Abstract
Introduction: Current pathophysiological hypotheses of Gilles de la Tourette Syndrome (GTS) refer to temporally abnormal neuronal activation in cortico-striato-thalamo-cortical (CSTC) networks. Modifying cortical activity by non-invasive brain-stimulation appears to be a new treatment option in GTS.Background: Previous studies suggested therapeutic effects of cathodal transcranial direct current stimulation (tDCS) to pre-supplementary motor areas (SMA), however, treatment modalities concerning electrode placement, current intensity and stimulation-rate have not been systematically explored. Aim of this study was to assess efficacy of an alternative stimulation regime on GTS symptoms in a pilot study. To test a treatment protocol with tDCS twice a day, we administered 10 sessions over 5 days of bilateral cathodal tDCS (30 min, 2 mA) over the pre-SMA in three patients with severe GTS. Tic severity as well as obsessive-compulsive (OC) symptoms and affective scales were rated before and after tDCS treatment.Discussion: Only one out of three patients showed a 34.5% reduction in tic severity. The two other patients showed an increase in tic severity. All patients showed a mild increase in positive affect and a reduction in negative affect, OC symptom changes were heterogeneous. Our results do not support earlier findings of extensive therapeutic effects of cathodal tDCS on tics in patients with GTS and show that prediction of stimulation effects on a targeted brain area remains inaccurate.Concluding Remarks: Future research will have to focus on the determination of most effective stimulation modes regarding site, polarity and frequency of tDCS in GTS patients.
Highlights
Current pathophysiological hypotheses of Gilles de la Tourette Syndrome (GTS) refer to temporally abnormal neuronal activation in cortico-striato-thalamo-cortical (CSTC) networks
Repetitive transcranial magnetic stimulation, inducing an electric current in cortical regions via a pulsed magnetic field, has been shown to be efficient in tic reduction when applied at 1 Hz over the supplementary motor area (SMA; Mantovani et al, 2006)
Landeros-Weisenberger et al (2015) presented the first sham controlled double-blind Repetitive transcranial magnetic stimulation (rTMS) study in patients with severe GTS and could not show a significant difference in tic improvement after active rTMS compared to sham rTMS
Summary
Current pathophysiological hypotheses of Gilles de la Tourette Syndrome (GTS) refer to temporally abnormal neuronal activation in cortico-striato-thalamo-cortical (CSTC) networks. Approved pharmacological treatment consists of alpha-2-adreno-receptor-blockers, and distinct antipsychotics Both groups of medications are associated with mild to severe side effects including sedation, cardiovascular dysregulation, extrapyramidal motor symptoms (EPMS), sexual dysfunction, weight gain or cardiac risks that are scarcely tolerated by patients. Depression and anxiety are common co-morbid disorders in adult GTS patients (Evans et al, 2016), and there is an additional need for specific treatment in these domains Psychotherapeutic treatment such as habit reversal training or exposure with response prevention require sufficient adherence while yielding only incomplete remission rates (Capriotti et al, 2014). Results of rTMS in the treatment of GTS are controversial so far (Kious et al, 2016; Pedroarena-Leal and Ruge, 2017) Another emerging NIBS technique, transcranial direct current stimulation (tDCS). Tic severity as well as obsessive-compulsive (OC) symptoms and affective scales were rated before and after tDCS treatment
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