Thalamic Connectivity Patterns with Subthalamic Nucleus Deep Brain Stimulation (P1.001)

Objective: To characterize stimulator-thalamic connectivity profiles in Parkinson Disease (PD) patients undergoing STN-DBS therapy. Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for PD. Although the mechanism of action remains unclear, the modulation of white matter structures in proximity to the STN and with projections into the thalamus has been suggested. Using tractography, we have previously demonstrated that clinically beneficial electrodes have larger connectivity to the thalamus, compared to less effective electrodes. Here, we report on the specific thalamic nuclei stimulated by STN-DBS. Methods: Twenty-two patients with idiopathic PD (11 females, age 57.4±9.2 years, disease duration 13.4±6.4 years) who received bilateral STN DBS at the National Institutes of Health were included. All patients received preoperative and postoperative MRI and CT scans, including diffusion-tensor imaging. Image co-registrations were performed in patient-specific space to allow proper registration and accurate electrode localization using DBSproc. The volume of tissue activated (VTA) for each electrode was estimated based on stimulation parameters and used as seed for tracking. Thalamic nuclei ROIs were mapped from the Talairach-Tournoux atlas to patient-specific space. Connectivity between VTA and each thalamic nucleus was assessed using probabilistic tractography for the stimulating contact. Results: All patients demonstrated significant benefits, as illustrated by the UPDRS-IV after 3 months (preoperative 8.8±3.7, postoperative 3.2±1.8, p<0.0001). Connectivity of VTA of all stimulating contacts showed tracts reaching the motor nuclei of the thalamus for 97[percnt] of the contacts, with 94[percnt] reaching ventrolateral nucleus and 88[percnt] reaching ventroanterior nucleus. Conclusions: Our data suggests that the modulation of the motor nuclei of the thalamus is implicated in the mechanism of action of STN-DBS, in agreement with previous electrophysiological and PET studies. This adds to our previously published data on DTI imaging as a tool for understanding and guiding DBS therapy. Disclosure: Dr. Huang has nothing to disclose. Dr. Vanegas-Arroyave has nothing to disclose. Dr. Ahmad has nothing to disclose. Dr. Zaghloul has nothing to disclose. Dr. Hallett has nothing to disclose. Dr. Horovitz has nothing to disclose. Dr. Lungu has nothing to disclose.