Defining Targets for Tic Detection and Suppression in Tourette Syndrome Deep Brain Stimulation

PROJECT SUMMARY Tourette syndrome (TS) is a continuous lifelong condition that is highly prevalent, socially disabling, and in some severe cases, physically injurious. DBS has emerged as a promising treatment option for addressing uncontrollable tics in medically resistant and severe cases of TS frequently involving self-injurious behavior. We have undertaken a major informatics initiative by establishing the International TS DBS Registry and Database, a multi-country consortium that has captured long term outcomes of 277 TS DBS patients representing 50-75% of all TS DBS cases worldwide. From these outcomes, two deep brain targets have emerged as potentially effective: the centromedian nucleus region (CM) of the thalamus, and the anterior globus pallidus internus (aGPi). However, our current understanding of tic generation is limited by many factors including a lack of animal models for TS, apparently normal brain structure on structural imaging, and the impracticality of studying involuntary motor tics with functional imaging. Next generation closed-loop DBS systems can record brain activity in patients with TS and identify the neurophysiological correlates of tics. Moreover, these devices can deliver stimulation in response to a patient's symptomatic state. Our overall goal is to develop neurophysiology driven and connectivity-guided closed-loop DBS systems for the improved treatment of TS. To this end, we will implant 8 medically resistant TS patients with bilateral leads in the CM and aGPi. In Aim 1, we will identify structural network projections from CM and aGPi to guide pre-operative surgical planning and post-operative selection of stimulation parameters. In Aim 2, we will identify neurophysiologic correlates of tic genesis in the CM and aGPi. We will also study thalamo-pallidal network interactions leading to and during tics. In Aim 3, we will test the feasibility, safety, and efficacy of closed-loop TS DBS. We expect that closed-loop stimulation will provide more effective and personalized treatment options with longer battery life and fewer adverse effects.