What patients with Gilles de la Tourette syndrome should be treated with deep brain stimulation and what is the best target?

BACKGROUND: Gilles de la Tourette syndrome (GTS) is a chronic neurodevelopmental disorder characterized by tics and associated behavioral symptoms. Over the past decade, deep brain stimulation (DBS) has been increasingly advocated as a reversible and controllable procedure for selected cases of GTS. OBJECTIVE: We set out to answer 2 clinically relevant questions: what patients with GTS should be treated with DBS and what is the best target? METHODS: We conducted a systematic literature review of the published studies of DBS in GTS and critically evaluated the current evidence for both patient and target selection. RESULTS: Since 1999, up to 99 cases of DBS in GTS have been reported in the scientific literature, with varying selection criteria, stimulation targets, and assessment protocols. The vast majority of studies published to date are case reports or case series reporting successful outcomes in terms of both tic severity improvement and tolerability. The reviewed studies suggest that the best candidates are patients with significant functional impairment related to the tic symptoms, who did not respond to conventional pharmacological and behavioral interventions. The globus pallidus internus and thalamus appear to be the safest and most effective targets, especially for patients with "pure" GTS and patients with comorbid obsessive-compulsive symptoms, anxiety, and depression. CONCLUSION: DBS is a promising treatment option for severe cases of GTS. There is a need to reach consensus on the definition of "treatment-refractoriness" and to conduct larger double-blind randomized controlled studies on the most promising targets.