Objective: We performed a retrospective analysis of Tourette syndrome (TS) patients receiving deep brain stimulation (DBS) therapy as part of the Tourette Association of America International registry. The analysis focused on the assessment of active DBS contact locations and their correlation to clinical response.

Background: DBS can be beneficial for select cases of severe, treatment-refractory TS. The most common DBS targets for TS are centromedian (CM) thalamus and anterior and posterior globus pallidus internus (GPi). Responses to DBS vary significantly across patients and centers. Reliable predictors of response and the most effective brain regions to target with DBS for TS are currently unknown.

Methods: Structural imaging and clinical outcomes of TS DBS patients were collected in collaboration with the registry and database. TS severity was measured at baseline and several time points post-DBS using the Yale Global Tic Severity Scale (YGTSS). DBS contacts were localized in patients with imaging that met inclusion criteria. An MRI cohort atlas was used to compare contact locations across patients. The criteria for response was set at 30% reduction in YGTSS total score. Kaplan-Meier (KM) survival analysis was used to determine the median time to response. A log-rank test was used to compare KM curves for patients implanted in CM versus GPi.

Results: The clinical outcomes analysis included 109 TS DBS patients. There were 68 patients included in the imaging analysis. The mean YGTSS total scores decreased over time compared to baseline (Fig. 1). The median time to response was 9 months (Fig. 2). KM curves did not differ for patients implanted in CM versus GPi (Fig. 3). The preliminary imaging analysis showed that active contact locations alone do not predict clinical response (Fig. 4), however volumes of tissue activation (VTAs) were not used. [figure1][figure2][figure3][figure4]

Conclusions: We used a unique dataset of a large cohort of TS DBS patients to assess targets and contact locations with respect to outcome. DBS produced beneficial effects in the majority of TS patients in the cohort. Response to DBS for TS had a relatively long time constant and there may be many factors underpinning this delay. We plan to incorporate VTAs into our imaging analysis to assess stimulation regions, as the effects of TS DBS may depend on stimulation parameters and modulation of specific fiber tracts or functional networks.

References: 1. Martinez-Ramirez D, Jimenez-Shahed J, Leckman JF, Porta M, Servello D, Meng F, Kuhn J, Huys D, Baldermann JC, Foltynie T, Hariz MI, Joyce EM, Zrinzo L, Kefalopoulou Z, Silburn P, Coyne T, Mogilner AY, Pourfar MH, Khandhar SM, Auyeung M, Ostrem JL, Visser-Vandewalle V, Welter M, Mallet L, Karachi C, Houeto JL, Klassen BT, Ackermans L, Kaido T, Temel Y, Gross RE, Walker HC, Lozano AM, Walter BL, Mari Z, Anderson WS, Changizi BK, Moro E, Zauber SE, Schrock LE, Zhang J, Hu W, Rizer K, Monari EH, Foote KD, Malaty IA, Deeb W, Gunduz A, Okun MS. Efficacy and Safety of Deep Brain Stimulation in Tourette SyndromeThe International Tourette Syndrome Deep Brain Stimulation Public Database and Registry. JAMA Neurol. 2018;75(3):353–359. doi:10.1001/jamaneurol.2017.4317

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MDS Abstracts - https://www.mdsabstracts.org/abstract/imaging-analysis-of-the-international-tourette-syndrome-deep-brain-stimulation-registry-and-database/