Motor Improvement and Emotional Stabilization in Patients With Tourette Syndrome After Deep Brain Stimulation of the Ventral Anterior and Ventrolateral Motor Part of the Thalamus

Co-Occurring Anxiety in Youth with Tic Disorders: A Review

Objective: To review the current state of the literature regarding anxiety symptoms and anxiety disorders in chronic tic disorder (CTD). Results: We conducted a literature search on anxiety and tic disorders. Anxiety symptoms and anxiety disorders are common in youth with CTD, with ∼30%-50% of youth with CTD having at least one co-occurring anxiety disorder. Tics often improve by young adulthood but anxiety symptoms tend to persist, or worsen, over time. Anxiety and tics are closely related, but the exact nature of their relationship is poorly understood. We discuss some potential ways in which anxiety and tics are linked with an emphasis on the underlying brain circuitry involved. The relationship between anxiety and tics may be related to the premonitory urge. In addition, stress hormones may link anxiety and tics. Individuals with CTD have greater activation of their hypothalamic-pituitary-adrenal system in response to acute stress. We also review the impact of anxiety on youth with CTD and approaches to management of anxiety in youth. Conclusions: Anxiety is common in youth with CTD, is associated with more severe CTD, and can adversely affect a child's function. Thus, it is important to identify anxiety disorders in CTD and manage them appropriately.

Structural changes in the thalamus and its subregions in regulating different symptoms of posttraumatic stress disorder

As a key center for sensory information processing and transmission, the thalamus plays a crucial role in the development of posttraumatic stress disorder (PTSD). However, the changes in the thalamus and its role in regulating different PTSD symptoms remain unclear. In this study, fourteen PTSD patients and eighteen healthy controls (HCs) were recruited. All subjects underwent whole-brain T1-weighted three-dimensional Magnetization Prepared Rapid Gradient Echo Imaging scans. Gray matter volume (GMV) in the thalamus and its subregions were estimated using voxel-based morphometry (VBM). Compared to HCs, PTSD patients exhibited significant GMV reduction in the left thalamus and its subregions, including anterior, mediodorsal, ventral-lateral-dorsal (VLD), ventral-anterior, and ventral-lateral-ventral (VLV). Among the significantly reduced thalamic subregions, we found positive correlations between the GMV values of the left VLD and VLV and the re-experiencing symptoms score, arousal symptoms score, and total CAPS score. When using the symptom-related GMV values of left VLV and VLD in combination as a predictor, receiver operating characteristic (ROC) analysis revealed that the area under the curve (AUC) for binary classification reached 0.813. This study highlights the neurobiological mechanisms of PTSD related to thalamic changes and may provide potential imaging markers for diagnosis and therapy targets.

Mapping a network for tics in Tourette syndrome using causal lesions and structural alterations

Tics are sudden stereotyped movements or vocalizations. Cases of lesion-induced tics are invaluable, allowing for causal links between symptoms and brain structures. While a lesion network for tics has recently been identified, the degree to which this network translates to Tourette syndrome has not been fully elucidated. This is important given that patients with Tourette syndrome make up a large portion of tic cases; therefore, existing and future treatments should apply to these patients. The aim of this study was to first localize a causal network for tics from lesion-induced cases and then refine and validate this network in patients with Tourette syndrome. We independently performed 'lesion network mapping' using a large normative functional connectome (n = 1000) to isolate a brain network commonly connected to lesions causing tics (n = 19) identified through a systematic search. The specificity of this network to tics was assessed through comparison to lesions causing other movement disorders. Using structural brain coordinates from prior neuroimaging studies (n = 7), we then derived a neural network for Tourette syndrome. This was done using standard anatomical likelihood estimation meta-analysis and a novel method termed 'coordinate network mapping', which uses the same coordinates, yet maps their connectivity using the aforementioned functional connectome. Conjunction analysis was used to refine the network for lesion-induced tics to Tourette syndrome by identifying regions common to both lesion and structural networks. We then tested whether connectivity from this common network is abnormal in a separate resting-state functional connectivity MRI data set from idiopathic Tourette syndrome patients (n = 21) and healthy controls (n = 25). Results showed that lesions causing tics were distributed throughout the brain; however, consistent with a recent study, these were part of a common network with predominant basal ganglia connectivity. Using conjunction analysis, coordinate network mapping findings refined the lesion network to the posterior putamen, caudate nucleus, globus pallidus externus (positive connectivity) and precuneus (negative connectivity). Functional connectivity from this positive network to frontal and cingulate regions was abnormal in patients with idiopathic Tourette syndrome. These findings identify a network derived from lesion-induced and idiopathic data, providing insight into the pathophysiology of tics in Tourette syndrome. Connectivity to our cortical cluster in the precuneus offers an exciting opportunity for non-invasive brain stimulation protocols.

Reexperiencing and anxious arousal symptoms in relation to volumes of thalamus nuclei in posttraumatic stress spectrum adults

INTRODUCTION

Trauma reexperiencing is dominated by recollection of sensory-perceptual elements of the trauma, pointing to involvement of the sensory thalamus. This study examined posttraumatic stress symptoms in relation to volumes of thalamic nuclei that were grouped based on their predominant functions. We hypothesized that reexperiencing, controlling for other symptom dimensions, would correlate with volumes of thalamic nuclei involved in primary and higher-order sensory processing.

METHODS

Seventy-two trauma-exposed adults were interviewed with the Clinician Administered PTSD Scale for DSM-IV and underwent 3T magnetic resonance imaging. Scores were derived for reexperiencing, anxious arousal, dysphoric arousal, emotional numbing, and avoidance symptoms. These were entered as simultaneous predictors in five separate regression analyses, with age, sex, and total thalamus volume as covariates, predicting volumesf of five thalamus nuclear groupings corrected for intracranial volume: Specific sensory, associative-sensory, associative-cognitive, intralaminar, and motor groupings.

RESULTS

Reexperiencing symptoms were significantly positively correlated with volumes of the motor thalamic grouping, which included the ventral anterior, ventral lateral, and ventromedial nuclei. Anxious arousal was significantly negatively correlated with volumes of all five thalamic groupings.

CONCLUSIONS

Reexperiencing symptoms were correlated with volumes of the motor thalamus, while anxious arousal symptoms were related to all thalamic subregion volumes. Thalamic nuclei involved in motor functions, including oculomotor control and motor planning, may be implicated in posttraumatic reexperiencing symptoms.

Long-term efficacy, prognostic factors, and safety of deep brain stimulation in patients with refractory Tourette syndrome: A single center, single target, retrospective study

BACKGROUND

To evaluate the long-term efficacy, prognostic factors, and safety of posteroventral globus pallidus internus deep brain stimulation (DBS) in patients with refractory Tourette syndrome (RTS).

METHODS

This retrospective study recruited 61 patients with RTS who underwent posteroventral globus pallidus internus (GPi) DBS from January 2010 to December 2020 at the Chinese People's Liberation Army General Hospital. The Yale Global Tic Severity Scale (YGTSS), Yale-Brown Obsessive-Compulsive Scale (YBOCS), Beck Depression Inventory (BDI), Gilles de la Tourette Syndrome Quality-of-Life Scale (GTS-QOL) were used to evaluate the preoperative and postoperative clinical condition in all patients. Prognostic factors and adverse events following surgery were analyzed.

RESULTS

Patient follow up was conducted for an average of 73.33 ± 28.44 months. The final postoperative YGTSS (32.39 ± 22.34 vs 76.61 ± 17.07), YBOCS (11.26 ± 5.57 vs 18.31 ± 8.55), BDI (14.36 ± 8.16 vs 24.79 ± 11.03) and GTS-QOL (39.69 ± 18.29 vs 78.08 ± 14.52) scores at the end of the follow-up period were significantly lower than those before the surgery (p < 0.05). While age and the duration of follow-up were closely related to prognosis, the disease duration and gender were not. No serious adverse events were observed and only one patient exhibited symptomatic deterioration.

CONCLUSIONS

Posteroventral-GPI DBS provides long-term effectiveness, acceptable safety and can improve the quality of life in RTS patients. Moreover, DBS is more successful among younger patients and with longer treatment duration.

Neurosurgical management of Tourette syndrome: A literature review and analysis of a case series treated with deep brain stimulation

Tourette syndrome (TS) is a heterogeneous disorder, which clinical presentation includes both multiple motor and vocal tics and commonly associated psychiatric conditions (obsessive-compulsive disorder, attention deficit hyperactivity disorder, depression, anxiety, etc.). Treatment options primarily consist of non-pharmacological interventions (habit reversal training, relaxation techniques, cognitive behavioral therapy, and social rehabilitation) and pharmacotherapy. In case of the intractable forms, neurosurgical treatment may be considered, primarily deep brain stimulation (DBS). DBS appear to be effective in medically intractable TS patients, although, the preferential brain target is still not defined. The majority of studies describe small number of cases and the issues of appropriate patient selection and ethics remain to be clarified. In this article, we review the main points in management of TS, discuss possible indications and contraindications for neurosurgical treatment, and analyze our experience of DBS in a case series of refractory TS patients with the focus on target selection and individual outcomes.

Tourette Syndrome Treatment Updates: a Review and Discussion of the Current and Upcoming Literature

Purpose of Review

This study aims to examine the treatments currently available for Tourette syndrome (TS) and to discuss evolving therapies, spanning behavioral, pharmacologic, complementary and alternative medicine, and neuromodulation approaches.

Recent Findings

Behavioral therapies have undergone several modifications to improve accessibility, including transitioning to a virtual format which is particularly important in the current pandemic. There are several recent or ongoing pharmacologic studies that have shown promise including the selective D1 receptor antagonist ecopipam and various cannabinoid compounds. Adaptive DBS may enable the physiologic markers of tics to determine stimulation parameters and improve tic outcomes related to neuromodulation.

Summary

In recent years, there has been a wealth of research across multiple treatment domains in the TS field. This review highlights exciting and new potential options for the future treatment of patients with TS.

European clinical guidelines for Tourette syndrome and other tic disorders-version 2.0. Part IV: deep brain stimulation

In 2011 the European Society for the Study of Tourette Syndrome (ESSTS) published its first European clinical guidelines for the treatment of Tourette Syndrome (TS) with part IV on deep brain stimulation (DBS). Here, we present a revised version of these guidelines with updated recommendations based on the current literature covering the last decade as well as a survey among ESSTS experts. Currently, data from the International Tourette DBS Registry and Database, two meta-analyses, and eight randomized controlled trials (RCTs) are available. Interpretation of outcomes is limited by small sample sizes and short follow-up periods. Compared to open uncontrolled case studies, RCTs report less favorable outcomes with conflicting results. This could be related to several different aspects including methodological issues, but also substantial placebo effects. These guidelines, therefore, not only present currently available data from open and controlled studies, but also include expert knowledge. Although the overall database has increased in size since 2011, definite conclusions regarding the efficacy and tolerability of DBS in TS are still open to debate. Therefore, we continue to consider DBS for TS as an experimental treatment that should be used only in carefully selected, severely affected and otherwise treatment-resistant patients.

Measurement of Lead Localization Accuracy Based on Magnetic Resonance Imaging

Post-implantation localization of deep brain stimulation (DBS) lead based on a magnetic resonance (MR) image is widely used. Existing localization methods use artifact center method or template registration method, which may lead to a considerable deviation of > 2 mm, and result in severe side effects or even surgical failure. Accurate measurement of lead position can instantly inform surgeons of the imprecise implantation. This study aimed to identify the influencing factors in DBS lead post-implantation localization approach, analyze their influence, and describe a localization approach that uses the individual template method to reduce the deviation. We verified that reconstructing direction should be parallel or perpendicular to lead direction, instead of the magnetic field. Besides, we used simplified relationship between magnetic field angle and deviation error to correct the localization results. The mean localization error can be reduced after correction and favors the feasibility of direct localization of DBS lead using MR images. We also discussed influence of in vivo noise on localization frequency and the possibility of using only MR images to localize the contacts.

Target-Specific Effects of Deep Brain Stimulation for Tourette Syndrome: A Systematic Review and Meta-Analysis

Background: Extended research has pointed to the efficacy of deep brain stimulation (DBS) in treatment of patients with treatment-refractory Tourette syndrome (TS). The four most commonly used DBS targets for TS include the centromedian nucleus-nucleus ventrooralis internus (CM-Voi) and the centromedian nucleus-parafascicular (CM-Pf) complexes of the thalamus, and the posteroventrolateral (pvIGPi) and the anteromedial portion of the globus pallidus internus (amGPi). Differences and commonalities between those targets need to be compared systematically. Objective: Therefore, we evaluated whether DBS is effective in reducing TS symptoms and target-specific differences. Methods: A PubMed literature search was conducted according to the PRISMA guidelines. Eligible literature was used to conduct a systematic review and meta-analysis. Results: In total, 65 studies with 376 patients were included. Overall, Yale Global Tic Severity Scale (YGTSS) scores were reduced by more than 50 in 69% of the patients. DBS also resulted in significant reductions of secondary outcome measures, including the total YGTSS, modified Rush Video-Based Tic Rating Scale (mRVRS), Yale-Brown Obsessive Compulsive Scale (YBOCS), and Becks Depression Inventory (BDI). All targets resulted in significant reductions of YGTSS scores and, with the exception of the CM-Pf, also in reduced YBOCS scores. Interestingly, DBS of pallidal targets showed increased YGTSS and YBOCS reductions compared to thalamic targets. Also, the meta-analysis including six randomized controlled and double-blinded trials demonstrated clinical efficacy of DBS for TS, that remained significant for GPi but not thalamic stimulation in two separate meta-analyses. Conclusion: We conclude that DBS is a clinically effective treatment option for patients with treatment-refractory TS, with all targets showing comparable improvement rates. Future research might focus on personalized and symptom-specific target selection.

Therapeutic Neurostimulation in Obsessive-Compulsive and Related Disorders: A Systematic Review

Invasive and noninvasive neurostimulation therapies for obsessive-compulsive and related disorders (OCRD) were systematically reviewed with the aim of assessing clinical characteristics, methodologies, neuroanatomical substrates, and varied stimulation parameters. Previous reviews have focused on a narrow scope, statistical rather than clinical significance, grouped together heterogenous protocols, and proposed inconclusive outcomes and directions. Herein, a comprehensive and transdiagnostic evaluation of all clinically relevant determinants is presented with translational clinical recommendations and novel response rates. Electroconvulsive therapy (ECT) studies were limited in number and quality but demonstrated greater efficacy than previously identified. Targeting the pre-SMA/SMA is recommended for transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS). TMS yielded superior outcomes, although polarity findings were conflicting, and refinement of frontal/cognitive control protocols may optimize outcomes. For both techniques, standardization of polarity, more treatment sessions (>20), and targeting multiple structures are encouraged. A deep brain stimulation (DBS) 'sweet spot' of the striatum for OCD was proposed, and CBT is strongly encouraged. Tourette's patients showed less variance and reliance on treatment optimization. Several DBS targets achieved consistent, rapid, and sustained clinical response. Analysis of fiber connectivity, as opposed to precise neural regions, should be implemented for target selection. Standardization of protocols is necessary to achieve translational outcomes.

Thalamic deep brain stimulation for Tourette Syndrome: A naturalistic trial with brief randomized, double-blinded sham-controlled periods

BACKGROUND

There is still a lack of controlled studies to prove efficacy of thalamic deep brain stimulation for Tourette's Syndrome.

OBJECTIVES

In this controlled trial, we investigated the course of tic severity, comorbidities and quality of life during thalamic stimulation and whether changes in tic severity can be assigned to ongoing compared to sham stimulation.

METHODS

We included eight adult patients with medically refractory Tourette's syndrome. Bilateral electrodes were implanted in the centromedian-parafascicular-complex and the nucleus ventro-oralis internus. Tic severity, quality of life and comorbidities were assessed before surgery as well as six and twelve months after. Short randomized, double-blinded sham-controlled crossover sequences with either active or sham stimulation were implemented at both six- and twelve-months' assessments. The primary outcome measurement was the difference in the Yale Global Tic Severity Scale tic score between active and sham stimulation. Adverse events were systematically surveyed for all patients to evaluate safety.

RESULTS

Active stimulation resulted in significantly higher tic reductions than sham stimulation (F = 79.5; p = 0.001). Overall quality of life and comorbidities improved significantly in the open-label-phase. Over the course of the trial two severe adverse events occurred that were resolved without sequelae.

CONCLUSION

Our results provide evidence that thalamic stimulation is effective in improving tic severity and overall quality of life. Crucially, the reduction of tic severity was primarily driven by active stimulation. Further research may focus on improving stimulation protocols and refining patient selection to improve efficacy and safety of deep brain stimulation for Tourette's Syndrome.

Deep brain stimulation in the management of paediatric neuropsychiatric conditions: Current evidence and future directions

INTRODUCTION

Neurosurgery has provided an alternative option for patients with refractory psychiatric indications. Lesion procedures were the initial techniques used, but deep brain stimulation (DBS) has the advantage of relative reversibility and adjustability. This review sets out to delineate the current evidence for DBS use in psychiatric conditions, with an emphasis on the paediatric population, highlighting pitfalls and opportunities.

METHODS

A systematic review of the literature was conducted on studies reporting the use of DBS in the management of psychiatric disorders. The PRISMA guidelines were employed to structure the review of the literature. Data was discussed focusing on the indications for DBS management of psychiatric conditions in the paediatric age group.

RESULTS

A total of seventy-three full-text papers reported the use of DBS surgery for the management of psychiatric conditions matching the inclusion criteria. The main indications were Tourette Syndrome (GTS) (15 studies), Obsessive Compulsive Disorder (OCD) (20), Treatment Resistant Depression (TRD) (27), Eating Disorders (ED) (7) and Aggressive Behaviour and self-harm (AB) (4). Out of these, only 11 studies included patients in the paediatric age group (≤18 years-old). Among the paediatric patients, the indications for surgery included GTS, AB and ED.

CONCLUSIONS

The application of deep brain stimulation for psychiatric indications has progressed at a steady pace in the adult population and at a much slower pace in the paediatric population. Future studies in children should be done in a trial setting with strict and robust criteria. A move towards personalising DBS therapy with new stimulation paradigms will provide new frontiers and possibilities in this growing field.

The 5 Pillars in Tourette Syndrome Deep Brain Stimulation Patient Selection: Present and Future

The selection of patients with Tourette syndrome (TS) for deep brain stimulation (DBS) surgery rests on 5 fundamental pillars. However, the operationalization of the multidisciplinary screening process to evaluate these pillars remains highly diverse, especially across sites. High tic severity and tic-related impact on quality of life (first 2 pillars) require confirmation from objective, validated measures, but malignant features of TS should per se suffice to fulfill this pillar. Failure of behavioral and pharmacologic therapies (third pillar) should be assessed taking into account refractoriness through objective and subjective measures supporting lack of efficacy of all interventions of proven efficacy, as well as true lack of tolerability, adherence, or access. Educational interventions and use of remote delivery formats (for behavioral therapies) play a role in preventing misjudgment of treatment failure. Stability of comorbid psychiatric disorders for 6 months (fourth pillar) is needed to confirm the predominant impact of tics on quality of life, to prevent pseudo-refractoriness, and to maximize the future DBS response. The 18-year age limit (fifth pillar) is currently under reappraisal, considering the potential impact of severe tics in adolescence and the predictive effect of tic severity in childhood on tic severity when transitioning into adulthood. Future advances should aim at a consensus-based definition of failure of specific, noninvasive treatment strategies for tics and of the minimum clinical observation period before considering DBS treatment, the stability of behavioral comorbidities, and the use of a prospective international registry data to identify predictors of positive response to DBS, especially in younger patients.

Electroacupuncture Alleviates Chronic Pain-Induced Anxiety Disorders by Regulating the rACC-Thalamus Circuitry

Anxiety is a common comorbidity associated with chronic pain, which results in chronic pain complexification and difficulty in treatment. Electroacupuncture (EA) is commonly used to treat chronic pain and anxiety. However, the underlying mechanisms of the EA effect are largely unknown. Here, we showed that a circuitry underlying chronic pain induces anxiety disorders, and EA can treat them by regulating such circuitry. Using chemogenetic methods, we found that chemogenetic activation of the rostral anterior cingulate cortex (rACC) glutamatergic output to the thalamus induced anxiety disorders in control rats. Then, chemogenetic inhibition of the rACC-thalamus circuitry reduced anxiety-like behavior produced by intraplantar injection of the complete Freund's adjuvant (CFA). In this study, we examined the effects of EA on a rat model of CFA-mediated anxiety-like behaviors and the related mechanisms. We found that chemogenetic activation of the rACC-thalamus circuitry effectively blocked the effects of EA on chronic pain-induced anxiety-like behaviors in CFA rats. These results demonstrate an underlying rACC-thalamus glutamatergic circuitry that regulates CFA-mediated anxiety-like behaviors. This study also provides a potential mechanistic explanation for EA treatment of anxiety caused by chronic pain.

Connectivity Patterns of Deep Brain Stimulation Targets in Patients with Gilles de la Tourette Syndrome

Since 1999, several targets for deep brain stimulation (DBS) in Gilles de la Tourette syndrome (GTS) have emerged showing similar success rates. Studies using different tractography techniques have identified connectivity profiles associated with a better outcome for individual targets. However, GTS patients might need individualized therapy. The objective of this study is to analyze the connectivity profile of different DBS targets for GTS. We identified standard target coordinates for the centromedian nucleus/nucleus ventro-oralis internus (CM/Voi), the CM/parafascicular (CM-Pf) complex, the anteromedial globus pallidus internus (amGPi), the posteroventral GPi (pvGPi), the ventral anterior/ventrolateral thalamus (VA/VL), and the nucleus accumbens/anterior limb of the internal capsule (Nacc/ALIC). Probabilistic tractography was performed from the targets to different limbic and motor areas based on patient-specific imaging and a normative connectome (HCP). Our analysis showed significant differences between the connectivity profiles of standard DBS targets (p < 0.05). Among all targets, the pvGPi showed the strongest connection to the sensorimotor cortex, while the amGPi showed the strongest connection to the prefrontal cortex in patient-specific imaging. Differences were observed between the connectivity profiles when using probabilistic tractography based on patient data and HCP. Our findings showed that the connectivity profiles of different DBS targets to major motor and limbic areas differ significantly. In the future, these differences may be considered when planning DBS for GTS patients employing an individualized approach. There were compelling differences in connectivity profiles when using different tractography techniques.

Structural connectivity predicts clinical outcomes of deep brain stimulation for Tourette syndrome

Deep brain stimulation may be an effective therapy for select cases of severe, treatment-refractory Tourette syndrome; however, patient responses are variable, and there are no reliable methods to predict clinical outcomes. The objectives of this retrospective study were to identify the stimulation-dependent structural networks associated with improvements in tics and comorbid obsessive-compulsive behaviour, compare the networks across surgical targets, and determine if connectivity could be used to predict clinical outcomes. Volumes of tissue activated for a large multisite cohort of patients (n = 66) implanted bilaterally in globus pallidus internus (n = 34) or centromedial thalamus (n = 32) were used to generate probabilistic tractography to form a normative structural connectome. The tractography maps were used to identify networks that were correlated with improvement in tics or comorbid obsessive-compulsive behaviour and to predict clinical outcomes across the cohort. The correlated networks were then used to generate 'reverse' tractography to parcellate the total volume of stimulation across all patients to identify local regions to target or avoid. The results showed that for globus pallidus internus, connectivity to limbic networks, associative networks, caudate, thalamus, and cerebellum was positively correlated with improvement in tics; the model predicted clinical improvement scores (P = 0.003) and was robust to cross-validation. Regions near the anteromedial pallidum exhibited higher connectivity to the positively correlated networks than posteroventral pallidum, and volume of tissue activated overlap with this map was significantly correlated with tic improvement (P < 0.017). For centromedial thalamus, connectivity to sensorimotor networks, parietal-temporal-occipital networks, putamen, and cerebellum was positively correlated with tic improvement; the model predicted clinical improvement scores (P = 0.012) and was robust to cross-validation. Regions in the anterior/lateral centromedial thalamus exhibited higher connectivity to the positively correlated networks, but volume of tissue activated overlap with this map did not predict improvement (P > 0.23). For obsessive-compulsive behaviour, both targets showed that connectivity to the prefrontal cortex, orbitofrontal cortex, and cingulate cortex was positively correlated with improvement; however, only the centromedial thalamus maps predicted clinical outcomes across the cohort (P = 0.034), but the model was not robust to cross-validation. Collectively, the results demonstrate that the structural connectivity of the site of stimulation are likely important for mediating symptom improvement, and the networks involved in tic improvement may differ across surgical targets. These networks provide important insight on potential mechanisms and could be used to guide lead placement and stimulation parameter selection, as well as refine targets for neuromodulation therapies for Tourette syndrome.

Basal Ganglia Pathways Associated With Therapeutic Pallidal Deep Brain Stimulation for Tourette Syndrome

BACKGROUND

Deep brain stimulation (DBS) targeting the globus pallidus internus (GPi) can improve tics and comorbid obsessive-compulsive behavior (OCB) in patients with treatment-refractory Tourette syndrome (TS). However, some patients' symptoms remain unresponsive, the stimulation applied across patients is variable, and the mechanisms underlying improvement are unclear. Identifying the fiber pathways surrounding the GPi that are associated with improvement could provide mechanistic insight and refine targeting strategies to improve outcomes.

METHODS

Retrospective data were collected for 35 patients who underwent bilateral GPi DBS for TS. Computational models of fiber tract activation were constructed using patient-specific lead locations and stimulation settings to evaluate the effects of DBS on basal ganglia pathways and the internal capsule. We first evaluated the relationship between activation of individual pathways and symptom improvement. Next, linear mixed-effects models with combinations of pathways and clinical variables were compared in order to identify the best-fit predictive models of tic and OCB improvement.

RESULTS

The best-fit model of tic improvement included baseline severity and the associative pallido-subthalamic pathway. The best-fit model of OCB improvement included baseline severity and the sensorimotor pallido-subthalamic pathway, with substantial evidence also supporting the involvement of the prefrontal, motor, and premotor internal capsule pathways. The best-fit models of tic and OCB improvement predicted outcomes across the cohort and in cross-validation.

CONCLUSIONS

Differences in fiber pathway activation likely contribute to variable outcomes of DBS for TS. Computational models of pathway activation could be used to develop novel approaches for preoperative targeting and selecting stimulation parameters to improve patient outcomes.

Deep brain stimulation and sensorimotor gating in tourette syndrome and obsessive-compulsive disorder

Recent translational data suggest that deep brain stimulation (DBS) of the cortico-striato-thalamo-cortical (CSTC) loops improves sensorimotor gating in psychiatric disorders that show deficient prepulse inhibition (PPI), a robust operational measure of sensorimotor gating. To our knowledge we are the first to investigate this effect in patients with Tourette syndrome (TS). We measured PPI of the acoustic startle reflex in patients with TS (N = 10) or Obsessive-Compulsive Disorder (OCD) (N = 8) treated with DBS of the centromedian and ventro-oral internal thalamic nucleus and the anterior limb of internal capsule-nucleus accumbens area respectively, and aged- and gender-matched healthy controls (HC). PPI of the DBS groups was measured in randomized order in the ON and OFF stimulation condition. Statistical analysis revealed no significant difference in PPI (%) of patients with TS between ON (M = 20.5, SD = 14.9) and OFF (M = 25.2, SD = 29.7) condition. There were significantly reduced PPI levels in patients with TS in the ON condition compared to HC (M = 49.2, SD = 10.7), but no significant difference in PPI between TS in the OFF condition and HC. Furthermore, we found no significant stimulation or group effect for OCD and HC (OCD ON: M = 57.0, SD = 8.3; OCD OFF: 67.8, SD = 19.6; HC: M = 63.0, SD = 24.3). Our study has a number of limitations. Sample sizes are small due to the restricted patient collective. The study was not controlled for use of psychoactive medication or nicotine. Furthermore, we were not able to assess presurgical PPI measurements. In conclusion, we were able to show that PPI is impaired in patients with TS. This finding is in line with recent translational work. With respect to the OCD cohort we were not able to replicate our previously published data. A disability in sensorimotor gating plays a pivotal role in many psychiatric disorders therefore more research should be conducted to disentangle the potential and limitations of modulating sensorimotor gating via brain stimulation techniques.

Deep Brain Stimulation Results in Greater Symptomatic Improvement in Tourette Syndrome than Conservative Measures: A Meta-Analysis

INTRODUCTION

Deep brain stimulation (DBS) has emerged as a safe and effective therapy for refractory Tourette syndrome (TS). Recent studies have identified several neural targets as effective in reducing TS symptoms with DBS, but, to our knowledge, none has compared the effectiveness of DBS with conservative therapy.

METHODS

A literature review was performed to identify studies investigating adult patient outcomes reported as Yale Global Tic Severity Scale (YGTSS) scores after DBS surgery, pharmacotherapy, and psychotherapy. Data were pooled using a random-effects model of inverse variance-weighted meta-analysis (n = 168 for DBS, n = 131 for medications, and n = 154 for behavioral therapy).

RESULTS

DBS resulted in a significantly greater reduction in YGTSS total score (49.9 ± 17.5%) than pharmacotherapy (22.5 ± 15.2%, p = 0.001) or psychotherapy (20.0 ± 11.3%, p < 0.001), with a complication (adverse effect) rate of 0.15/case, 1.13/case, and 0.60/case, respectively.

CONCLUSION

Our data suggest that adult patients with refractory TS undergoing DBS experience greater symptomatic improvement with surprisingly low morbidity than can be obtained with pharmacotherapy or psychotherapy.

Deep Brain Stimulation for Tourette Syndrome: Potential Role in the Pediatric Population

Tourette syndrome (TS) is a complex neuropsychiatric disorder. Despite an expected natural history of improvement with age, many individuals continue to have severe tics and remain refractory to the current best pharmacologic and nonpharmacologic treatments. Deep brain stimulation (DBS) has emerged as a potential treatment option. This article reviews the published reports on the use of deep brain stimulation in Tourette syndrome revealing that 2 anatomical targets have been most commonly used: the centromedian thalamus and the globus pallidus internus. The evidence supports a significant clinical improvement of tics with deep brain stimulation, though the data are limited by the small number of patients and variable methodology employed. To bridge these limitations, the international Tourette syndrome deep brain stimulation database and registry have been created, fostering collaboration among multiple centers from 10 countries. By standardizing data collection, the database and registry are providing valuable insights into deep brain stimulation for Tourette syndrome. In conclusion, deep brain stimulation offers significant promise for the management of tics.

Deep brain stimulation for Tourette's syndrome

Tourette syndrome (TS) is a childhood-onset neuropsychiatric disorder characterized by the presence of multiple motor and vocal tics. TS usually co-occurs with one or multiple psychiatric disorders. Although behavioral and pharmacological treatments for TS are available, some patients do not respond to the available treatments. For these patients, TS is a severe, chronic, and disabling disorder. In recent years, deep brain stimulation (DBS) of basal ganglia-thalamocortical networks has emerged as a promising intervention for refractory TS with or without psychiatric comorbidities. Three major challenges need to be addressed to move the field of DBS treatment for TS forward: (1) patient and DBS target selection, (2) ethical concerns with treating pediatric patients, and (3) DBS treatment optimization and improvement of individual patient outcomes (motor and phonic tics, as well as functioning and quality of life). The Tourette Association of America and the American Academy of Neurology have recently released their recommendations regarding surgical treatment for refractory TS. Here, we describe the challenges, advancements, and promises of the use of DBS in the treatment of TS. We summarize the results of clinical studies and discuss the ethical issues involved in treating pediatric patients. Our aim is to provide a better understanding of the feasibility, safety, selection process, and clinical effectiveness of DBS treatment for select cases of severe and medically intractable TS.

Image-based analysis and long-term clinical outcomes of deep brain stimulation for Tourette syndrome: a multisite study

BACKGROUND

Deep brain stimulation (DBS) can be an effective therapy for tics and comorbidities in select cases of severe, treatment-refractory Tourette syndrome (TS). Clinical responses remain variable across patients, which may be attributed to differences in the location of the neuroanatomical regions being stimulated. We evaluated active contact locations and regions of stimulation across a large cohort of patients with TS in an effort to guide future targeting.

METHODS

We collected retrospective clinical data and imaging from 13 international sites on 123 patients. We assessed the effects of DBS over time in 110 patients who were implanted in the centromedial (CM) thalamus (n=51), globus pallidus internus (GPi) (n=47), nucleus accumbens/anterior limb of the internal capsule (n=4) or a combination of targets (n=8). Contact locations (n=70 patients) and volumes of tissue activated (n=63 patients) were coregistered to create probabilistic stimulation atlases.

RESULTS

Tics and obsessive-compulsive behaviour (OCB) significantly improved over time (p<0.01), and there were no significant differences across brain targets (p>0.05). The median time was 13 months to reach a 40% improvement in tics, and there were no significant differences across targets (p=0.84), presence of OCB (p=0.09) or age at implantation (p=0.08). Active contacts were generally clustered near the target nuclei, with some variability that may reflect differences in targeting protocols, lead models and contact configurations. There were regions within and surrounding GPi and CM thalamus that improved tics for some patients but were ineffective for others. Regions within, superior or medial to GPi were associated with a greater improvement in OCB than regions inferior to GPi.

CONCLUSION

The results collectively indicate that DBS may improve tics and OCB, the effects may develop over several months, and stimulation locations relative to structural anatomy alone may not predict response. This study was the first to visualise and evaluate the regions of stimulation across a large cohort of patients with TS to generate new hypotheses about potential targets for improving tics and comorbidities.

Cellular, molecular, and clinical mechanisms of action of deep brain stimulation-a systematic review on established indications and outlook on future developments

Deep brain stimulation (DBS) has been successfully used to treat movement disorders, such as Parkinson's disease, for more than 25 years and heralded the advent of electrical neuromodulation to treat diseases with dysregulated neuronal circuits. DBS is now superseding ablative techniques, such as stereotactic radiofrequency lesions. While serendipity has played a role in developing DBS as a therapy, research during the past two decades has shown that electrical neuromodulation is far more than a functional lesion that can be switched on and off. This understanding broadens the field to enable new types of stimulation, clinical indications, and research. This review highlights the complex effects of DBS from the single cell to the neuronal network. Specifically, we examine the electrical, cellular, molecular, and neurochemical mechanisms of DBS as applied to Parkinson's disease and other emerging applications.

Deep brain stimulation in Tourette's syndrome: evidence to date

Tourette's syndrome (TS) is a neurodevelopmental disorder that comprises vocal and motor tics associated with a high frequency of psychiatric comorbidities, which has an important impact on quality of life. The onset is mainly in childhood and the symptoms can either fade away or require pharmacological therapies associated with cognitive-behavior therapies. In rare cases, patients experience severe and disabling symptoms refractory to conventional treatments. In these cases, deep brain stimulation (DBS) can be considered as an interesting and effective option for symptomatic control. DBS has been studied in numerous trials as a therapy for movement disorders, and currently positive data supports that DBS is partially effective in reducing the motor and non-motor symptoms of TS. The average response, mostly from case series and prospective cohorts and only a few controlled studies, is around 40% improvement on tic severity scales. The ventromedial thalamus has been the preferred target, but more recently the globus pallidus internus has also gained some notoriety. The mechanism by which DBS is effective on tics and other symptoms in TS is not yet understood. As refractory TS is not common, even reference centers have difficulties in performing large controlled trials. However, studies that reproduce the current results in larger and multicenter randomized controlled trials to improve our knowledge so as to support the best target and stimulation settings are still lacking. This article will discuss the selection of the candidates, DBS targets and mechanisms on TS, and clinical evidence to date reviewing current literature about the use of DBS in the treatment of TS.

Deep brain stimulation of the supero-lateral branch of the medial forebrain bundle does not lead to changes in personality in patients suffering from severe depression

BACKGROUND

Reports of changes in patients' social behavior during deep brain stimulation (DBS) raised the question whether DBS induces changes in personality. This study explored if (1) DBS is associated with changes in personality in patients suffering from treatment-resistant depression (TRD), (2) how personality dimensions and depression are associated, and (3) if TRD patients' self-ratings of personality are valid.

METHODS

TRD patients were assessed before DBS (n = 30), 6 months (t2, n = 21), 2 (t3, n = 17) and 5 years (t4, n = 11) after the initiation of DBS of the supero-lateral branch of the medial forebrain bundle (slMFB-DBS). Personality was measured with the NEO-Five-Factor Inventory (NEO-FFI), depression severity with Hamilton (HDRS), and Montgomery-Åsberg Depression Rating Scale (MADRS).

RESULTS

Personality dimensions did not change with slMFB-DBS compared with baseline. Extraversion was negatively correlated with HDRS28 (r = -0.48, p < 0.05) and MADRS (r = -0.45, p < 0.05) at t2. Inter-rater reliability was high for the NEO-FFI at baseline (Cronbach's α = 0.74) and at t4 (α = 0.65). Extraversion [t(29) = -5.20; p < 0.001] and openness to experience [t(29) = -6.96; p < 0.001] differed statistically significant from the normative sample, and did not predict the antidepressant response.

CONCLUSIONS

slMFB-DBS was not associated with a change in personality. The severity of depression was associated with extraversion. Personality of TRD patients differed from the healthy population and did not change with response, indicating a possible scar effect. Self-ratings of personality seem valid to assess personality during TRD.

Deep brain stimulation for Gilles de la Tourette syndrome in children and youth: a meta-analysis with individual participant data

OBJECTIVE

Gilles de la Tourette syndrome (GTS) is a disorder characterized by motor and vocal tics. Although by definition the onset of GTS is before age 18 years, clinical trials of deep brain stimulation (DBS) have been conducted only in adults. Using individual participant data (IPD) meta-analysis methodology, the current study investigated the safety and efficacy of DBS as a treatment for GTS in children and youth.

METHODS

A systematic review with no date or language restrictions was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Three electronic databases were searched: PubMed, EMBASE, and Web of Science. From 843 articles screened, the IPD of 58 children and youth (ages 12–21 years) extracted from 21 articles were collected and analyzed. A mixed-effects univariable analysis followed by multivariable hierarchical regression was performed using change in the Yale Global Tic Severity Scale (YGTSS) score as the primary outcome and reported measures of comorbidities as secondary outcomes.

RESULTS

The authors’ results showed an average improvement of 57.5% ± 24.6% across studies on the YGTSS. They also found that comorbid depression and stimulation pulse width each correlated negatively with outcome (p < 0.05). In patients with less severe GTS, greater improvements were evident following thalamic stimulation. More than one-quarter (n = 16, 27.6%) of participants experienced side effects, the majority of which were minor.

CONCLUSIONS

DBS in the pediatric population may be an effective option with a moderate safety profile for treatment of GTS in carefully selected children and youth. Large, prospective studies with long-term follow-up are necessary to understand how DBS influences tic symptoms and may alter the natural course of GTS in children.

Global network modulation during thalamic stimulation for Tourette syndrome

Background and objectives

Deep brain stimulation (DBS) of the thalamus is a promising therapeutic alternative for treating medically refractory Tourette syndrome (TS). However, few human studies have examined its mechanism of action. Therefore, the networks that mediate the therapeutic effects of thalamic DBS remain poorly understood.

Methods

Five participants diagnosed with severe medically refractory TS underwent bilateral thalamic DBS stereotactic surgery. Intraoperative fMRI characterized the blood oxygen level-dependent (BOLD) response evoked by thalamic DBS and determined whether the therapeutic effectiveness of thalamic DBS, as assessed using the Modified Rush Video Rating Scale test, would correlate with evoked BOLD responses in motor and limbic cortical and subcortical regions.

Results

Our results reveal that thalamic stimulation in TS participants has wide-ranging effects that impact the frontostriatal, limbic, and motor networks. Thalamic stimulation induced suppression of motor and insula networks correlated with motor tic reduction, while suppression of frontal and parietal networks correlated with vocal tic reduction. These regions mapped closely to major regions of interest (ROI) identified in a nonhuman primate model of TS.

Conclusions

Overall, these findings suggest that a critical factor in TS treatment should involve modulation of both frontostriatal and motor networks, rather than be treated as a focal disorder of the brain. Using the novel combination of DBS-evoked tic reduction and fMRI in human subjects, we provide new insights into the basal ganglia-cerebellar-thalamo-cortical network-level mechanisms that influence the effects of thalamic DBS. Future translational research should identify whether these network changes are cause or effect of TS symptoms.

Deep Brain Stimulation-Possible Treatment Strategy for Pathologically Altered Body Weight?

The treatment of obesity and eating disorders such as binge-eating disorder or anorexia nervosa is challenging. Besides lifestyle changes and pharmacological options, bariatric surgery represents a well-established and effective-albeit invasive-treatment of obesity, whereas for binge-eating disorder and anorexia nervosa mostly psychotherapy options exist. Deep brain stimulation (DBS), a method that influences the neuronal network, is by now known for its safe and effective applicability in patients with Parkinson’s disease. However, the use does not seem to be restricted to these patients. Recent preclinical and first clinical evidence points towards the use of DBS in patients with obesity and eating disorders as well. Depending on the targeted area in the brain, DBS can either inhibit food intake and body weight or stimulate energy intake and subsequently body weight. The current review focuses on preclinical and clinical evidence of DBS to modulate food intake and body weight and highlight the different brain areas targeted, stimulation protocols applied and downstream signaling modulated. Lastly, this review will also critically discuss potential safety issues and gaps in knowledge to promote further studies.

An Emotional Call to Action: Integrating Affective Neuroscience in Models of Motor Control

Intimate relationships between emotion and action have long been acknowledged, yet contemporary theories and experimental research within affective and movement neuroscience have not been linked into a coherent framework bridging these two fields. Accumulating psychological and neuroimaging evidence has, however, brought new insights regarding how emotions affect the preparation, execution, and control of voluntary movement. Here we review main approaches and findings on such emotion–action interactions. To assimilate key emotion concepts of action tendencies and motive states with fundamental constructs of the motor system, we underscore the need for integrating an information-processing approach of motor control into affective neuroscience. This should provide a rich foundation to bridge the two fields, allowing further refinement and empirical testing of emotion theories and better understanding of affective influences in movement disorders.

Centrality of prefrontal and motor preparation cortices to Tourette Syndrome revealed by meta-analysis of task-based neuroimaging studies

Tourette Syndrome (TS) is a neurodevelopmental condition characterized by chronic multiple tics, which are experienced as compulsive and 'unwilled'. Patients with TS can differ markedly in the frequency, severity, and bodily distribution of tics. Moreover, there are high comorbidity rates with attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), anxiety disorders, and depression. This complex clinical profile may account for apparent variability of findings across neuroimaging studies that connect neural function to cognitive and motor behavior in TS. Here we crystalized information from neuroimaging regarding the functional circuitry of TS, and furthermore, tested specifically for neural determinants of tic severity, by applying activation likelihood estimation (ALE) meta-analyses to neuroimaging (activation) studies of TS. Fourteen task-based studies (13 fMRI and one H2O-PET) met rigorous inclusion criteria. These studies, encompassing 25 experiments and 651 participants, tested for differences between TS participants and healthy controls across cognitive, motor, perceptual and somatosensory domains. Relative to controls, TS participants showed distributed differences in the activation of prefrontal (inferior, middle, and superior frontal gyri), anterior cingulate, and motor preparation cortices (lateral premotor cortex and supplementary motor area; SMA). Differences also extended into sensory (somatosensory cortex and the lingual gyrus; V4); and temporo-parietal association cortices (posterior superior temporal sulcus, supramarginal gyrus, and retrosplenial cortex). Within TS participants, tic severity (reported using the Yale Global Tic Severity Scale; YGTSS) selectively correlated with engagement of SMA, precentral gyrus, and middle frontal gyrus across tasks. The dispersed involvement of multiple cortical regions with differences in functional reactivity may account for heterogeneity in the symptomatic expression of TS and its comorbidities. More specifically for tics and tic severity, the findings reinforce previously proposed contributions of premotor and lateral prefrontal cortices to tic expression.

Deep brain stimulation for psychiatric disorders: Is there an impact on social functioning?

BACKGROUND

Deep brain stimulation (DBS) for refractory psychiatric disorders shows promising effects on symptom-reduction, however, little is known regarding the effects of DBS on social outcome.

METHODS

A PubMed search based on original studies of DBS for psychiatric disorders [treatment resistant depression (TRD), Gilles de la Tourette's syndrome (GTS), and obsessive compulsive disorder (OCD)] was conducted. Data on social outcome following surgery were extracted and analyzed.

RESULTS

Social functioning was not a primary outcome measure in the reviewed article. The literature is incomplete and inconclusive on this variable, however from the reported data, there is some evidence that DBS has the potential to improve social functioning.

CONCLUSIONS

More systematic and detailed data gathering and reporting on social outcome with longer follow-ups are needed to evaluate more exhaustively the role of DBS in refractory psychiatric disorders.

Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome

The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for DBS. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic ventral nuclear group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.

Toward a Symptom-Guided Neurostimulation for Gilles de la Tourette Syndrome

Therapy resistance of approximately one-third of patients with Gilles de la Tourette syndrome (GTS) requires consideration of alternative therapeutic interventions. This article provides a condensed review of the invasive and non-invasive stimulation techniques that have been applied, to date, for treatment and investigation of GTS. Through this perspective and short review, the article discusses potential novel applications for neurostimulation techniques based on a symptom-guided approach. The concept of considering the physiological basis of specific symptoms when using stimulation techniques will provide a platform for more effective non-pharmacological neuromodulation of symptoms in GTS.

Deep Brain Stimulation for Tourette's Syndrome: The Case for Targeting the Thalamic Centromedian-Parafascicular Complex

Tourette’s syndrome (TS) is a neurologic condition characterized by both motor and phonic tics and is typically associated with psychiatric comorbidities, including obsessive-compulsive disorder/behavior and attention-deficit hyperactivity disorder, and can be psychologically and socially debilitating. It is considered a disorder of the cortico–striato–thalamo–cortical circuitry, as suggested by pathophysiology studies and therapeutic options. Among these, deep brain stimulation (DBS) of the centromedian–parafascicular nucleus (CM-Pf) of the thalamus is emerging as a valuable treatment modality for patients affected by severe, treatment-resistant TS. Here, we review the most recent experimental evidence for the pivotal role of CM-Pf in the pathophysiology of TS, discuss potential mechanisms of action that may mediate the effects of CM-Pf DBS in TS, and summarize its clinical efficacy.

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.

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.

Bilateral globus pallidus stimulation for severe Tourette's syndrome: a double-blind, randomised crossover trial

BACKGROUND

Deep brain stimulation (DBS) has been proposed as a treatment option for severe Tourette's syndrome on the basis of findings from open-label series and small double-blind trials. We aimed to further assess the safety and efficacy of bilateral globus pallidus internus (GPi) DBS in patient's with severe Tourette's syndrome.

METHODS

In a randomised, double-blind, crossover trial, we recruited eligible patients (severe medically refractory Tourette's syndrome, age ≥20 years) from two clinics for tertiary movement disorders in the UK. Enrolled patients received surgery for GPi DBS and then were randomly assigned in a 1:1 ratio (computer-generated pairwise randomisation according to order of enrolment) to receive either stimulation on-first or stimulation off-first for 3 months, followed by a switch to the opposite condition for a further 3 month period. Patients and rating clinicians were masked to treatment allocation; an unmasked clinician was responsible for programming the stimulation. The primary endpoint was difference in Yale Global Tic Severity Scale (YGTSS) total score between the two blinded conditions, assessed with repeated measures ANOVA, in all patients who completed assessments during both blinded periods. After the end of the blinded crossover phase, all patients were offered continued DBS and continued to have open-label stimulation adjustments and objective assessments of tic severity until database lock 1 month after the final patient's final trial-related visit. This trial is registered with ClinicalTrials.gov, number NCT01647269.

FINDINGS

Between Nov 5, 2009, and Oct 16, 2013, we enrolled 15 patients (11 men, four women; mean age 34·7 years [SD 10·0]). 14 patients were randomly assigned and 13 completed assessments in both blinded periods (seven in the on-first group, six in the off-first group). Mean YGTSS total score in these 13 patients was 87·9 (SD 9·2) at baseline, 80·7 (SD 12·0) for the off-stimulation period, and 68·3 (SD 18·6) for the on-stimulation period. Pairwise comparisons in YGTSS total scores after Bonferroni correction were significantly lower at the end of the on-stimulation period compared with the off-stimulation period, with a mean improvement of 12·4 points (95% CI 0·1-24·7, p=0·048), equivalent to a difference of 15·3% (95% CI 5·3-25·3). All 15 patients received stimulation in the open-label phase. Overall, three serious adverse events occurred (two infections in DBS hardware at 2 and 7 weeks postoperatively, and one episode of deep-brain-stimulation-induced hypomania during the blinded on-stimulation period); all three resolved with treatment.

INTERPRETATION

GPi stimulation led to a significant improvement in tic severity, with an overall acceptable safety profile. Future research should concentrate on identifying the most effective target for DBS to control both tics and associated comorbidities, and further clarify factors that predict individual patient response.

FUNDING

UK National Health Service.

Tourette Syndrome research highlights 2014

About 200 journal articles reported research on Tourette syndrome and other tic disorders in 2014. Here we briefly summarize a few of the reports that seemed most important or interesting, ranging from animal models to human studies. Readers can comment on our choices or provide their own favorites using the tools on the online article.

Uncommon applications of deep brain stimulation in hyperkinetic movement disorders

Background

In addition to the established indications of tremor and dystonia, deep brain stimulation (DBS) has been utilized less commonly for several hyperkinetic movement disorders, including medication-refractory myoclonus, ballism, chorea, and Gilles de la Tourette (GTS) and tardive syndromes. Given the lack of adequate controlled trials, it is difficult to translate published reports into clinical use. We summarize the literature, draw conclusions regarding efficacy when possible, and highlight concerns and areas for future study.

Methods

A Pubmed search was performed for English-language articles between January 1980 and June 2014. Studies were selected if they focused primarily on DBS to treat the conditions of focus.

Results

We identified 49 cases of DBS for myoclonus-dystonia, 21 for Huntington's disease, 15 for choreacanthocytosis, 129 for GTS, and 73 for tardive syndromes. Bilateral globus pallidus interna (GPi) DBS was the most frequently utilized procedure for all conditions except GTS, in which medial thalamic DBS was more common. While the majority of cases demonstrate some improvement, there are also reports of no improvement or even worsening of symptoms in each condition. The few studies including functional or quality of life outcomes suggest benefit. A limited number of studies included blinded on/off testing. There have been two double-blind controlled trials performed in GTS and a single prospective double-blind, uncontrolled trial in tardive syndromes. Patient characteristics, surgical target, stimulation parameters, and duration of follow-up varied among studies.

Discussion

Despite these extensive limitations, the literature overall supports the efficacy of DBS in these conditions, in particular GTS and tardive syndromes. For other conditions, the preliminary evidence from small studies is promising and encourages further study.