Effect of RNS in Treatment-refractory Tourette's Syndrome

The study is to investigate the effect of personalized responsive neurostimulation (RNS) therapy guided by stereoelectroencephalography (SEEG) in patients with treatment-resistant Tourette's Syndrome (TR-TS).

Tourette's Syndrome (TS) is a neurodevelopmental disorder characterized by repetitive, involuntary movements and vocalizations known as tics. It typically manifests in childhood and may persist into adulthood. The prevalence of TS varies globally, affecting approximately 1% of the population. There is a broad spectrum of symptom severity. Treatment-refractory TS (TR-TS) refers to cases where standard therapeutic interventions, such as behavioural therapy and medications, have shown limited effectiveness. TR-TS prevalence is relatively lower but highlights the challenges in managing severe and persistent symptoms. In a comprehensive survey of diverse neuromodulation therapies, targeting specific nuclei with personalized responsive neurostimulation (RNS) has the most potential for TR-TS with apparent symptoms. However, the RNS case reports are limited and lack high-quality, evidence-based medical evidence. The stimulation targets of RNS for patients with TS include GPi, amGPi, pvGPi, Cm-Spv-Voi, Cm-Voi, and NA-ALIC. While stereoelectroencephalography (SEEG) brain mapping can help identify Individualized effective targets and stimulation parameters. So, this cohort study focuses on the effectiveness of SEEG-guided RNS on TR-TS patients. Another goal is to study the neuronal activity of the GPi, amGPi, pvGPi, Cm-Spv-Voi, Cm-Voi, and NA-ALIC, or other unreported nuclei targets, respectively. At the same time, some subjects are presented with a task involving an unexpected reward and different cognitive tasks.

Some participants will also be invited to join a related study that involves positron emission tomography (PET) scanning to determine how the stimulation changes activity in the brain. Participation in the separate PET study is optional.

Eligibility Criteria:
Inclusion Criteria:

1. aged 18-65;
2. able to provide written informed consent;
3. have a diagnosis of Tourette's syndrome according to the Statistical Manual of Mental Disorders-Fourth Edition-Text Revised (DSM-IV-TR) criteria and confirmed by the Mini-International Neuropsychiatric Interview Chinese version 5.0;
4. with a YGTSS of at least 35 for at least 12 months before surgery, while YGTSS- Total Motor≥15;
5. must have failed conventional medical treatment at adequate therapeutic doses of three classes of medication lasting for at least three months;
6. must not be suitable for behavioural intervention or that this intervention is inappropriate or unsuccessful;
7. have been on stable comorbid conditions without suicidal ideation for at least six months.

Exclusion Criteria:

1. presence of other psychotic disorders;
2. have a treatment history that includes electroconvulsive therapy (ECT), modified electroconvulsive therapy (MECT), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), DBS, and transcranial magnetic stimulation (TMS);
3. presents a suicide risk (defined as a HAMD-17 score of ≥3 on suicide-related items);
4. experience difficulty in effectively communicating with investigators;
5. with a history of traumatic brain injury (TBI);
6. with intracranial or cardiovascular stents;
7. substance abuse within the past six months;
8. unstable neurological or coagulation disorders;
9. women who are pregnant, lactating, or of childbearing potential who refuse the use of reliable contraception during the study;
10. have been involved in other clinical studies within three months before enrollment in this study;
11. any conditions considered by the study group.