Deep Brain Stimulation for Tourette-Syndrome: A Systematic Review and Meta-Analysis

Neuroanatomical considerations for optimizing thalamic deep brain stimulation in Tourette syndrome

OBJECTIVE

Deep brain stimulation (DBS) of the centromedian thalamic nucleus has been reportedly used to treat severe Tourette syndrome, yielding promising outcomes. However, it remains unclear how DBS electrode position and stimulation parameters modulate the specific area and related networks. The authors aimed to evaluate the relationships between the anatomical location of stimulation fields and clinical responses, including therapeutic and side effects.

METHODS

The authors collected data from 8 patients with Tourette syndrome who were treated with DBS. The authors selected the active contact following threshold tests of acute side effects and gradually increased the stimulation intensity within the therapeutic window such that acute and chronic side effects could be avoided at each programming session. The patients were carefully interviewed, and stimulation-induced side effects were recorded. Clinical outcomes were evaluated using the Yale Global Tic Severity Scale, the Yale-Brown Obsessive-Compulsive Scale, and the Hamilton Depression Rating Scale. The DBS lead location was evaluated in the normalized brain space by using a 3D atlas. The volume of tissue activated was determined, and the associated normative connective analyses were performed to link the stimulation field with the therapeutic and side effects.

RESULTS

The mean follow-up period was 10.9 ± 3.9 months. All clinical scales showed significant improvement. Whereas the volume of tissue activated associated with therapeutic effects covers the centromedian and ventrolateral nuclei and showed an association with motor networks, those associated with paresthesia and dizziness were associated with stimulation of the ventralis caudalis and red nucleus, respectively. Depressed mood was associated with the spread of stimulation current to the mediodorsal nucleus and showed an association with limbic networks.

CONCLUSIONS

This study addresses the importance of accurate implantation of DBS electrodes for obtaining standardized clinical outcomes and suggests that meticulous programming with careful monitoring of clinical symptoms may improve outcomes.

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.

Immunity and Gilles de la Tourette syndrome: A systematic review and meta-analysis of evidence for immune implications in Tourette syndrome

BACKGROUND AND PURPOSE

The neurobiology of Gilles de la Tourette syndrome (GTS) is known to involve corticostriatal loops possibly under genetic control. Less is known about possible environmental triggers of GTS. Specifically, immune-related events following possible environmental inducers have been evoked, but important controversies still exist. In this systematic review and meta-analysis, we looked for evidence in favor of such possibilities.

METHODS

We performed a systematic review and meta-analysis of all immunological data in PubMed.

RESULTS

We found large discrepancies concerning immune dysfunctions in GTS, and meta-analyzing cytokines data did not allow us to conclude there is an involvement of specific cytokines in GTS neurobiology. When looking specifically at pediatric autoimmune neuropsychiatric disorder associated with streptococcus/pediatric acute onset neuropsychiatric syndrome, we found some important evidence of a possible infectious involvement but in a limited number of studies. Our meta-analysis found an increased level of anti-streptolysin O antibodies in GTS patients, but the level of anti-DNase B antibodies was not increased.

CONCLUSIONS

Too many questions still exist to allow us to definitively reach the conclusion that there is an infectious and immunological etiology in GTS. Much work is still needed to elucidate the possible role of immunology in GTS neurobiology and to favor immunological treatment rather than classical treatment.

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.

Directional Deep Brain Stimulation for Parkinson's Disease: Results of an International Crossover Study With Randomized, Double-Blind Primary Endpoint

OBJECTIVE

Published reports on directional deep brain stimulation (DBS) have been limited to small, single-center investigations. Therapeutic window (TW) is used to describe the range of stimulation amplitudes achieving symptom relief without side effects. This crossover study performed a randomized double-blind assessment of TW for directional and omnidirectional DBS in a large cohort of patients implanted with a DBS system in the subthalamic nucleus for Parkinson's disease.

MATERIALS AND METHODS

Participants received omnidirectional stimulation for the first three months after initial study programming, followed by directional DBS for the following three months. The primary endpoint was a double-blind, randomized evaluation of TW for directional vs. omnidirectional stimulation at three months after initial study programming. Additional data recorded at three- and six-month follow-ups included stimulation preference, therapeutic current strength, Unified Parkinson's Disease Rating Scale (UPDRS) part III motor score, and quality of life.

RESULTS

The study enrolled 234 subjects (62 ± 8 years, 33% female). TW was wider using directional stimulation in 183 of 202 subjects (90.6%). The mean increase in TW with directional stimulation was 41% (2.98 ± 1.38 mA, compared to 2.11 ± 1.33 mA for omnidirectional). UPDRS part III motor score on medication improved 42.4% at three months (after three months of omnidirectional stimulation) and 43.3% at six months (after three months of directional stimulation) with stimulation on, compared to stimulation off. After six months, 52.8% of subjects blinded to stimulation type (102/193) preferred the period with directional stimulation, and 25.9% (50/193) preferred the omnidirectional period. The directional period was preferred by 58.5% of clinicians (113/193) vs. 21.2% (41/193) who preferred the omnidirectional period.

CONCLUSION

Directional stimulation yielded a wider TW compared to omnidirectional stimulation and was preferred by blinded subjects and clinicians.

Effectiveness of Low-Frequency Pallidal Deep Brain Stimulation at 65 Hz in Tourette Syndrome

OBJECTIVES

Pallidal deep brain stimulation (DBS) for refractory Tourette syndrome (TS) is often applied using a high frequency. The effectiveness of low-frequency long-term stimulation is unknown. We aimed to evaluate the clinical efficacy of low-frequency DBS applied to the globus pallidus pars internus (GPi) at 65 Hz for the treatment of TS, with long-term follow-up, to provide data for the optimization of stimulation parameters.

MATERIALS AND METHODS

A total of six patients with refractory TS were implanted with electrodes in the GPi and were assigned to receive low-frequency (65 Hz) DBS programming. Assessments were performed pre-DBS and at 3, 12, and a median of 34 (range 26-48) months post-DBS. The primary outcome was tic severity, as assessed by the Yale Global Tic Severity Scale (YGTSS), and the secondary outcomes were comorbid behavioral disorders, mood, functioning, and quality of life.

RESULTS

We noted significant differences in the YGTSS scores between the baseline and the post-DBS follow-ups (p = 0.01). At the final follow up, four of six (66.6%) patients had a greater than 50% reduction in the YGTSS score, whereas the remaining two patients showed a mild worsening of tic severity. The secondary outcome measures also showed remarkable improvements in associated behavioral disorders, mood, functioning, and quality of life. Stimulation-induced adverse effects were not reported, although a device-related complication (an uncomfortable feeling in the neck) occurred in 1 patient.

CONCLUSIONS

The results of this study indicated that low-frequency DBS represents an effective and practical treatment for refractory TS with comparable efficacy to high-frequency DBS.

Randomized double-blind sham-controlled trial of thalamic versus GPi stimulation in patients with severe medically refractory Gilles de la Tourette syndrome

BACKGROUND

There are still no sufficient data regarding the use of deep brain stimulation (DBS) in Gilles de la Tourette syndrome (GTS) and no agreement on optimal target.

OBJECTIVE

To compare efficacy and safety of bilateral DBS of thalamus (centromedian-ventro-oral internus, CM-Voi) versus posteroventral lateral globus pallidus internus (pvl GPi)) versus sham stimulation, and baseline in severe medically refractory GTS.

METHODS

In this randomized double-blind sham stimulation-controlled trial (RCT), 10 patients (3 women, mean age = 29.4 ± 10.2 SD, range 18-47) underwent three blinded periods each lasting three months including (i) sham, (ii) pvl GPi (on-GPi), and (iii) thalamic stimulation (on-thal) followed by an open uncontrolled long-term follow-up (up to 9 years) with individually determined target and stimulation settings.

RESULTS

Nine patients completed the RCT. At group level, on-GPi - but not on-thal - resulted in a significant tic reduction compared to baseline, but had no effect on premonitory urges and psychiatric comorbidities. Direct comparisons of targets resulted in inconsistent or negative (compared to sham) findings. During follow-up, we found no improvement of tics, comorbidities, and quality of life at group level, however, single patients benefitted continuously from thalamic DBS. At last follow-up 89.9 months (mean) after surgery, 50% of patients had discontinued DBS. Hardware infections occurred in 3/10 patients.

CONCLUSION

Our data suggest that the initial effect of pvl GPi DBS is superior to thalamic (CM-Voi) DBS. While half of the patients discontinued treatment, single patients benefitted from thalamic DBS even after years. It is likely that outcome is influenced by various factors beyond the mere change in tic severity.

Aripiprazole for the treatment of Tourette syndrome

Introduction: Tourette syndrome (TS) is a neurodevelopmental disorder characterized by multiple tics which often persisting in forms of different severity throughout adult life. The prevalence of neuropsychiatric co-morbidity in patients with TS is high. Treatment of TS can involve pharmacological, behavioral, or, in rare cases, surgical therapies. Over the last two decades there has been growing interest in the use of aripiprazole, a novel partial dopamine receptor agonist, as a promising anti-tic agent.Areas covered: The authors reviewed the available literature evaluating the role of aripiprazole in the treatment of TS and other tic disorders in both children and adults. This includes data from five randomized controlled trials (RCTs) and eleven open-label studies.Expert opinion: There is moderate quality evidence supporting the use of aripiprazole in reducing tic severity in children and adolescents, however there is a lack of robust evidence evaluating its use in adults, despite expert consensus. Overall, it appears that aripiprazole is a safe and effective treatment for tics. Further large scale RCTs assessing the long-term efficacy and safety of aripiprazole in the treatment of tics are warranted, especially in adult populations with TS.

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.

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.

Medical Students' Knowledge and Perception of Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) is a well-established neurosurgical procedure commonly used in movement and psychiatric disorders. Its widespread clinical implementation, however, may not be commensurate with medical education. No current assessment of medical student's understanding of DBS as a treatment option for indicated conditions is available, potentially threatening the availability of DBS to future patients. The aim of the present study is to explore the current knowledge and attitudes of medical students toward DBS as a treatment modality.

METHODS

A total of 65 medical students at Virginia Tech Carilion School of Medicine were surveyed regarding their knowledge of DBS. The survey consisted of a 25-item questionnaire including a demographic section and 3 separate inventories designed to assess bias, knowledge, and self-assessment of knowledge specific to DBS therapy. Students in pre-clinical and clinical years were analyzed separately to describe changes in knowledge or attitude associated with clinical exposure to DBS. Comparisons were analyzed using t tests, ANOVA, and Pearson correlations.

RESULTS

Of surveyed students, 36% were unsure of the FDA approval status of DBS treatment; 65% of students believed they had not been adequately educated about DBS and its utility; and 10.6% of students believed that DBS is likely associated with severe adverse effects and/or brain damage. The overall baseline attitudes of students toward DBS were positive. There was no observed difference between surveyed pre-clinical and clinical students, highlighting a lack of exposure throughout the clinical years of medical school education.

CONCLUSION

Although DBS is an effective treatment modality for various conditions, current education is non-commensurate with its application, which can negatively impact awareness and understanding for its implications by medical professionals. In order to better serve patients who may benefit from DBS, medical curricula must change to educate future physicians on the benefit of this intervention.

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.

Deep Brain Stimulation for Refractory Tourette Syndrome: Electrode Position and Clinical Outcome

The efficacy of deep brain stimulation (DBS) for refractory Tourette syndrome (TS) is accepted, but whether the efficacy of DBS treatment in the Japanese population is equivalent to those reported internationally and whether adverse effects are comparable are not yet known. This study evaluated the clinical practice and outcome of DBS for TS in a Japanese institution. This study included 25 consecutive patients with refractory TS treated with thalamic centromedian-parafascicular nucleus DBS. The severity of tics was evaluated with the Yale Global Tic Severity Scale (YGTSS) before surgery, at 1 year after surgery, and at the last follow-up of 3 years or more after surgery. The occurrence of adverse events, active contact locations, and stimulation conditions were also evaluated. YGTSS tic severity score decreased by average 45.2% at 1 year, and by 56.6% at the last follow-up. The reduction was significant for all aspects of the scores including motor tics, phonic tics, and impairment. The mean coordinates of active contacts were 7.62 mm lateral to the midline, 3.28 mm posterior to the midcommissural point, and 3.41 mm above anterior commissure–posterior commissure plane. Efficacy and stimulation conditions were equivalent to international reports. The stimulation-induced side effects included dysarthria (32.0%) and paresthesia (12.0%). Device infection occurred in three patients (12.0%) as a surgical complication. The DBS device was removed because of infection in two patients. DBS is an effective treatment for refractory TS, although careful indication is necessary because of the surgical risks and unknown long-term outcome.

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.

Sustained Relief after Pallidal Stimulation Interruption in Tourette's Syndrome Treated with Simultaneous Capsulotomy

INTRODUCTION

Globus pallidus internus (GPi) deep brain stimulation (DBS) combined with anterior capsulotomy offers a promising treatment option for severe medication-refractory cases of Tourette's syndrome (TS) with psychiatric comorbidities. Several patients treated with this combined surgery experienced sustained relief after discontinuation of stimulation over the course of treatment.

METHODS

Retrospectively, the medical records and clinical outcomes were reviewed of 8 patients (6 men; 2 women with mean age of 20.3 years) who had undergone bilateral GPi-DBS combined with anterior capsulotomy for medically intractable TS and psychiatric comorbidities. All patients had experienced an accidental interruption or intentional withdrawal of pallidal stimulation during treatment.

RESULTS

The widespread clinical benefits achieved during the combined treatment were fully maintained after intentional or accidental DBS discontinuation. The improvement in overall tic symptoms achieved was on average 78% at the follow-up or close to the DBS discontinuation, while it was 83% at last follow-up (LFU). At LFU, most patients had functionally recovered; exhibited only mild tics; displayed minor or no obsessive-compulsive disorder symptoms, anxiety, or depression; and experienced a much better quality of life.

CONCLUSION

Bilateral GPi-DBS combined with anterior capsulotomy appears to result in marked and sustained improvements in TS symptoms and psychiatric comorbidities, which are fully maintained over time, even without pallidal stimulation.

Deep brain stimulation: a review of the open neural engineering challenges

OBJECTIVE

Deep brain stimulation (DBS) is an established and valid therapy for a variety of pathological conditions ranging from motor to cognitive disorders. Still, much of the DBS-related mechanism of action is far from being understood, and there are several side effects of DBS whose origin is unclear. In the last years DBS limitations have been tackled by a variety of approaches, including adaptive deep brain stimulation (aDBS), a technique that relies on using chronically implanted electrodes on 'sensing mode' to detect the neural markers of specific motor symptoms and to deliver on-demand or modulate the stimulation parameters accordingly. Here we will review the state of the art of the several approaches to improve DBS and summarize the main challenges toward the development of an effective aDBS therapy.

APPROACH

We discuss models of basal ganglia disorders pathogenesis, hardware and software improvements for conventional DBS, and candidate neural and non-neural features and related control strategies for aDBS.

MAIN RESULTS

We identify then the main operative challenges toward optimal DBS such as (i) accurate target localization, (ii) increased spatial resolution of stimulation, (iii) development of in silico tests for DBS, (iv) identification of specific motor symptoms biomarkers, in particular (v) assessing how LFP oscillations relate to behavioral disfunctions, and (vi) clarify how stimulation affects the cortico-basal-ganglia-thalamic network to (vii) design optimal stimulation patterns.

SIGNIFICANCE

This roadmap will lead neural engineers novel to the field toward the most relevant open issues of DBS, while the in-depth readers might find a careful comparison of advantages and drawbacks of the most recent attempts to improve DBS-related neuromodulatory strategies.

Current Management of Tics and Tourette Syndrome: Behavioral, Pharmacologic, and Surgical Treatments

Tourette syndrome is a heterogeneous neurobehavioral disorder manifested by childhood-onset motor and phonic tics, often accompanied by a variety of behavioral comorbidities, including attention deficit and obsessive compulsive disorder. Treatment must be tailored to the needs and goals of the individual patients and their families. All patients should receive education on the condition and, if possible, engage behavioral therapy targeted towards tics and/or comorbidities. Pharmacological therapies, such as alpha agonists, topiramate, and vesicular monoamine transport type 2 inhibitors, are generally used as first-line therapies in patients with troublesome tics that are not controlled by behavioral therapy or when the latter is not available or accessible. Botulinum toxin injections can be used in patients with bothersome focal tics. Second-line therapy includes antipsychotics, such as fluphenazine, aripiprazole, risperidone, and ziprasidone. These medications are generally efficacious but carry the risk of metabolic syndrome, tardive dyskinesia, and other side effects. Much more research is needed before novel therapies such as cannabis-derived products or transcranial magnetic stimulation can be recommended. There is promise in ongoing clinical trials with D1 receptor antagonist ecopipam and other experimental therapeutics. Patients with tics that are refractory to conventional treatments may be candidates for deep brain stimulation, but further studies are needed to determine the optimal target selection.

Paediatric deep brain stimulation: ethical considerations in malignant Tourette syndrome

Gilles de la Tourette syndrome (TS) is a childhood neuropsychiatric disorder characterised by the presence of motor and vocal tics. Patients with malignant TS experience severe disease sequelae; risking morbidity and mortality due to tics, self-harm, psychiatric comorbidities and suicide. By definition, those cases termed 'malignant' are refractory to all conventional psychiatric and pharmacological regimens. In these instances, deep brain stimulation (DBS) may be efficacious. Current 2015 guidelines recommend a 6-month period absent of suicidal ideation before DBS is offered to patients with TS. We therefore wondered whether it may be ethically justifiable to offer DBS to a minor with malignant TS. We begin with a discussion of non-maleficence and beneficence. New evidence suggests that suicide risk in young patients with TS has been underestimated. In turn, DBS may represent an invaluable opportunity for children with malignant TS to secure future safety, independence and fulfilment. Postponing treatment is associated with additional risks. Ultimately, we assert this unique risk-benefit calculus justifies offering DBS to paediatric patients with malignant TS. A multidisciplinary team of clinicians must determine whether DBS is in the best interest of their individual patients. We conclude with a suggestion for future TS-DBS guidelines regarding suicidal ideation. The importance of informed consent and assent is underscored.

Anatomical Characterization of the Human Structural Connectivity between the Pedunculopontine Nucleus and Globus Pallidus via Multi-Shell Multi-Tissue Tractography

Background and objectives: The internal (GPi) and external segments (GPe) of the globus pallidus represent key nodes in the basal ganglia system. Connections to and from pallidal segments are topographically organized, delineating limbic, associative and sensorimotor territories. The topography of pallidal afferent and efferent connections with brainstem structures has been poorly investigated. In this study we sought to characterize in-vivo connections between the globus pallidus and the pedunculopontine nucleus (PPN) via diffusion tractography. Materials and Methods: We employed structural and diffusion data of 100 subjects from the Human Connectome Project repository in order to reconstruct the connections between the PPN and the globus pallidus, employing higher order tractography techniques. We assessed streamline count of the reconstructed bundles and investigated spatial relations between pallidal voxels connected to the PPN and pallidal limbic, associative and sensorimotor functional territories. Results: We successfully reconstructed pallidotegmental tracts for the GPi and GPe in all subjects. The number of streamlines connecting the PPN with the GPi was greater than the number of those joining it with the GPe. PPN maps within pallidal segments exhibited a distinctive spatial organization, being localized in the ventromedial portion of the GPi and in the ventral-anterior portion in the GPe. Regarding their spatial relations with tractography-derived maps of pallidal functional territories, the highest value of percentage overlap was noticed between PPN maps and the associative territory. Conclusions: We successfully reconstructed the anatomical course of the pallidotegmental pathways and comprehensively characterized their topographical arrangement within both pallidal segments. PPM maps were localized in the ventromedial aspect of the GPi, while they occupied the anterior pole and the most ventral portion of the GPe. A better understanding of the spatial and topographical arrangement of the pallidotegmental pathways may have pathophysiological and therapeutic implications in movement disorders.

Lead Repositioning Guided by Both Physiology and Atlas Based Targeting in Tourette Deep Brain Stimulation

Background:

The centromedian (CM) region of the thalamus is a common target for deep brain stimulation (DBS) treatment for Tourette Syndrome (TS). However, there are currently no standard microelectrode recording or macrostimulation methods to differentiate CM thalamus from other nearby structures and nuclei.

Case Report:

Here we present a case of failed conventional stereotactic targeting in TS DBS. Postoperative local field potential recordings (LFPs) showed features including beta power desynchronization during voluntary movement and thalamo-cortical phase amplitude coupling at rest. These findings suggested that the DBS lead was suboptimally placed in the ventral intermediate (VIM) nucleus of the thalamus rather than the intended CM region. Due to a lack of clinical improvement in tic severity scales three months following the initial surgery, the patient underwent lead revision surgery. Slight repositioning of the DBS leads resulted in a remarkably different clinical outcome. Afterwards, LFPs revealed less beta desynchronization and disappearance of the thalamo-cortical phase amplitude coupling. Follow-up clinical visits documented improvement of the patient’s global tic scores.

Discussion:

This case provides preliminary evidence that combining physiology with atlas based targeting may possibly enhance outcomes in some cases of Tourette DBS. A larger prospective study will be required to confirm these findings.

Highlight:

This report demonstrates a case of failed centromedian nucleus region deep brain stimulation (DBS). We observed suboptimal tic improvement several months following DBS surgery and subsequent lead revision improved the outcome. The neurophysiology provided an important clue suggesting the possibility of suboptimally placed DBS leads. Repeat LFPs during lead revision revealed less beta desynchronization and disappearance of the thalamo-cortical phase amplitude coupling. There was improvement in tic outcome following slight repositioning during bilateral DBS lead revision. This case provides preliminary evidence supporting the use of physiology to augment the atlas based targeting of Tourette DBS cases.

Deep brain stimulation lead removal in Tourette syndrome

INTRODUCTION

Tourette syndrome (TS) is a complex neuropsychiatric disorder. A small percentage of individuals with TS can experience persistent severe, refractory, and impairing tics. Deep brain stimulation (DBS) has been increasingly used for symptom management, especially in these settings. In this article, we aim to evaluate the rate and the reasons for removal of DBS hardware in TS patients.

METHODS

Data was analyzed from patients enrolled in the Tourette Association of America's International Tourette Syndrome Registry and Database.

RESULTS

Fifteen of 269 (5.6%) patients required removal of their DBS systems. The mean age at explantation was 33.8 years. In these cases we observed a rate of 1.9 explantations per year of follow up from implantation. None of the removals took place in the immediate post-operative period. Infection was the most common cause (46.7%). Only one patient received explantation for tic resolution. There were no significant associations between explantation and the presence of specific psychiatric comorbidities, including OCD, depression, anxiety, or ADHD.

DISCUSSION

The rate of removal of 5.6% was lower than the previously reported rate in the TS DBS literature. Infections accounted for nearly half of the TS DBS explantations in this cohort. There was no relationship to psychiatric comorbidities.

A Review of the Current Treatment of Tourette Syndrome

Tourette syndrome is a hyperkinetic movement disorder that presents before age 18 years and involves motor and phonic tics that may present with a wide range of severity. The severity and presentation of tics in an individual may fluctuate over time. Tourette syndrome may affect social relationships and school attendance, and may result in depression. Comorbidities are common, with attention-deficit/hyperactivity disorder and obsessive-compulsive disorder being most common. The literature supporting optimal treatment is limited but provides a framework for clinical decision-making. The focus of this review is to discuss the symptoms and possible causes of Tourette syndrome and current non-pharmacologic and pharmacologic treatment options, to help practitioners optimize care for pediatric patients with this disease.

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.

Modulation of Fibers to Motor Cortex during Thalamic DBS in Tourette Patients Correlates with Tic Reduction

Probabilistic tractography in Tourette syndrome (TS) patients have shown an alteration in the connectivity of the primary motor cortex and supplementary motor area with the striatum and thalamus, suggesting an abnormal connectivity of the cortico-striatum-thalamocortical-pathways in TS. Deep brain stimulation (DBS) of the centromedian nucleus–nucleus ventrooralis internus (CM-Voi complex) in the thalamus is an effective treatment for refractory TS patients. We investigated the connectivity of activated fibers from CM-Voi to the motor cortex and its correlation between these projections and their clinical outcome. Seven patients with TS underwent CM-Voi-DBS surgery and were clinically evaluated preoperatively and six months postoperatively. We performed diffusion tensor imaging to display the activated fibers projecting from the CM-Voi to the different motor cortex regions of interest. These analyses showed that the extent of tic reduction during DBS is associated with the degree of stimulation-dependent connectivity between CM-Voi and the motor cortex, and in particular, an increased density of projections to the presupplementary motor area (preSMA). Non-responder patients displayed the largest amount of active fibers projecting into cortical areas other than motor cortex compared to responder patients. These findings support the notion that an abnormal connectivity of thalamocortical pathways underlies TS, and that modulation of these circuits through DBS could restore the function and reduce symptoms.

Deep Brain Stimulation for Gilles de la Tourette Syndrome: Toward Limbic Targets

Gilles de la Tourette syndrome (GTS) is a complex neurodevelopmental disorder characterized by tics and, frequently, psychiatric and behavioral comorbidities. Above all, obsessive compulsive disorder/behavior (OCD/OCB) influences the clinical picture and has a severe impact on quality of life, eventually more than the tics themselves. Deep brain stimulation (DBS) is an effective therapy in selected, refractory cases. Clinical response to DBS may vary according to the clinical picture, comorbidities, and to the anatomical target. This retrospective study compares the results obtained from DBS in the ventralis oralis/centromedian-parascicular nucleus of the thalamus (Voi-Cm/Pf) (41 patients) and antero-medial Globus Pallidus internus (am-GPi) (14 patients), evaluating clinical response over time by means of Yale Global Tic Severity Scale (YGTSS) and Yale–Brown Obsessive-Compulsive Scale (YBOCS) scores over a period of 48 months. A significant and stable improvement in the YGTSS and YBOCS has been obtained in both groups (p < 0.001). There was a significant difference in YBOCS improvement over time between the am-GPi group and the Voi-Cm/Pf group, indicating a better and faster control of OCD/OCB symptoms in the former group. The ratio of hardware removal was 23% and limited to 13 patients in the Voi-Cm/Pf group. These results confirm that DBS is an effective therapy in treating GTS and suggest that the am-GPi might be superior to Voi-Cm/Pf in alleviating comorbid OCD/OCB.

Interventions for tic disorders: An updated overview of systematic reviews and meta analyses

To conduct an updated overview of systematic reviews (SRs) summarizing the efficacy and safety of various strategies used to treat tic disorders (TDs) in children. We searched the Cochrane Library, PubMed, EMBASE, and relevant reference lists for articles published between the search deadline from our last overview and April 2019 and included 16 SRs. The results presented that antipsychotics, a2-adrenergic receptor agonists, and HRT/CBIT still appeared to be the most robust evidence-based options for the treatment of TDs. Compared with our last overview, more robust evidence showed that aripiprazole and acupuncture was effective treatment in treating children TDs, and DBS for medication-refractory and severely affected patients. In addition, physical activity or exercise may be promising treatments, and the clonidine adhesive patch is an effective, safe, and convenient treatment option for TDs. Moreover, methylphenidate, guanfacine, and desipramine appeared to reduce ADHD symptoms in children with tics. However, no research studies have examined HRT/CBIT alone compared with HRT/CBIT in combination with medication. More high-quality clinical trials comparing different interventions for TDs including economic evaluations should be encouraged.

Anterior Limb of Internal Capsule and Bed Nucleus of Stria Terminalis Stimulation for Gilles de la Tourette Syndrome with Obsessive-Compulsive Disorder in Adolescence: A Case of Success

Gilles de la Tourette syndrome (GTS) is a neurobehavioral disorder comprising motor and vocal tics. In most cases it is associated with other disorders such as obsessive-compulsive disorder (OCD). In refractory cases deep brain stimulation (DBS) is a valid treatment option. This paper describes the case of a 15-year-old adolescent with an extremely refractory GTS with associated OCD. The patient developed catatonia associated with OCD, which partially remitted after electroconvulsive therapy. At the peak of the disease the Yale Global Tic Severity Scale (YGTSS) was 100 and the patient required sedation and intubation. All medical treatment options were unsuccessful. Bilateral DBS of the anterior limb of internal capsule (ALIC)/bed nucleus of stria terminalis (BST) region was performed, using a target below the BST and a trajectory through the ALIC, with stimulation of contacts 0 and 3. Two weeks after surgery sedatives were suspended and the patient was successfully extubated. One year after surgery the patient reached a YGTSS of 19, representing an 81% improvement. OCD completely resolved. Adverse events were a superficial infection and weight gain. In conclusion, this ALIC/BST stimulation appears to have been an effective and safe treatment for GTS with OCD in this case. Young age should not be an exclusion criterion for DBS in severe GTS and OCD. Further studies should be pursued for this target.

The anterior limb of the internal capsule: Anatomy, function, and dysfunction

The last two decades have seen a re-emergence of neurosurgery for severe, refractory psychiatric diseases, largely due to the advent of more precise and safe operative techniques. Nevertheless, the optimal targets for these surgeries remain a matter of debate, and are often grandfathered from experiences in the late 20th century. To better explore the rationale for one target in particular - the anterior limb of the internal capsule (ALIC) - we comprehensively reviewed all available literature on its role in the pathophysiology and treatment of mental illness. We first provide an overview of its functional anatomy, followed by a discussion on its role in several prevalent psychiatric diseases. Given its structural integration into the limbic system and involvement in a number of cognitive and emotional processes, the ALIC is a robust target for surgical treatment of refractory psychiatric diseases. The advent of novel neuroimaging techniques, coupled with image-guided therapeutics and neuromodulatory treatments, will continue to enable study on the ALIC in mental illness.

[Tourette syndrome: Research challenges to improve clinical practice]

Tourette syndrome is a neurodevelopmental disorder which is characterized by the presence of motor and phonic tics. These tics are generally more prevalent in childhood. Tics typically reach their maximum severity before puberty, around age 10 to 12. In most patients, tic severity usually decreases during late adolescence and adulthood. However, this is not true for all individuals. To date, the developmental trajectory leading to the persistence of tics into adulthood is still poorly understood. There are very few markers that can predict the evolution of tic symptoms from childhood to adulthood. Yet, while we cannot cure Tourette syndrome, it is possible to reduce tic severity with various treatments. The most common treatments are pharmacotherapy and behavioral and cognitive-behavioral therapy. However, there appears to be a limit to the proportion of tics that can be treated, since most treatments offer an average reduction in tics of no more than 50%. Thus, at first, this article reviews recent advances in treatment and symptom progression. Next, we propose some lines of research to improve the management and treatment of people with Tourette syndrome.

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: current challenges and future directions

The clinical use of deep brain stimulation (DBS) is among the most important advances in the clinical neurosciences in the past two decades. As a surgical tool, DBS can directly measure pathological brain activity and can deliver adjustable stimulation for therapeutic effect in neurological and psychiatric disorders correlated with dysfunctional circuitry. The development of DBS has opened new opportunities to access and interrogate malfunctioning brain circuits and to test the therapeutic potential of regulating the output of these circuits in a broad range of disorders. Despite the success and rapid adoption of DBS, crucial questions remain, including which brain areas should be targeted and in which patients. This Review considers how DBS has facilitated advances in our understanding of how circuit malfunction can lead to brain disorders and outlines the key unmet challenges and future directions in the DBS field. Determining the next steps in DBS science will help to define the future role of this technology in the development of novel therapeutics for the most challenging disorders affecting the human brain.

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.

Trichotillomania is more related to Tourette disorder than to obsessive-compulsive disorder

OBJECTIVE

Trichotillomania (TTM) is characterized by the pulling out of one's hair. TTM was classified as an impulse control disorder in DSM-IV, but is now classified in the obsessive-compulsive related disorders section of DSM-5. Classification for TTM remains an open question, especially considering its impact on treatment of the disorder. In this review, we questioned the relation of TTM to tic disorder and obsessive-compulsive disorder (OCD).

METHOD

We reviewed relevant MEDLINE-indexed articles on clinical, neuropsychological, neurobiological, and therapeutic aspects of trichotillomania, OCD, and tic disorders.

RESULTS

Our review found a closer relationship between TTM and tic disorder from neurobiological (especially imaging) and therapeutic standpoints.

CONCLUSION

We sought to challenge the DSM-5 classification of TTM and to compare TTM with both OCD and tic disorder. Some discrepancies between TTM and tic disorders notwithstanding, several arguments are in favor of a closer relationship between these two disorders than between TTM and OCD, especially when considering implications for therapy. This consideration is essential for patients.

Efficacy and safety of traditional Chinese medicine for Tourette's syndrome: A meta-analysis of randomized controlled trials

BACKGROUND

Traditional Chinese medicine (TCM) has been widely used in the treatment of Tourette's Syndrome (TS). However, the efficacy and safety of TCM in treating TS are mixed across studies. This is a meta-analysis of studies on the efficacy and safety of TCM compared to placebo and Western medicine (WM).

METHODS

PubMed, Cochrane Library, PsycINFO, Chinese National Knowledge Infrastructure, SinoMed, and WanFang databases were systematically searched from inception date to October 16, 2018. Randomized Controlled Trials (RCTs) on the efficacy and safety of TCM alone or TCM + WM combination for TS were included.

RESULTS

A total of 15 studies comprising 21 treatment trials (n = 2824) were included. TCM alone was more efficacious than placebo in terms of response rate (Relative Risk, RR: 1.96, 95% CI: 1.55-2.47, P < 0.01, I² = 45 %) and the change in the Yale Global Tic Severity Scale total score (Standard mean difference, SMDs: -0.67, 95% CI: -0.81, -0.53, P < 0.01, I² = 0 %). The results remained positive when TCM alone was compared with WM alone (RR: 1.06, 95% CI: 1.00-1.12, P = 0.03, I² = 29 %), and when TCM + WM were compared with WM alone (RR: 1.24, 95% CI: 1.08-1.43, P < 0.01, I² = 0 %). Adverse drug reactions were more frequent in WM than in TCM groups (P < 0.05). WM type (P = 0.02), proportion of males (P = 0.03) and trial duration (P = 0.03) were significantly associated with response rate in TS patients when comparing TCM alone with WM alone.

CONCLUSION

The results of this meta-analysis support the efficacy and safety of TCM alone and TCM + WM in TS patients.

Treatment of dystonia and tics

Treatment of dystonia and tics continues to evolve. In dystonia, while oral agents such as benzodiazepines, baclofen and anticholinergics remain in use, botulinum toxin (BoNT) continues to be regarded as the treatment of choice for focal and segmental dystonia, but new preparations are being studied. While deep brain stimulation (DBS) has typically focused on targeting the globus pallidus internus (GPi) when treating dystonia, more recent research has expanded the targets to include subthalamic nucleus (STN) and other targets. In addition to DBS, thalamotomies continue to show therapeutic benefit in focal hand dystonias. Treatment of tics includes a growing armamentarium of options besides the three FDA-approved drugs, all dopamine receptor blockers (haloperidol, pimozide and aripiprazole). Because of lower risk of adverse effects, dopamine depleters (e.g. tetrabebazine, deutetrabenazine, and valbenazine), along with novel D1 receptor antagonists, are currently studied as treatment alternatives in patients with tics. Practice guidelines for the treatment of tics and Tourette syndrome have been recently updated. Data regarding the use of DBS in treatment of tics remains relatively sparse, but international registries have expanded our understanding of the effect of stimulation at several targets.

Pallidal deep brain stimulation combined with capsulotomy for Tourette's syndrome with psychiatric comorbidity

OBJECTIVE

A current challenge is finding an effective and safe treatment for severely disabled patients with Tourette's syndrome (TS) and comorbid psychiatric disorders, in whom conventional treatments have failed. The authors aimed to evaluate the utility of globus pallidus internus deep brain stimulation (GPi-DBS) combined with bilateral anterior capsulotomy in treating these clinically challenging patients.

METHODS

The authors conducted a retrospective review of the clinical history and outcomes of 10 severely disabled patients with treatment-refractory TS and a psychiatric comorbidity, who had undergone GPi-DBS combined with bilateral anterior capsulotomy in their hospital. At the time of surgery, patients presented mainly with obsessive-compulsive disorder and affective disorders. Clinical outcome assessments of tic and psychiatric symptoms, as well as of general adaptive functioning and quality of life, were performed at the time of surgery and at 6, 12, and between 24 and 96 months postsurgery.

RESULTS

After surgery, all patients showed significant progressive improvements in tic and psychiatric symptoms, along with improvements in general adaptive functioning and quality of life. Tic alleviation reached 64% at 12 months and 77% at the last follow-up on the Yale Global Tic Severity Scale. At the final follow-up, patients had functionally recovered and displayed no or only mild tic and psychiatric symptoms. All patients tolerated treatment reasonably well, with no serious side effects.

CONCLUSIONS

GPi-DBS combined with bilateral anterior capsulotomy seems to offer major clinical benefits to severely disabled patients with otherwise treatment-refractory TS and psychiatric comorbidities.

The spectrum of involuntary vocalizations in humans: A video atlas

In clinical practice, involuntary vocalizing behaviors are typically associated with Tourette syndrome and other tic disorders. However, they may also be encountered throughout the entire tenor of neuropsychiatry, movement disorders, and neurodevelopmental syndromes. Importantly, involuntary vocalizing behaviors may often constitute a predominant clinical sign, and, therefore, their early recognition and appropriate classification are necessary to guide diagnosis and treatment. Clinical literature and video-documented cases on the topic are surprisingly scarce. Here, we pooled data from 5 expert centers of movement disorders, with instructive video material to cover the entire range of involuntary vocalizations in humans. Medical literature was also reviewed to document the range of possible etiologies associated with the different types of vocalizing behaviors and to explore treatment options. We propose a phenomenological classification of involuntary vocalizations within different categorical domains, including (1) tics and tic-like vocalizations, (2) vocalizations as part of stereotypies, (3) vocalizations as part of dystonia or chorea, (4) continuous vocalizing behaviors such as groaning or grunting, (5) pathological laughter and crying, (6) vocalizations resembling physiological reflexes, and (7) other vocalizations, for example, those associated with exaggerated startle responses, as part of epilepsy and sleep-related phenomena. We provide comprehensive lists of their associated etiologies, including neurodevelopmental, neurodegenerative, neuroimmunological, and structural causes and clinical clues. We then expand on the pathophysiology of the different vocalizing behaviors and comment on available treatment options. Finally, we present an algorithmic approach that covers the wide range of involuntary vocalizations in humans, with the ultimate goal of improving diagnostic accuracy and guiding appropriate treatment. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Spatio-temporal structure of single neuron subthalamic activity identifies DBS target for anesthetized Tourette syndrome patients

OBJECTIVE

Deep brain stimulation (DBS) of basal ganglia effectively tackles motor symptoms of movement disorders such as Tourette syndrome (TS). The precise location of target stimulation site determines the range of clinical outcome in DBS patients, and the occurrence of side-effects of DBS. DBS implant procedures currently localize stimulation target relying on a combination of pre-surgical imaging, standardized brain atlases and on-the-spot clinical tests. Here we show that temporal structure of single unit activity in subthalamic nucleus (STN) of patients affected by pure TS can contribute to identify the optimal target location of DBS.

APPROACH

Neural activity was recorded at different depths within STN with microelectrodes during DBS implant surgery. Depth specific neural features were extracted and correlated with the optimal depth for tic control.

MAIN RESULTS

We describe for the first time temporal spike patterns of single neurons from sensorimotor STN of anesthetized TS patients. A large fraction of units (31.2%) displayed intense bursting in the delta band (<4 Hz). The highest firing irregularity and hence the higher density of bursting units (42%) were found at the optimal spot for tic control. Discharge patterns irregularity and dominant oscillations frequency (but not firing rate) carried significant information on optimal target.

SIGNIFICANCE

We found single unit activity features in the STN of TS patients reliably associated to optimal DBS target site for tic control. In future works measures of firing irregularity could be integrated with current target localization methods leading to a more effective and safer DBS for TS patients.

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.

Transcending the brain: is there a cost to hacking the nervous system?

Great advancements have recently been made to understand the brain and the potential that we can extract out of it. Much of this has been centred on modifying electrical activity of the nervous system for improved physical and cognitive performance in those with clinical impairment. However, there is a risk of going beyond purely physiological performance improvements and striving for human enhancement beyond traditional human limits. Simple ethical guidelines and legal doctrine must be examined to keep ahead of technological advancement in light of the impending mergence between biology and machine. By understanding the role of modern ethics, this review aims to appreciate the fine boundary between what is considered ethically justified for current neurotechnology.

Efficacy and Safety of Deep Brain Stimulation in Tourette Syndrome: The International Tourette Syndrome Deep Brain Stimulation Public Database and Registry

Importance

Collective evidence has strongly suggested that deep brain stimulation (DBS) is a promising therapy for Tourette syndrome.

Objective

To assess the efficacy and safety of DBS in a multinational cohort of patients with Tourette syndrome.

Design, Setting, and Participants

The prospective International Deep Brain Stimulation Database and Registry included 185 patients with medically refractory Tourette syndrome who underwent DBS implantation from January 1, 2012, to December 31, 2016, at 31 institutions in 10 countries worldwide.

Exposures

Patients with medically refractory symptoms received DBS implantation in the centromedian thalamic region (93 of 163 [57.1%]), the anterior globus pallidus internus (41 of 163 [25.2%]), the posterior globus pallidus internus (25 of 163 [15.3%]), and the anterior limb of the internal capsule (4 of 163 [2.5%]).

Main Outcomes and Measures

Scores on the Yale Global Tic Severity Scale and adverse events.

Results

The International Deep Brain Stimulation Database and Registry enrolled 185 patients (of 171 with available data, 37 females and 134 males; mean [SD] age at surgery, 29.1 [10.8] years [range, 13-58 years]). Symptoms of obsessive-compulsive disorder were present in 97 of 151 patients (64.2%) and 32 of 148 (21.6%) had a history of self-injurious behavior. The mean (SD) total Yale Global Tic Severity Scale score improved from 75.01 (18.36) at baseline to 41.19 (20.00) at 1 year after DBS implantation (P < .001). The mean (SD) motor tic subscore improved from 21.00 (3.72) at baseline to 12.91 (5.78) after 1 year (P < .001), and the mean (SD) phonic tic subscore improved from 16.82 (6.56) at baseline to 9.63 (6.99) at 1 year (P < .001). The overall adverse event rate was 35.4% (56 of 158 patients), with intracranial hemorrhage occurring in 2 patients (1.3%), infection in 4 patients with 5 events (3.2%), and lead explantation in 1 patient (0.6%). The most common stimulation-induced adverse effects were dysarthria (10 [6.3%]) and paresthesia (13 [8.2%]).

Conclusions and Relevance

Deep brain stimulation was associated with symptomatic improvement in patients with Tourette syndrome but also with important adverse events. A publicly available website on outcomes of DBS in patients with Tourette syndrome has been provided.

Economic evaluation of deep-brain stimulation for Tourette's syndrome: an initial exploration

BACKGROUND

Deep-brain stimulation (DBS) can be effective in controlling medically intractable symptoms of Tourette's syndrome (TS). There is no evidence to date, though, of the potential cost-effectiveness of DBS for this indication.

OBJECTIVE

To provide the first estimates of the likely cost-effectiveness of DBS in the treatment of severe TS.

METHODS

We conducted a cost-utility analysis using clinical data from 17 Australian patients receiving DBS. Direct medical costs for DBS using non-rechargeable and rechargeable batteries and for the alternative best medical treatment (BMT), and health utilities for BMT were sourced from the literature. Incremental cost-effectiveness ratios (ICERs) were estimated using a Markov models with a 10-year time horizon and 5% discount rate.

RESULTS

DBS increased quality-adjusted life year (QALY) gained from 2.76 to 4.60 over a 10-year time horizon. The ICER for DBS with non-rechargeable (rechargeable) batteries, compared to BMT, was A$33,838 (A$15,859) per QALY. The ICER estimates are sensitive to DBS costs and selected time horizon.

CONCLUSIONS

Our study indicates that DBS may be a cost-effective treatment for severe TS, based on the very limited clinical data available and under particular assumptions. While the limited availability of data presents a challenge, we also conduct sensitivity analyses to test the robustness of the results to the assumptions used in the analysis. We nevertheless recommend the implementation of randomised controlled trials that collect a comprehensive range of costs and the use of a widely accepted health-related quality of life instrument to enable more definitive statements about the cost-effectiveness of DBS for TS.

A circuit view of deep brain stimulation in Alzheimer's disease and the possible mechanisms

Alzheimer's disease (AD) is characterized by chronic progressive cognitive deterioration frequently accompanied by psychopathological symptoms, including changes in personality and social isolation, which severely reduce quality of life. Currently, no viable therapies or present-day drugs developed for the treatment of AD symptoms are able to slow or reverse AD progression or prevent the advance of neurodegeneration. As such, non-drug alternatives are currently being tested, including deep brain stimulation (DBS). DBS is an established therapy for several neurological and psychiatric indications, such as movement disorders. Studies assessing DBS for other disorders have also found improvements in cognitive function, providing the impetus for clinical trials on DBS for AD. Targets of DBS in AD clinical trials and animal model studies include the fornix, entorhinal cortex (EC), nucleus basalis of Meynert (NBM), and vertical limb of diagonal band (VDB). However, there is still no comprehensive theory explaining the effects of DBS on AD symptoms or a consensus on which targets provide optimal benefits. This article reviews the anatomy of memory circuits related to AD, as well as studies on DBS rescue of AD in these circuits and the possible therapeutic mechanisms.

Current and future directions of deep brain stimulation for neurological and psychiatric disorders

Deep brain stimulation (DBS) has evolved considerably over the past 4 decades. Although it has primarily been used to treat movement disorders such as Parkinson's disease, essential tremor, and dystonia, recently it has been approved to treat obsessive-compulsive disorder and epilepsy. Novel potential indications in both neurological and psychiatric disorders are undergoing active study. There have been significant advances in DBS technology, including preoperative and intraoperative imaging, surgical approaches and techniques, and device improvements. In addition to providing significant clinical benefits and improving quality of life, DBS has also increased the understanding of human electrophysiology and network interactions. Despite the value of DBS, future developments should be aimed at developing less invasive techniques and attaining not just symptom improvement but curative disease modification.

Clinical Efficacy of Bilateral Deep Brain Stimulation Does Not Change After Implantable Pulse Generator Replacement but the Impedances Do: A Prospective Study

BACKGROUND

Deep brain stimulation (DBS) is an approved therapy option for movement disorders such as Parkinson's disease (PD), essential Tremor (ET), and dystonia. While current research focuses on rechargeable implantable pulse generators (IPGs), little is known about changes of the motor functions after IPG replacement and the consequences of additionally implanted hardware.

OBJECTIVE

To assess changes of the motor functions, the therapy impedances, and the total electric energy delivered (TEED) after elective IPG replacement.

METHODS

We prospectively acquired the data of 47 patients with PD, ET, and dystonia treated with bilateral DBS. Motor functions were rated prior to and after surgery using the revised Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS-III), the Fahn-Tolosa-Marin Tremor-Rating-Scale (FTM-TRS), and the Unified Dystonia Rating Scale (UDRS). Furthermore, the therapy impedances and TEED were assessed at the aforementioned times.

RESULTS

While preoperative motor scores were 48.32 ± 17.16 in PD, 39.71 ± 12.28 in ET, and 18.48 ± 16.30 in dystonia patients, postoperative scores were 47.84 ± 24.33, 32.86 ± 15.82, and 15.02 ± 15.17, respectively. Only in dystonia patients, motor scores significantly differed. Perioperative therapy impedance changes were 142.66 ± 105.35 Ω (Kinetra® to Activa® PC), -68.75 ± 43.05 Ω (Activa® PC to Activa® PC), and - 51.38 ± 38.75 Ω (Activa® PC to Activa® RC). Perioperative TEED changes were - 37.15 ± 38.87 μJ, 2.03 ± 35.91 μJ, and 12.39 ± 6.31 μJ in that first, second, and third group, respectively. Both the therapy impedances and TEED significantly differed between groups.

CONCLUSION

Although there were no statistically significant changes in the motor functions of all patients after elective IPG replacement, the therapy impedances were significantly higher and TEED was significantly lower after IPG replacement with concurrent Pocket Adapter implantation.

Cost-Effectiveness of Deep Brain Stimulation With Movement Disorders: A Systematic Review

BACKGROUND

Movement disorders (MDs) are increasingly being managed with deep brain stimulation (DBS). High-quality economic evaluations (EEs) are necessary to evaluate the cost-effectiveness of DBS. We conducted a systematic review of published EEs of the treatment of MDs with DBS. The review compares and contrasts the reported incremental cost-effectiveness ratios (ICERs) and methodology employed by trial-based evaluations (TBEs) and model-based evaluations (MBEs).

METHODS

MeSH and search terms relevant to "MDs," "DBS," and "EEs" were used to search biomedical and economics databases. Studies that used a comparative design to evaluate DBS, including before-after studies, were included. Quality and reporting assessments were conducted independently by 2 authors. Seventeen studies that targeted Parkinson's disease (PD), dystonia, and essential tremor (ET), met our selection criteria.

RESULTS

Mean scores for methodological and reporting quality were 73% and 76%, respectively. The ICERs for DBS compared with best medical therapy to treat PD patients obtained from MBEs had a lower mean and range compared with those obtained from TBEs ($55,461-$735,192 per quality-adjusted life-year [QALY] vs. $9,301-$65,111 per QALY). Pre-post ICER for DBS to treat dystonia was $64,742 per QALY. DBS was not cost-effective in treating ET compared with focused-ultrasound surgery. Cost-effectiveness outcomes were sensitive to assumptions in health utilities, surgical costs, battery life-span, model time horizons, and the discount rate.

CONCLUSIONS

The infrequent use of randomized, controlled trials to evaluate DBS efficacy, the paucity of data reporting the long-term effectiveness and/or utility of DBS, and the uncertainty surrounding cost data limit our ability to report cost-effectiveness summaries that are robust.