Deep brain stimulation of the thalamus as a treatment of intractable Tourette Syndrome

Gilles de la Tourette Syndrome (TS) is a chronic neuropsychiatric disorder characterised by multiple motor tics and one or more phonic (vocal) tics. 90% of patients have comorbid disorders including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), self-injurious behaviours, depression and anxiety. Treatment of TS includes typical and atypical neuroleptics, alpha-adrenergic agonists, benzo-diazepines and behavioural interventions. Recently, a number of case reports and case series have demonstrated that deep brain stimulation (DBS) targeting the centromedian-parafascicular complex (CM-PF) of the thalamus, globus pallidus or internal capsule and nucleus accumbens may have beneficial effects on TS. The best evidence currently exists for the safety and efficacy of DBS targeted to the thalamus. Here, we report on the efficacious treatment of a 30 year old man with a 15 years history of medication resistant TS with a predominant complex, self-injurious motor tic of violent pounding his chin with the left hand (YGTSS 77/100), comorbid OCD (Y-BOCS 24/40) and moderate depression (HAM-D: 28) in bipolar disorder with bilateral DBS placed within the thalamus. Neuropsychological testing and positron emission tomography (PET) were performed before and after the start of treatment. Following the guidelines on DBS for neuropsychiatric disorders and the recent recommendations for DBS in TS, the local DBS-assessment committee ensured that all suggested medical, neurological and psychiatric criteria were met. After local ethics committee approval and written informed consent, two DBS electrodes were placed in the CM-PF complex of the thalamus under general anaesthesia.

Postoperatively, the tics completely disappeared but reoccurred in a mild form after three days. First stimulation one week after surgery yielded an immediate effect with suppression of the contralateral tics, respectively. Treatment was started on the right hemisphere (most distal electrode, 4V, 130Hz, 60µs) leading to a complete suppression of the most disabling left sided complex motor tic. One week later, the most distal electrode on the left side was activated (5V, 130Hz, 60µs) followed by a reduction of the contralateral motor tics. Tics remained markedly reduced until the most recent evaluation seven weeks after surgery (YGTSS 29 [63%]). Symptoms of OCD disappeared completely after initial stimulation. Depressive symptoms showed a delayed remission after 7 weeks (HAM-D: 9). No side effects were reported within these stimulation parameters. This observation of an effective treatment of TS with predominantly motor tics along with the comorbid symptoms of OCD and depression adds to the increasing body of evidence indicating that DBS of the medial thalamus is a safe and efficacious treatment option for otherwise therapy resistant severe cases of TS. Controlled clinical trials are under way to further evaluate the efficacy and safety of DBS treatment of TS.