Refining the Deep Brain Stimulation Target within the Limbic Globus Pallidus Internus for Tourette Syndrome

Abstract

Background: Deep brain stimulation (DBS) in patients with severe, refractory Tourette syndrome (TS) has demonstrated promising but variable results thus far. The thalamus and anteromedial globus pallidus internus (amGPi) have been the most commonly stimulated sites within the cortico-striato thalamic circuit, but an optimal target is yet to be elucidated. Objectives: This study of 15 patients with long-term amGPi DBS for severe TS investigated whether a specific anatomical site within the amGPi correlated with optimal clinical outcome for the measures of tics, obsessive compulsive behaviour (OCB), and mood. Methods: Validated clinical assessments were used to measure tics, OCB, quality of life, anxiety, and depression before DBS and at the latest follow-up (17-82 months). Electric field simulations were created for each patient using information on electrode location and individual stimulation parameters. A subsequent regression analysis correlated these patient-specific simulations to percentage changes in outcome measures in order to identify any significant voxels related to clinical improvement. Results: A region within the ventral limbic GPi, specifically on the medial medullary lamina in the pallidum at the level of the AC-PC, was significantly associated with improved tics but not mood or OCB outcome. Conclusions: This study adds further support to the application of DBS in a tic-related network, though factors such as patient sample size and clinical heterogeneity remain as limitations and replication is required.

Cellular, molecular, and clinical mechanisms of action of deep brain stimulation—a systematic review on established indications and outlook on future developments

“…The NAcc has also been used to treat different forms of addiction (Müller et al , ). Tourette's syndrome has been treated with DBS in the NAcc (Kuhn et al , ), globus pallidus internus (Akbarian‐Tefaghi et al , ; Fig B), and the ventral anterior thalamus (Voa; Huys et al , ; Fig D). Eating disorders such as anorexia nervosa (CG25; Lipsman et al , ) or morbid obesity (with NAcc and lateral hypothalamic DBS; Whiting et al , ; Tronnier et al , ) have also been investigated as potential indications for DBS therapy.…”

Long‐term effects of anterior pallidal deep brain stimulation for tourette's syndrome

“…Tourette's syndrome (TS) is a disabling chronic neuropsychiatric disorder characterized by motor and vocal tics, associated with behavioral disorders and repercussions on family relationships, social life, and ability to work. Although preliminary findings suggest that deep brain stimulation of the anterior internal pallidum (aGPi‐DBS) may reduce symptoms of severe and refractory forms of TS, long‐term outcomes have not been fully reported . We prospectively followed 16 TS patients treated with aGPi‐DBS for 48 months .…”

Deep brain stimulation for Tourette’s syndrome

“…Additionally, much effort has been put into identifying appropriate targets for DBS. Data from the TAA's DBS Registry and Database have indicated that many different regions/structures located within the cortico-striato-pallido-thalamo-cortical network are promising targets [32].. In the next sections, we discuss some of the most promising DBS targets for TS treatment.…”

“…DBS of the limbic or anteromedial GPi (amGPi) has been successfully applied to TS treatment. In one study, 15 patients with severe and refractory TS were treated with amGPi DBS and clinically assessed before surgery and between 17 and 82 months after surgery [32]. The results showed that the patients' tic severity was significantly reduced at follow-up (mean reduction of YGTSS total score: 38%; phonic score: 38%; motor score: 33%) [32].…”

“…In one study, 15 patients with severe and refractory TS were treated with amGPi DBS and clinically assessed before surgery and between 17 and 82 months after surgery [32]. The results showed that the patients' tic severity was significantly reduced at follow-up (mean reduction of YGTSS total score: 38%; phonic score: 38%; motor score: 33%) [32]. At the group level, amGPi DBS had no significant effect on comorbid OCD (Y-BOCS), depression (BDI), and anxiety (BAI).…”