Target-Specific Effects of Deep Brain Stimulation for Tourette Syndrome: A Systematic Review and Meta-Analysis

Abstract

Background: Extended research has pointed to the efficacy of deep brain stimulation (DBS) in treatment of patients with treatment-refractory Tourette syndrome (TS). The four most commonly used DBS targets for TS include the centromedian nucleus–nucleus ventrooralis internus (CM-Voi) and the centromedian nucleus–parafascicular (CM-Pf) complexes of the thalamus, and the posteroventrolateral (pvIGPi) and the anteromedial portion of the globus pallidus internus (amGPi). Differences and commonalities between those targets need to be compared systematically.Objective: Therefore, we evaluated whether DBS is effective in reducing TS symptoms and target-specific differences.Methods: A PubMed literature search was conducted according to the PRISMA guidelines. Eligible literature was used to conduct a systematic review and meta-analysis.Results: In total, 65 studies with 376 patients were included. Overall, Yale Global Tic Severity Scale (YGTSS) scores were reduced by more than 50 in 69% of the patients. DBS also resulted in significant reductions of secondary outcome measures, including the total YGTSS, modified Rush Video-Based Tic Rating Scale (mRVRS), Yale-Brown Obsessive Compulsive Scale (YBOCS), and Becks Depression Inventory (BDI). All targets resulted in significant reductions of YGTSS scores and, with the exception of the CM-Pf, also in reduced YBOCS scores. Interestingly, DBS of pallidal targets showed increased YGTSS and YBOCS reductions compared to thalamic targets. Also, the meta-analysis including six randomized controlled and double-blinded trials demonstrated clinical efficacy of DBS for TS, that remained significant for GPi but not thalamic stimulation in two separate meta-analyses.Conclusion: We conclude that DBS is a clinically effective treatment option for patients with treatment-refractory TS, with all targets showing comparable improvement rates. Future research might focus on personalized and symptom-specific target selection.

Microlesion Effect Induced by Electrode Implantation in the Posteroventral Globus Pallidus Interna for Severe Dystonic Tics

“…The most common target in TS with dystonic tics is the thalamic centromedian-parafascicular (CM-pf) complex [6]. Stimulation of the anteromedial GPi has resulted in slightly but non-significantly higher improvement rates compared with thalamic DBS followed by the pvlGPi [10,11]. In our case, the blepharospasm and other severe symptoms of TS have improved after bilateral pvlGPi DBS.…”

“…DBS is, therefore, a potential treatment reserved for patients with severe TS that has been refractory to medical treatment [3,[7][8][9][10]. Although the pathophysiology of tics is not fully understood, it is thought that tics are due to dysfunction in the basal ganglia-thalamo-cortical loops, which can be favourably modified by DBS [11,12]. Concerning the DBS target, no significant differences between targets have been detected according to the International Deep Brain Stimulation Database and Registry [4], and the recent European guidelines recommended no specific target [4].…”

Proceedings of the 10th annual deep brain stimulation think tank: Advances in cutting edge technologies, artificial intelligence, neuromodulation, neuroethics, interventional psychiatry, and women in neuromodulation

“…Since that time, the potential of this treatment has been further explored for other psychiatric indications in otherwise treatment resistant patients. A current meta-analysis conducted by Wehmeyer et al (2021) summarized the results of studies with DBS in GTS and demonstrated that chronic DBS with different targets was associated with significant tic-reduction, with pallidal stimulation in this paper showing a possible advantage. Connectivity studies facilitated a more individualized approach for GTS patients with different symptoms and different comorbidities.…”

Tourettic OCD: Current understanding and treatment challenges of a unique endophenotype

“…Four targets within the basal ganglia have been most commonly used: the centromedian nucleus–nucleus ventrooralis internus complex of the thalamus (CM-Voi), the centromedian nucleus–parafascicular (CM-Pf) complex of the thalamus, the posteroventrolateral (pvIGPi), and the anteromedial portion of the globus pallidus internus (amGPi). A recent review on DBS in TS ( 63 ) analyzed 65 studies and included 376 patients. Overall, nearly 70% of the patients had >50 reduction on Yale Global Tic Severity Scale (YGTSS) scores regardless of these different targets.…”