Neuroanatomical Considerations for Optimizing Thalamic Deep Brain Stimulation in Tourette Syndrome

Background: Deep brain stimulation (DBS) of the centromedian (CM) thalamic nucleus has reportedly been used to treat severe Tourette syndrome (TS) with promising outcomes; however, it remains unclear how DBS electrode position and stimulation parameters modulate the specific area and related networks. We aimed to evaluate the relationships between the anatomical location of stimulation fields and clinical responses including therapeutic and side effects. Methods: We collected data from eight TS patients treated with DBS. We evaluated the clinical outcomes using Yale Global Tic Severity Scale (YGTSS), Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and Hamilton Depression Rating Scale (HAM-D). The DBS lead location was evaluated in the normalised brain space using a 3-D atlas. The volume of tissue activated (VTA) was determined, and the associated normative connective analyses were performed to link the stimulation field with the therapeutic and side effects. Results: The mean follow-up period was 10.9 {+/-} 3.9 months. All clinical scale showed significant significant improvement. While the VTA associated with therapeutic effects covers the CM and ventrolateral nuclei and showed association with motor networks, those associated with paraesthesia and dizziness were associated with stimulation of the ventralis caudalis and red nucleus, respectively. Depressed mood was associated with the spread of stimulation current to the mediodorsal nucleus and showed association with limbic networks. Conclusion: Our study addresses the importance of accurate implantation of DBS electrodes for obtaining standardised clinical outcomes and suggests that meticulous programming with careful monitoring of clinical symptoms may improve outcomes.