of intraoperative recording of neuronal activity and clinical testing of stimulation efficiency.

Among all anatomical structures, stimulation sites within the STN proper were most efficient in improving clinical outcome.