Issues Related to Deep Brain Stimulation for Treatment-Refractory Tourette’s Syndrome

Abstract

Deep brain stimulation (DBS) has been used in a small number of patients with Tourette’s syndrome and results on tics and comorbidities have been promising. The choice of the DBS target appears to influence the effectiveness; preliminary studies and case reports suggest that certain target areas may be more effective than others in patients with specific symptoms and comorbidities. Clinical data on the effect of DBS on tics and behavioral symptoms support its use in patients with severe, refractory Tourette’s syndrome, particularly in younger adults who have a greater severity and prevalence of tics and comorbidities, and are more likely to experience social impairment. Although DBS has shown potential as an ‘add-on’ therapy for Tourette’s syndrome patients failing to show adequate improvement with conventional conservative treatments, several issues remain to be resolved, including patient selection, choice of target, and adverse effects. Successful DBS requires an experienced multidisciplinary team for the management of these complex pre-, peri- and postoperative issues. Future studies should include establishment of consistent inclusion criteria and specific practical requirements for clinical trials, evaluation of the impact of DBS on non-tic symptoms and their influence on outcome, social impairment and quality of life, and the identification of optimum neurophysiologically based DBS targets for improved efficacy in specific patient subtypes.

Long-term Outcome of Globus Pallidus Internus Deep Brain Stimulation in Patients With Tourette Syndrome

“…31 Patient selection for our study was synthesized from criteria used in clinical studies and recommendations from the literature. 5,28,31,36,37 However, severe TS in late adolescence can be disruptive to development, often jeopardizing educational opportunities, and some tics are of sufficient severity to raise concern for self-injury. For these reasons, some of the largest series have included patients as young as 17 or 18 years old, 31,38 and more recently published guidelines concede that there is not yet a consensus among experts.…”

What Patients With Gilles de la Tourette Syndrome Should Be Treated With Deep Brain Stimulation and What Is the Best Target?

“…Measures of tic severity include direct observation of tic frequency using video recordings and clinician-reported rating scales, such as the Yale Global Tic Severity Scale (YGTSS). 67,68,72 Proposed cutoff scores have been published in some guidelines: tic frequency of $1/min 72 ; YGTSS .35/50 (total motor1vocal tic severity score), 67,68,74 with 1 recommendation specifying .15/25 for the motor tic severity score. 68 The other major indication for DBS in GTS is refractoriness to standard treatment.…”

“…67,68,72 Proposed cutoff scores have been published in some guidelines: tic frequency of $1/min 72 ; YGTSS .35/50 (total motor1vocal tic severity score), 67,68,74 with 1 recommendation specifying .15/25 for the motor tic severity score. 68 The other major indication for DBS in GTS is refractoriness to standard treatment. It is imperative to define the concept of "treatment refractoriness" because it appears to differ across research groups, particularly in terms of pharmacotherapies, regime schedules (6 months 67,68 ; 9 months 69 ), and behavioral interventions (considered as an alternative/adjuvant to pharmacotherapy).…”

“…67,69 Some guidelines explicitly specify that treatment approaches such as behavioral techniques require adequate time and compliance to treatment schedules. 68,74 Given that further tic severity and distress may be linked to comorbidities, 18,70 it has been argued that behavioral problems must be targeted as well. 67,68,74 However, the effective treatment of psychiatric comorbidities requires adequate recognition of the full behavioral spectrum of GTS, and this often depends on what specialists have been involved in the multidisciplinary care: neurologists and pediatric neurologists might focus their clinical attention on the motor component of GTS, whereas neuropsychiatrists and child and adolescent psychiatrists are more likely to include a comprehensive assessment of the associated psychiatric comorbidities.…”

“…68,69,72,74 However, in consideration of the phenomenological heterogeneity of tic disorders, 1,3,131 an important question for future research is whether patients with other primary tic disorders and secondary tic disorders (or "tourettisms") should be included as potential candidates for DBS, along with patients who have a validated diagnosis of GTS. 67…”