gms | German Medical Science

Objective: To review the existing literature and analyze the clinical effects of deep brain stimulation (DBS) for Tourette syndrome (TS). In particular, we aim to evaluate if DBS can effectively reduce symptoms in TS patients and to evaluate if the stimulation of different anatomical targets results in different clinical outcomes.

Methods: We performed a systematic review following the PRISMA guidelines. A search using PubMed was performed to identify all the existing literature on DBS in TS patients. The Yale Global Tic Severity Scale (YGTSS) served as primary outcome measure, while the secondary outcome measures included assessments of obsessive-compulsive (Yale-Brown Obsessive-Compulsive Scale; YBOCS) and affective symptoms (Becks Depression Inventory; BDI). Presurgical and postsurgical scores (T1: ≤ 6 months; T2: ≤ 12 months; T3: >12 months) were compared using a Wilcoxon signed-rank test. For comparison of targets, subgroup analyses were performed using Kruskal-Wallis tests. In case of significant results, post-hoc tests were conducted and Bonferroni-corrected for multiple comparisons.

Results: 65 studies with 376 patients were included in the analysis (n=96 CM-Voi, n=59 CM-Pf, n=100 amGPi and n= 81 pvlGPi. YGTSS scores for all targets combined were significantly reduced at maximum follow-up (p<.001). The majority of patients (69.4%) experienced a significant reduction of at least 50% of their symptoms. Post-hoc tests revealed that median YGTSS scores decreased significantly over time. Regarding the secondary outcome measures, YBOCS and BDI were significantly lower at maximum follow-up for all targets combined (p<.001). Stimulation of all targets (CM-Voi, CM-Pf, amGPi, and pvlGPi) resulted in a significant global YGTSS reduction after up to 12 months (all p<.001). The improvement in YGTSS scores is not the same across the four targets. For instance, tic reduction was significantly smaller for CM-Pf compared to amGPi and pvlGPi, while pvlGPi resulted in significant lager tic reduction rates compared to CM-Voi. Similarly, absolute change scores of the YBOCS at maximum follow-up revealed significant differences between targets.

Conclusion: DBS is a clinically effective therapy option for patients with treatment-refractory TS. All four targets showed slightly different but comparable improvement rates in not only tic-related symptoms as well as comorbid OCD and affective symptoms in TS patients. Moreover, the beneficial effects of DBS seem to increase over time.