Deep Brain Stimulation in Tourette's Syndrome

Bilateral Globus Pallidus Externus Deep Brain Stimulation for the Treatment of Refractory Tourette Syndrome: An Open Clinical Trial

OBJECTIVES

We have previously proposed that Tourette syndrome (TS) is the clinical expression of the hyperactivity of globus pallidus externus (GPe) and various cortical areas. This study was designed to test this hypothesis by verifying the efficacy and safety of bilateral GPe deep brain stimulation (DBS) for treating refractory TS.

MATERIALS AND METHODS

In this open clinical trial, 13 patients were operated on. Target coordinates (center of GPe) were obtained by direct visualization. Physiological mapping was performed with macrostimulation and microrecording. Primary and secondary outcome measures were, respectively, responder and improvement rates of TS and comorbidities, according to pre- and postoperative scores on the following assessment instruments: Yale Global Tic Severity Scale, Yale-Brown Obsessive Compulsive Scale, Beck Depression Inventory/Hamilton Depression Rating Scale, Beck Anxiety Inventory/Hamilton Anxiety Rating Scale, and Concentrated Attention test.

RESULTS

Intraoperative stimulation (100 Hz/5.0V) did not produce any adverse effects or impact on tics. Microrecording revealed bursting cells discharging synchronously with tics in the central part of the dorsal half of GPe. Patients were followed up for a mean of 61.46±48.50 months. Responder rates were 76.9%, 75%, 71.4%, 71.4%, and 85.7%, respectively, for TS, obsessive-compulsive disorder (OCD), depression, anxiety, and attention deficit hyperactivity disorder. Mean improvements among responders in TS, OCD, depression, and anxiety were 77.4%, 74.7%, 89%, and 84.8%, respectively. After starting stimulation, tic improvement was usually delayed, taking up to ten days to manifest. Afterward, it increased over time, usually reaching its maximum at approximately one year postoperatively. The best stimulation parameters were 2.3V to 3.0V, 90 to 120 μsec, and 100 to 150 Hz, and the most effective contacts were the two dorsal ones. Two complications were registered: reversible impairment of previous depression and transient unilateral bradykinesia.

CONCLUSIONS

Bilateral GPe-DBS proved to be low risk and quite effective for treating TS and comorbidities, ratifying the pathophysiological hypothesis that led to this study. Moreover, it compared favorably with DBS of other targets currently in use.

Comparison of children and adults in deep brain stimulation for Tourette Syndrome: a large-scale multicenter study of 102 cases with long-term follow-up

BACKGROUND

Deep brain stimulation (DBS) is a promising therapy for refractory Gilles de la Tourette syndrome (GTS). However, its long-term efficacy, safety, and recommended surgical age remain controversial, requiring evidence to compare different age categories.

METHODS

This retrospective cohort study recruited 102 GTS patients who underwent DBS between October 2006 and April 2022 at two national centers. Patients were divided into two age categories: children (aged < 18 years; n = 34) and adults (aged ≥ 18 years; n = 68). The longitudinal outcomes as tic symptoms were assessed by the YGTSS, and the YBOCS, BDI, and GTS-QOL were evaluated for symptoms of obsessive-compulsive disorder (OCD), depression, and quality of life, respectively.

RESULTS

Overall, these included patients who finished a median 60-month follow-up, with no significant difference between children and adults (p = 0.44). Overall, the YGTSS total score showed significant postoperative improvements and further improved with time (improved 45.2%, 51.6%, 55.5%, 55.6%, 57.8%, 61.4% after 6, 12, 24, 36, 48, and ≥ 60 months of follow-up compared to baseline, respectively) in all included patients (all p < 0.05). A significantly higher improvement was revealed in children than adults at ≥ 60 months of follow-up in the YGTSS scores (70.1% vs 55.9%, p = 0.043), and the time to achieve 60% improvement was significantly shorter in the children group (median 6 months vs 12 months, p = 0.013). At the last follow-up, the mean improvements were 45.4%, 48.9%, and 55.9% and 40.3%, 45.4%, and 47.9% in YBOCS, BDI, and GTS-QOL scores for children and adults, respectively, which all significantly improved compared to baseline (all p < 0.05) but without significant differences between these two groups (all p > 0.05), and the children group received significantly higher improvement in GTS-QOL scores than adults (55.9% vs. 47.9%, p = 0.049).

CONCLUSIONS

DBS showed acceptable long-term efficacy and safety for both children and adults with GTS. Surgeries performed for patients younger than 18 years seemed to show acceptable long-term efficacy and safety and were not associated with increased risks of loss of benefit compared to patients older than 18 at the time of surgery. However, surgeries for children should also be performed cautiously to ensure their refractoriness and safety.

Stereotactic Surgery for Treating Intractable Tourette Syndrome: A Single-Center Pilot Study

To evaluate the potential effect of radiofrequency ablation and deep brain stimulation in patients with treatment-refractory Tourette syndrome (TS), this study enrolled thirteen patients with TS who were admitted to our hospital between August 2002 and September 2018. Four patients received a single- or multi-target radiofrequency ablation after local, potentiated, or general anesthesia; eight patients underwent deep brain stimulation (DBS) surgery; and one patient underwent both ablation and DBS surgery. The severity of tics and obsessive compulsive disorder symptoms and the quality of life were evaluated using the Yale Global Tic Severity Scale (YGTSS), Yale−Brown Obsessive Compulsive Scale (YBOCS), and Gilles de la Tourette Syndrome Quality of Life scale (GTS-QOL), respectively, before surgery, one month after surgery, and at the final follow-up after surgery, which was conducted in December 2018. A paired-sample t test and a multiple linear regression analysis were performed to analyze the data. All patients underwent the operation successfully without any severe complications. Overall, the YGTSS total scores at one month post-surgery (44.1 ± 22.3) and at the final visit (35.1 ± 23.7) were significantly decreased compared with those at baseline (75.1 ± 6.2; both p < 0.05). Additionally, the YBOCS scores at one month post-surgery (16.5 ± 10.1) and at the final visit (12.0 ± 9.5) were significantly decreased compared with those at baseline (22.5 ± 13.1; both p < 0.05). Furthermore, the GTS-QOL scores at one month post-surgery (44.0 ± 12.8) and at the final visit (31.0 ± 17.8) were significantly decreased compared with those at baseline (58.4 ± 14.2; both p < 0.05). Results from a multiple linear regression analysis revealed that the improvement in the YGTSS total score was independently associated with the improvement in the GTS-QOL score at one month post-surgery (standardized β = 0.716, p = 0.023) and at the final visit (standardized β = 1.064, p = 0.000). Conversely, changes in YBOCS scores did not correlate with changes in GTS-QOL scores (p > 0.05). Our results demonstrate that tics, psychiatric symptoms, and the quality of life in patients with intractable TS may be relieved by stereotactic ablation surgery and deep brain stimulation. Furthermore, it appears that the improvement in tics contributes more to the post-operative quality of life of patients than does the improvement in obsessive compulsive symptoms.

Pre-Clinical Development of Robot-Assisted Ventriculoscopy for 3D Image Reconstruction and Guidance of Deep Brain Neurosurgery

Conventional neuro-navigation can be challenged in targeting deep brain structures via transventricular neuroendoscopy due to unresolved geometric error following soft-tissue deformation. Current robot-assisted endoscopy techniques are fairly limited, primarily serving to planned trajectories and provide a stable scope holder. We report the implementation of a robot-assisted ventriculoscopy (RAV) system for 3D reconstruction, registration, and augmentation of the neuroendoscopic scene with intraoperative imaging, enabling guidance even in the presence of tissue deformation and providing visualization of structures beyond the endoscopic field-of-view. Phantom studies were performed to quantitatively evaluate image sampling requirements, registration accuracy, and computational runtime for two reconstruction methods and a variety of clinically relevant ventriculoscope trajectories. A median target registration error of 1.2 mm was achieved with an update rate of 2.34 frames per second, validating the RAV concept and motivating translation to future clinical studies.

Enriched Environment Facilitates Anxiolytic Efficacy Driven by Deep-Brain Stimulation of Medial Prefrontal Cortex

Deep brain stimulation (DBS) is a widely used treatment for neurodegenerative disorders like Parkinson’s disease. Recently, several studies have used preclinical animal models to suggest that DBS has a potential to improve emotional symptoms in mental disorders such as treatment-resistant depression and post-traumatic stress disorder. An important difference between neurodegenerative and emotional disorders is the crucial role of environment in the ontogeny of the latter. Thus, it is important to understand the effects of DBS in the context of environmental variation. In this study, we show that DBS of ventromedial prefrontal cortex reduces anxiety in rats when it is coupled with simultaneous exposure to an enriched environment (EE). In contrast, effects of DBS on anxiety-like behaviors remained equivocal when animals were housed in standard laboratory conditions. These results suggest that the ability of DBS to treat anxiety and related phenotypes can be significantly enhanced by EE opportunities.

Non-invasive modulation reduces repetitive behavior in a rat model through the sensorimotor cortico-striatal circuit

Involuntary movements as seen in repetitive disorders such as Tourette Syndrome (TS) results from cortical hyperexcitability that arise due to striato-thalamo-cortical circuit (STC) imbalance. Transcranial direct current stimulation (tDCS) is a stimulation procedure that changes cortical excitability, yet its relevance in repetitive disorders such as TS remains largely unexplored. Here, we employed the dopamine transporter-overexpressing (DAT-tg) rat model to investigate behavioral and neurobiological effects of frontal tDCS. The outcome of tDCS was pathology dependent, as anodal tDCS decreased repetitive behavior in the DAT-tg rats yet increased it in wild-type (wt) rats. Extensive deep brain stimulation (DBS) application and computational modeling assigned the response in DAT-tg rats to the sensorimotor pathway. Neurobiological assessment revealed cortical activity changes and increase in striatal inhibitory properties in the DAT-tg rats. Our findings show that tDCS reduces repetitive behavior in the DAT-tg rat through modulation of the sensorimotor STC circuit. This sets the stage for further investigating the usage of tDCS in repetitive disorders such as TS.

Single-unit activity of the anterior Globus pallidus internus in Tourette patients and posterior Globus pallidus internus in dystonic patients

OBJECTIVES

Our goal was to provide a detailed analysis of neurons' electrophysiological activity recorded in sub-territories of Globus pallidus internus (GPi) used as Deep Brain Stimulation (DBS) targets for these clinical conditions to potentially assist electrode targeting.

METHODS

We used intra-operative microelectrode recording during stereotactic neurosurgery to guide implantation of DBS lead.

RESULTS

Units in the medial anterior part of GPi of 7 Tourette's syndrome patients under general anesthesia were firing at mean and median rate of 32.1 and 21 Hz respectively (n = 101), with 45% of spikes fired during bursts and 21.3 bursts per minute. In the latero-posterior part of GPi of 7 dystonic patients under local anesthesia the mean and median activity were 46.1 and 30.6 Hz respectively (n = 27), and a mean of 21.7 bursts per minute was observed, with 30% of all spikes occurring during these bursts.

CONCLUSION

Units activity pattern - slow-regular, fast-irregular or fast-regular were present in different proportions between the two targets.

SIGNIFICANCE

The electrophysiological characteristics of the medial-anterior part of GPi and its latero-posterior portion can be used to assist DBS electrode targeting and also support the refinement of pathophysiological models of Tourette's syndrome and Dystonia.

Organic bioelectronics in medicine

A major challenge in the growing field of bioelectronic medicine is the development of tissue interface technologies promoting device integration with biological tissues. Materials based on organic bioelectronics show great promise due to a unique combination of electronic and ionic conductivity properties. In this review, we outline exciting developments in the field of organic bioelectronics and demonstrate the medical importance of these active, electronically controllable materials. Importantly, organic bioelectronics offer a means to control cell-surface attachment as required for many device-tissue applications. Experiments have shown that cells readily attach and proliferate on reduced but not oxidized organic bioelectronic materials. In another application, the active properties of organic bioelectronics were used to develop electronically triggered systems for drug release. After incorporating drugs by advanced loading strategies, small compound drugs were released upon electrochemical trigger, independent of charge. Another type of delivery device was used to achieve well-controlled, spatiotemporal delivery of cationic drugs. Via electrophoretic transport within a polymer, cations were delivered with single-cell precision. Finally, organic bioelectronic materials are commonly used as electrode coatings improving the electrical properties of recording and stimulation electrodes. Because such coatings drastically reduce the electrode impedance, smaller electrodes with improved signal-to-noise ratio can be fabricated. Thus, rapid technological advancement combined with the creation of tiny electronic devices reacting to changes in the tissue environment helps to promote the transition from standard pharmaceutical therapy to treatment based on 'electroceuticals'. Moreover, the widening repertoire of organic bioelectronics will expand the options for true biological interfaces, providing the basis for personalized bioelectronic medicine.

The Use of Deep Brain Stimulation in Tourette Syndrome

Tourette syndrome (TS) is a childhood neurobehavioural disorder, characterised by the presence of motor and vocal tics, typically starting in childhood but persisting in around 20% of patients into adulthood. In those patients who do not respond to pharmacological or behavioural therapy, deep brain stimulation (DBS) may be a suitable option for potential symptom improvement. This manuscript attempts to summarise the outcomes of DBS at different targets, explore the possible mechanisms of action of DBS in TS, as well as the potential of adaptive DBS. There will also be a focus on the future challenges faced in designing optimized trials.

Recent Advances in Understanding and Managing Tourette Syndrome

Tourette syndrome (TS) is a neurologic and behavioral disorder consisting of motor and phonic tics with onset in childhood or adolescence. The severity of tics can range from barely perceptible to severely impairing due to social embarrassment, discomfort, self-injury, and interference with daily functioning and school or work performance. In addition to tics, most patients with TS have a variety of behavioral comorbidities, including attention deficit hyperactivity disorder and obsessive-compulsive disorder. Studies evaluating the pathophysiology of tics have pointed towards dysfunction of the cortico-striato-thalamo-cortical circuit, but the mechanism of this hyperkinetic movement disorder is not well understood. Treatment of TS is multidisciplinary, typically involving behavioral therapy, oral medications, and botulinum toxin injections. Deep brain stimulation may be considered for “malignant” TS that is refractory to conventional therapy. In this review, we will highlight recent developments in the understanding and management strategies of TS.