The use of deep brain stimulation in Tourette's syndrome

Structural, Functional, and Genetic Changes Surrounding Electrodes Implanted in the Brain

Implantable neurotechnology enables monitoring and stimulating of the brain signals responsible for performing cognitive, motor, and sensory tasks. Electrode arrays implanted in the brain are increasingly used in the clinic to treat a variety of sources of neurological diseases and injuries. However, the implantation of a foreign body typically initiates a tissue response characterized by physical disruption of vasculature and the neuropil as well as the initiation of inflammation and the induction of reactive glial states. Likewise, electrical stimulation can induce damage to the surrounding tissue depending on the intensity and waveform parameters of the applied stimulus. These phenomena, in turn, are likely influenced by the surface chemistry and characteristics of the materials employed, but further information is needed to effectively link the biological responses observed to specific aspects of device design. In order to inform improved design of implantable neurotechnology, we are investigating the basic science principles governing device-tissue integration. We are employing multiple techniques to characterize the structural, functional, and genetic changes that occur in the cells surrounding implanted electrodes. First, we have developed a new "device-in-slice" technique to capture chronically implanted electrodes within thick slices of live rat brain tissue for interrogation with single-cell electrophysiology and two-photon imaging techniques. Our data revealed several new observations of tissue remodeling surrounding devices: (a) there was significant disruption of dendritic arbors in neurons near implants, where losses were driven asymmetrically on the implant-facing side. (b) There was a significant loss of dendritic spine densities in neurons near implants, with a shift toward more immature (nonfunctional) morphologies. (c) There was a reduction in excitatory neurotransmission surrounding implants, as evidenced by a reduction in the frequency of excitatory postsynaptic currents (EPSCs). Lastly, (d) there were changes in the electrophysiological underpinnings of neuronal spiking regularity. In parallel, we initiated new studies to explore changes in gene expression surrounding devices through spatial transcriptomics, which we applied to both recording and stimulating arrays. We found that (a) device implantation is associated with the induction of hundreds of genes associated with neuroinflammation, glial reactivity, oligodendrocyte function, and cellular metabolism and (b) electrical stimulation induces gene expression associated with damage or plasticity in a manner dependent upon the intensity of the applied stimulus. We are currently developing computational analysis tools to distill biomarkers of device-tissue interactions from large transcriptomics data sets. These results improve the current understanding of the biological response to electrodes implanted in the brain while producing new biomarkers for benchmarking the effects of novel electrode designs on responses. As the next generation of neurotechnology is developed, it will be increasingly important to understand the influence of novel materials, surface chemistries, and implant architectures on device performance as well as the relationship with the induction of specific cellular signaling pathways.

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.

Effects of Chemogenetic Inhibition of D1 or D2 Receptor-Containing Neurons of the Substantia Nigra and Striatum in Mice With Tourette Syndrome

As tourette syndrome (TS) is a common neurobehavioral disorder, the primary symptoms of which include behavioral stereotypies. Dysfunction of the substantia nigra-striatum network could be the main pathogenesis of TS, which is closely associated with dopamine (DA) and its receptors. TS is often resistant to conventional treatments. Therefore, it is necessary to investigate the neurobiological mechanisms underlying its pathogenesis. In this study, we investigated whether chemogenetic activation or inhibition of dopaminergic D1 receptor (D1R)- or D2 receptor (D2R)-containing neurons in the substantia nigra pars compacta (SNpc) or dorsal striatum (dSTR) affected the stereotyped behavior and motor functions of TS mice. Intraperitoneal injection of 3,3'-iminodipropionitrile (IDPN) was used to induce TS in mice. Stereotyped behavior test and open-field, rotarod, and grip strength tests were performed to evaluate stereotyped behavior and motor functions, respectively. Immunofluorescence labeling was used to detect the co-labeling of virus fluorescence and D1R or D2R. We found that chemogenetic inhibition of D1R- or D2R-containing neurons in the SNpc and dSTR alleviated behavioral stereotypies and motor functions in TS mice. Chemogenetic activation of D1R-containing neurons in the dSTR aggravated behavioral stereotypies and motor functions in vehicle-treated mice, but neither was aggravated in TS mice. In conclusion, chemogenetic inhibition of D1R- or D2R-containing neurons in the SNpc and dSTR alleviated behavioral stereotypies of TS, providing a new treatment target for TS. Moreover, the activation of D1R-containing neurons in the dSTR may contribute to the pathogenesis of TS, which can be chosen as a more precise target for treatment.

Toward guiding principles for the design of biologically-integrated electrodes for the central nervous system

Innovation in electrode design has produced a myriad of new and creative strategies for interfacing the nervous system with softer, less invasive, more broadly distributed sites with high spatial resolution. However, despite rapid growth in the use of implanted electrode arrays in research and clinical applications, there are no broadly accepted guiding principles for the design of biocompatible chronic recording interfaces in the central nervous system (CNS). Studies suggest that the architecture and flexibility of devices play important roles in determining effective tissue integration: device feature dimensions (varying from 'sub'- to 'supra'-cellular scales, <10 µm to  >100 µm), Young's modulus, and bending modulus have all been identified as key features of design. However, critical knowledge gaps remain in the field with respect to the underlying motivation for these designs: (1) a systematic study of the relationship between device design features (materials, architecture, flexibility), biointegration, and signal quality needs to be performed, including controls for interaction effects between design features, (2) benchmarks for success need to be determined (biological integration, recording performance, longevity, stability), and (3) user results, particularly those that champion a specific design or electrode modification, need to be replicated across laboratories. Finally, the ancillary effects of factors such as tethering, site impedance and insertion method need to be considered. Here, we briefly review observations to-date of device design effects on tissue integration and performance, and then highlight the need for comprehensive and systematic testing of these effects moving forward.

Deep brain stimulation in pediatric dystonia: a systematic review

While deep brain stimulation (DBS) treatment is relatively rare in children, it may have a role in dystonia to reduce motor symptoms and disability. Pediatric DBS studies are sparse and limited by small sample size, and thus, outcomes are poorly understood. Thus, we performed a systematic review of the literature including studies of DBS for pediatric (age < 21) dystonia. Patient demographics, disease causes and characteristics, motor scores, and disability scores were recorded at baseline and at last post-operative follow-up. We identified 19 studies reporting DBS outcomes in 76 children with dystonia. Age at surgery was 13.8 ± 3.9 (mean ± SD) years, and 58% of individuals were male. Post-operative follow-up duration was 2.8 ± 2.8 years. Sixty-eight percent of patients had primary dystonia (PD), of whom 56% had a pathological mutation in DYT1 (DYT1+). Across all patients, regardless of dystonia type, 43.8 ± 36% improvement was seen in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor (-M) scores after DBS, while 43.7 ± 31% improvement was observed in BFMDRS disability (-D) scores. Patients with PD were more likely to experience ≥ 50% improvement (56%) in BFMDRS-M scores compared to patients with secondary causes of dystonia (21%, p = 0.004). DYT1+ patients were more likely to achieve ≥ 50% improvement (65%) in BFMDRS-D than DTY1- individuals (29%, p = 0.02), although there was no difference in BFMDRS-M ≥ 50% improvement rates between DYT1+ (66%) or DYT1- (43%) children (p = 0.11). While DBS is less common in pediatric patients, individuals with severe dystonia may receive worthwhile benefit with neuromodulation treatment.

Deep Brain Stimulation of the Globus Pallidus Internus in Patients with Intractable Tourette Syndrome: A 1-year Follow-up Study

Background:

Deep brain stimulation (DBS) has been a promising treatment for patients with refractory Tourette syndrome (TS) for more than a decade. Despite successful DBS treatment of TS in more than 100 patients worldwide, studies with a large patient sample and long-term follow-up assessments are still scarce. Accordingly, we investigated the clinical efficacy and safety of globus pallidus internus (GPi) DBS in the treatment of intractable TS in 24 patients with a 1-year follow-up assessment.

Methods:

Bilateral/unilateral GPi-DBS was performed in 24 patients with TS. We evaluated symptoms of tics and obsessive-compulsive disorder (OCD) through the Yale Global Tic Severity Scale (YGTSS) and Yale-Brown Obsessive-compulsive Scale (Y-BOCS). We used the Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC) to evaluate the safety of the treatment. We conducted follow-up assessments of all patients for at least 12 months (12–99 months).

Results:

Symptoms of tics and OCD were significantly relieved at a 12-month follow-up assessment. The mean YGTSS score was 74.04 ± 11.52, 49.83 ± 10.91, 32.58 ± 7.97, and 31.21 ± 8.87 at baseline, 3, 6, and 12 months, respectively. The mean YGTSS scores obtained at the follow-up assessments were significantly different from the baseline (P < 0.05). The improvement in motor tics was superior to that in phonic tics. The mean Y-BOCS scores were 21.61 ± 4.97, 18 ± 4.58, 14.39 ± 3.99, and 13.78 ± 4.56 at baseline, 3, 6, and 12 months, respectively (P < 0.05). We observed a remarkable improvement in psychiatric comorbidities, such as OCD and attention-deficit hyperactivity disorder, after the procedure. WAIS-RC scores were comparable before and after the operation. There were no severe postoperative complications.

Conclusion:

GPi-DBS appears to comprehensively alleviate tic symptoms and psychiatric comorbidities in patients with TS, thus significantly improving patients’ quality of life.

The thalamus as a relay station and gatekeeper: relevance to brain disorders

Here, we provide a review of behavioural, cognitive, and neural studies of the thalamus, including its role in attention, consciousness, sleep, and motor processes. We further discuss neuropsychological and brain disorders associated with thalamus function, including Parkinson’s disease, Alzheimer’s disease, Korsakoff’s syndrome, and sleep disorders. Importantly, we highlight how thalamus-related processes and disorders can be explained by the role of the thalamus as a relay station.

The Relationship between Neurocircuitry Dysfunctions and Attention Deficit Hyperactivity Disorder: A Review

The prefrontal cortex is the superlative structure of brain that needs the longest developmental and maturational duration that highlights the region of attention deficit hyperactivity disorder (ADHD) in neuroimaging studies. Prefrontal cortex functions generate enormously complex and its abundant feedback neurocircuitries with subcortical structures such as striatum and thalamus established through dual neural fibers. These microneurocircuitries are called corticostriatothalamocortical (CSTC) circuits. The CSTC circuits paly an essential role in flexible behaviors. The impaired circuits increase the risk of behavioral and psychological symptoms. ADHD is an especial developmental stage of paediatric disease. It has been reported that the CSTC circuits dysfunctions in ADHD are related to homologous symptoms. This study aimed to review the symptoms of ADHD and discuss the recent advances on the effects of the disease as well as the new progress of treatments with each circuit.

The International Deep Brain Stimulation Registry and Database for Gilles de la Tourette Syndrome: How Does It Work?

Tourette Syndrome (TS) is a neuropsychiatric disease characterized by a combination of motor and vocal tics. Deep brain stimulation (DBS), already widely utilized for Parkinson's disease and other movement disorders, is an emerging therapy for select and severe cases of TS that are resistant to medication and behavioral therapy. Over the last two decades, DBS has been used experimentally to manage severe TS cases. The results of case reports and small case series have been variable but in general positive. The reported interventions have, however, been variable, and there remain non-standardized selection criteria, various brain targets, differences in hardware, as well as variability in the programming parameters utilized. DBS centers perform only a handful of TS DBS cases each year, making large-scale outcomes difficult to study and to interpret. These limitations, coupled with the variable effect of surgery, and the overall small numbers of TS patients with DBS worldwide, have delayed regulatory agency approval (e.g., FDA and equivalent agencies around the world). The Tourette Association of America, in response to the worldwide need for a more organized and collaborative effort, launched an international TS DBS registry and database. The main goal of the project has been to share data, uncover best practices, improve outcomes, and to provide critical information to regulatory agencies. The international registry and database has improved the communication and collaboration among TS DBS centers worldwide. In this paper we will review some of the key operation details for the international TS DBS database and registry.

The International Deep Brain Stimulation Registry and Database for Gilles de la Tourette Syndrome: How Does It Work?

Tourette Syndrome (TS) is a neuropsychiatric disease characterized by a combination of motor and vocal tics. Deep brain stimulation (DBS), already widely utilized for Parkinson's disease and other movement disorders, is an emerging therapy for select and severe cases of TS that are resistant to medication and behavioral therapy. Over the last two decades, DBS has been used experimentally to manage severe TS cases. The results of case reports and small case series have been variable but in general positive. The reported interventions have, however, been variable, and there remain non-standardized selection criteria, various brain targets, differences in hardware, as well as variability in the programming parameters utilized. DBS centers perform only a handful of TS DBS cases each year, making large-scale outcomes difficult to study and to interpret. These limitations, coupled with the variable effect of surgery, and the overall small numbers of TS patients with DBS worldwide, have delayed regulatory agency approval (e.g., FDA and equivalent agencies around the world). The Tourette Association of America, in response to the worldwide need for a more organized and collaborative effort, launched an international TS DBS registry and database. The main goal of the project has been to share data, uncover best practices, improve outcomes, and to provide critical information to regulatory agencies. The international registry and database has improved the communication and collaboration among TS DBS centers worldwide. In this paper we will review some of the key operation details for the international TS DBS database and registry.

A novel combinational approach of microstimulation and bioluminescence imaging to study the mechanisms of action of cerebral electrical stimulation in mice

Deep brain stimulation (DBS) is used to treat a number of neurological conditions and is currently being tested to intervene in neuropsychiatric conditions. However, a better understanding of how it works would ensure that side effects could be minimized and benefits optimized. We have thus developed a unique device to perform brain stimulation (BS) in mice and to address fundamental issues related to this methodology in the pre-clinical setting. This new microstimulator prototype was specifically designed to allow simultaneous live bioluminescence imaging of the mouse brain, allowing real time assessment of the impact of stimulation on cerebral tissue. We validated the authenticity of this tool in vivo by analysing the expression of toll-like receptor 2 (TLR2), corresponding to the microglial response, in the stimulated brain regions of TLR2-fluc-GFP transgenic mice, which we further corroborated with post-mortem analyses in these animals as well as in human brains of patients who underwent DBS to treat their Parkinson's disease. In the present study, we report on the development of the first BS device that allows for simultaneous live in vivo imaging in mice. This tool opens up a whole new range of possibilities that allow a better understanding of BS and how to optimize its effects through its use in murine models of disease.