Alternative Deep Brain Stimulation Targets in the Treatment of Isolated Dystonic Syndromes: A Multicenter Experience-Based Survey

BACKGROUND

The globus pallidus internus (GPi) is the traditional evidence-based deep brain stimulation (DBS) target for treating dystonia. Although patients with isolated "primary" dystonia respond best to GPi-DBS, some are primary or secondary nonresponders (improvement <25%), showing variability in clinical response.

OBJECTIVE

The aim was to survey current practices regarding alternative DBS targets for isolated dystonia patients with focus on nonresponders to GPi-DBS.

METHODS

A 42-question survey was emailed and distributed during a DBS conference to clinicians involved in DBS for dystonia. The survey covered (1) use of alternative DBS targets as primary or rescue options, (2) target selection based on dystonia phenomenology, (3) experience with secondary nonresponders to GPi-DBS, and (4) management of patients with additional DBS leads.

RESULTS

The response rate was 53.8%, including neurologists and neurosurgeons from 28 DBS centers in 13 countries; 89% of neurologists and 86% of neurosurgeons used alternative DBS targets to GPi, with subthalamic nucleus being the most common initial or rescue alternative to GPi. Patients with additional tremor received DBS in the ventral intermediate nucleus or caudal zona incerta. Individual experience ranged from 5 to 25 patients. Most patients were still receiving dual target stimulation at the last follow-up.

CONCLUSIONS

We show that more than 85% of surveyed clinicians use alternative DBS targets, mostly in some isolated dystonia patients not adequately responsive to GPi-DBS. More knowledge is needed to evaluate outcomes in alternative targets and establish the best strategies for managing insufficient GPi-DBS response in dystonia patients with diverse phenomenology. Our article contributes to establishing a clearer time frame and criteria for defining nonresponders in dystonia patients undergoing DBS.

How Long Does Deep Brain Stimulation Give Patients Benefit?

INTRODUCTION

One of the most common questions patients ask when they are contemplating deep brain stimulation (DBS) is how long it will last. To guide physicians in answering this query, we performed a scoping review to assess the current state of the literature and to identify the gaps that need to be addressed.

MATERIALS AND METHODS

The authors performed a MEDLINE search inclusive of articles from January 1987 (advent of DBS literature) to June 2023 including human and modeling studies written in English. For longevity of therapy data, only studies with a mean follow-up of ≥three years were included. Using the Rayyan platform, two reviewers (JP and RM) performed a title screen. Of the 734 articles, 205 were selected by title screen and 109 from abstract review. Ultimately, a total of 122 articles were reviewed. The research questions we explored were 1) how long can the different components of the DBS system maintain functionality? and 2) how long can DBS remain efficacious in treating Parkinson's disease (PD), essential tremor (ET), dystonia, and other disorders?

RESULTS

We showed that patients with PD, ET, and dystonia maintain a considerable long-term benefit in motor scores seven to ten years after implant, although the percentage improvement decreases over time. Stimulation off scores in PD and ET show worsening, consistent with disease progression. Battery life varies by the disease treated and the programming settings used. There remains a paucity of literature after ten years, and the impact of new device technology has not been classified to date.

CONCLUSION

We reviewed existing data on DBS longevity. Overall, outcomes data after ten years of therapy are substantially limited in the current literature. We recommend that physicians who have data for patients with DBS exceeding this duration publish their results.

Long-Term Outcomes on Pallidal Neurostimulation for Dystonia: A Controlled, Prospective 10-Year Follow-Up

BACKGROUND

Pallidal neurostimulation is an effective treatment for severe isolated dystonia, but long-term data from clinical trials are lacking.

OBJECTIVES

To evaluate long-term efficacy and safety of pallidal neurostimulation in patients with isolated generalized or segmental dystonia.

METHODS

Extension study of the prospective multicenter trial (n = 40; July 2002 to May 2004), all patients received effective stimulation and underwent regular follow-up. The 10-year follow-up (n = 31) included Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor and disability score, Beck Depression Inventory, Beck Anxiety Inventory, and Mattis Dementia Rating Scale. Primary and secondary endpoints compared motor symptoms, disability scores, mood, and cognition changes.

RESULTS

Thirty-one patients (12 female), aged 23-72 years, completed the 10-year study extension. Per protocol analysis showed sustained significant improvement in BFMDRS motor scores at 10 years compared with baseline, without significant change from the 6-month or 5-year follow-up. On average, motor scores decreased by 25.3 ± 5.2 points at 10 years (P < 0.0001; 56% improvement). Individual outcomes varied, with 27 responders (≥25% improvement; mean improvement 65.2 ± 21.4%) and 13 non-responders compared with baseline. Sustained improvements were seen in disability, mood, and anxiety scores. Cognition remained stable.

CONCLUSIONS

This study presents the longest prospective, multicenter follow-up of pallidal neurostimulation in generalized and segmental dystonia. Two-thirds of patients showed strong and stable long-term improvements of dystonia, confirming sustained efficacy and safety over 10 years in treatment-refractory dystonic patients. However, one-third experienced primary (3/40) or secondary (10/40) treatment failure. Diagnostic advances, including genetic testing, and technological progress in pallidal neurostimulation may help to reduce the non-responder rates in the future. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Emerging therapies for childhood-onset movement disorders

PURPOSE OF REVIEW

We highlight novel and emerging therapies in the treatment of childhood-onset movement disorders. We structured this review by therapeutic entity (small molecule drugs, RNA-targeted therapeutics, gene replacement therapy, and neuromodulation), recognizing that there are two main approaches to treatment: symptomatic (based on phenomenology) and molecular mechanism-based therapy or 'precision medicine' (which is disease-modifying).

RECENT FINDINGS

We highlight reports of new small molecule drugs for Tourette syndrome, Friedreich's ataxia and Rett syndrome. We also discuss developments in gene therapy for aromatic l-amino acid decarboxylase deficiency and hereditary spastic paraplegia, as well as current work exploring optimization of deep brain stimulation and lesioning with focused ultrasound.

SUMMARY

Childhood-onset movement disorders have traditionally been treated symptomatically based on phenomenology, but focus has recently shifted toward targeted molecular mechanism-based therapeutics. The development of precision therapies is driven by increasing capabilities for genetic testing and a better delineation of the underlying disease mechanisms. We highlight novel and exciting approaches to the treatment of genetic childhood-onset movement disorders while also discussing general challenges in therapy development for rare diseases. We provide a framework for molecular mechanism-based treatment approaches, a summary of specific treatments for various movement disorders, and a clinical trial readiness framework.

The role of genetics in the treatment of dystonia with deep brain stimulation: Systematic review and Meta-analysis

BACKGROUND

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions that lead to involuntary postures or repetitive movements. Genetic mutations are being increasingly recognized as a cause of dystonia. Deep brain stimulation (DBS) is one of the limited treatment options available. However, there are varying reports on its efficacy in genetic dystonias. This systematic review of the characteristics of genetic dystonias treated with DBS and their outcomes aims to aid in the evaluation of eligibility for such treatment.

METHODS

We performed a PUBMED search of all papers related to genetic dystonias and DBS up until April 2022. In addition to performing a systematic review, we also performed a meta-analysis to assess the role of the mutation on DBS response. We included cases that had a confirmed genetic mutation and DBS along with pre-and post-operative BFMDRS.

RESULTS

Ninety-one reports met our inclusion criteria and from them, 235 cases were analyzed. Based on our analysis DYT-TOR1A dystonia had the best evidence for DBS response and Rapid-Onset Dystonia Parkinsonism was among the least responsive to DBS.

CONCLUSION

While our report supports the role of genetics in DBS selection and response, it is limited by the rarity of the individual genetic conditions, the reliance on case reports and case series, and the limited ability to obtain genetic testing on a large scale in real-time as opposed to retrospectively as in many cases.

Applicability of clinical genetic testing for deep brain stimulation treatment in monogenic Parkinson's disease and monogenic dystonia: a multidisciplinary team perspective

In this perspective article, we highlight the possible applicability of genetic testing in Parkinson's disease and dystonia patients treated with deep brain stimulation (DBS). DBS, a neuromodulatory technique employing electrical stimulation, has historically targeted motor symptoms in advanced PD and dystonia, yet its precise mechanisms remain elusive. Genetic insights have emerged as potential determinants of DBS efficacy. Known PD genes such as GBA, SNCA, LRRK2, and PRKN are most studied, even though further studies are required to make firm conclusions. Variable outcomes depending on genotype is present in genetic dystonia, as DYT-TOR1A, NBIA/DYTPANK2, DYT-SCGE and X-linked dystonia-parkinsonism have demonstrated promising outcomes following GPi-DBS, while varying outcomes have been documented in DYT-THAP1. We present two clinical vignettes that illustrate the applicability of genetics in clinical practice, with one PD patient with compound GBA mutations and one GNAL dystonia patient. Integrating genetic testing into clinical practice is pivotal, particularly with advancements in next-generation sequencing. However, there is a clear need for further research, especially in rarer monogenic forms. Our perspective is that applying genetics in PD and dystonia is possible today, and despite challenges, it has the potential to refine patient selection and enhance treatment outcomes.

Deep brain stimulation effect in genetic dyskinetic cerebral palsy: The case of ADCY5- related disease

BACKGROUND

Cerebral Palsy (CP) represents a frequent cause of disability in childhood. Early in life, genetic disorders may present with motor dysfunction and diagnosed as CP. Establishing the primary, genetic etiology allows more accurate prognosis, genetic counselling, and planning for symptomatic interventions in homogeneous etiological groups. Deep brain stimulation (DBS) is recommended in refractory movement disorders, including isolated pediatric dystonias. For dystonia evolving in more complex associations in genetic CP, the effect of DBS is still understudied and currently only sporadically described.

OBJECTIVES

To report the effect of DBS applied to the globus pallidus pars interna (GPi) in children with complex movement disorders caused by pathogenic ADCY5 variants, diagnosed as dyskinetic CP previous to genetic diagnostic.

METHODS

We conducted a retrospective study on evolution of treatment with DBS in ADCY5-related disease. A standardized proforma including the different type of movement disorders and associated neurological signs was completed at each follow-up time, based on video recordings, as well as functional assessments used in children with CP.

RESULTS

Four children (mean of age, 13 ± 2.9 years) received GPi-DBS. The same de novo pathogenic missense variant (c.1252C > T, p.R418W) was identified in three out of four and a splice site variant (c.2088 + 2G > T) in one subject. Developmental delay and overlapping features including axial hypotonia, chorea, dystonic attacks, myoclonus, and cranial dyskinesia were present. The median age at DBS was 9 years and follow-up with DBS, 2.6 years. We identified a pattern of clinical response with early suppression of dystonic attacks, followed by improvement of myoclonus and facial dyskinesia. Effect on chorea was delayed and more limited. Two patients gained notable functional benefit related to sitting, standing, gait, use of upper limbs and speech.

CONCLUSION

ADCY5-related disease may benefit from GPi-DBS. The most significant clinical response relates to the early and sustained benefit on dystonic attacks and a variable but still positive response on the other hyperkinetic features. Genetic etiology of CP will contribute to further elucidate genotype-phenotype correlations and to refine DBS indication as network-related symptomatic interventions.

Deep brain stimulation in dystonia: factors contributing to variability in outcome in short and long term follow-up

PURPOSE OF REVIEW

Deep brain stimulation (DBS) is currently the most effective treatment for medically refractory dystonia with globus pallidus internus (GPi) usually the preferred target. Despite the overall success of DBS in dystonia, there remains variability in treatment outcome in both short and long-term follow-up, due to various factors. Factors contributing to variability in outcome comprise 'Dystonia Related' including dystonia classification, semiology, duration, body distribution, orthopaedic deformity, aetiology and genetic cause. The majority of these factors are identifiable from clinical assessment, brain MRI and genetic testing, and therefore merit careful preoperative consideration. 'DBS related' factors include brain target, accuracy of lead placement, stimulation parameters, time allowed for response, neurostimulation technology employed and DBS induced side-effects. In this review, factors contributing to variability in short and long-term dystonia DBS outcome are reviewed and discussed.

RECENT FINDINGS

The recognition of differential DBS benefit in monogenic dystonia, increasing experience with subthalamic nucleus (STN) DBS and in DBS for Meige syndrome, elucidation of DBS side effects and novel neurophysiological and imaging techniques to assist in predicting clinical outcome.

SUMMARY

Improved understanding of factors contributing to variability of DBS outcome in dystonia may assist in patient selection and predicting surgical outcomes.

Surgical Outcomes in Rare Movement Disorders: A Report of Seventeen Patients from India and Review of Literature

Background:

Rare movement disorders (RMDs) throw remarkable challenges to their appropriate management particularly when they are medically refractory. We studied the outcome of functional neurosurgery among patients with RMDs.

Methods:

Retrospective chart-review from 2006 to 2021 of patients with RMDs who underwent either Deep brain Stimulation (DBS) or lesional surgeries in the department of Neurology and Neurosurgery at a tertiary care centre.

Results:

Seventeen patients were included. Generalized dystonia (11 patients, 64.7%) and tremor (5 patients, 29.4%) were the most common indication for surgery whereas, Wilson’s disease (8 patients, 47.1%) and Neurodegeneration with brain iron accumulation (5 patients, 29.4%) were the most common aetiology. Sixteen patients (94.1%) had objective clinical improvement. Significant improvement was noted in the dystonia motor scores both at 6-months and 12-months follow-up (n = 11, p-value of <0.01 and 0.01 respectively). Comparison between DBS and lesional surgery showed no significant difference in the outcomes (p = 0.95 at 6-months and p = 0.53 at 12-months), with slight worsening of scores in the DBS arm at 12-months. Among five patients of refractory tremor with Wilson’s disease, there was remarkable improvement in the tremor scores by 85.0 ± 7.8% at the last follow-up. Speech impairment was the main complication observed with most of the other adverse events either transient or reversible.

Discussion:

Surgical options should be contemplated among patients with disabling medically refractory RMDs irrespective of the aetiology. Key to success lies in appropriate patient selection. In situations when DBS is not feasible, lesional surgeries can offer an excellent alternative with comparable efficacy and safety.

Deep Brain Stimulation Treating Dystonia: A Systematic Review of Targets, Body Distributions and Etiology Classifications

Background: Deep brain stimulation (DBS) is a typical intervention treating drug-refractory dystonia. Currently, the selection of the better target, the GPi or STN, is debatable. The outcomes of DBS treating dystonia classified by body distribution and etiology is also a popular question.

Objective: To comprehensively compare the efficacy, quality of life, mood, and adverse effects (AEs) of GPi-DBS vs. STN-DBS in dystonia as well as in specific types of dystonia classified by body distribution and etiology.

Methods: PubMed, Embase, the Cochrane Library, and Google Scholar were searched to identify studies of GPi-DBS and STN-DBS in populations with dystonia. The efficacy, quality of life, mood, and adverse effects were quantitatively compared. Meta-regression analyses were also performed. This analysis has been registered in PROSPERO under the number CRD42020146145.

Results: Thirty five studies were included in the main analysis, in which 319 patients underwent GPI-DBS and 113 patients underwent STN-DBS. The average follow-up duration was 12.48 months (range, 3–49 months). The GPI and STN groups were equivalent in terms of efficacy, quality of life, mood, and occurrence of AEs. The focal group demonstrated significantly better disability symptom improvement (P = 0.012) than the segmental and generalized groups but showed less SF-36 enhancement than the segmental group (P < 0.001). The primary groups exhibited significantly better movement and disability symptom improvements than the secondary non-hereditary group (P < 0.005), which demonstrated only disability symptom improvement compared with the secondary hereditary group (P < 0.005). The primary hereditary and idiopathic groups had a significantly lower frequency of AEs than the secondary non-hereditary group (P < 0.005). The correlation between disability symptom improvement and movement symptom improvement was also significant (P < 0.05).

Conclusion: GPi-DBS and STN-DBS were both safe and resulted in excellent improvement in efficacy and quality of life in patients with dystonia. Compared with patients with segmental dystonia, patients with focal dystonia demonstrated better improvement in dystonia symptoms but less enhancement of quality of life. Those with primary dystonia had a better response to DBS in terms of efficacy than those with secondary dystonia. Patients who exhibit a significant improvement in movement symptoms might also exhibit excellent improvement in disability symptoms.

Habituation After Deep Brain Stimulation in Tremor Syndromes: Prevalence, Risk Factors and Long-Term Outcomes

Deep brain stimulation (DBS) of the thalamus is an effective treatment for medically refractory essential, dystonic and Parkinson's tremor. It may also provide benefit in less common tremor syndromes including, post-traumatic, cerebellar, Holmes, neuropathic and orthostatic tremor. The long-term benefit of DBS in essential and dystonic tremor (ET/DT) often wanes over time, a phenomena referred to as stimulation "tolerance" or "habituation". While habituation is generally accepted to exist, it remains controversial. Attempts to quantify habituation have revealed conflicting reports. Placebo effects, loss of micro-lesional effect, disease related progression, suboptimal stimulation and stimulation related side-effects may all contribute to the loss of sustained long-term therapeutic effect. Habituation often presents as substantial loss of initial DBS benefit occurring as early as a few months after initial stimulation; a complex and feared issue when faced in the setting of optimal electrode placement. Simply increasing stimulation current tends only to propagate tremor severity and induce stimulation related side effects. The report by Paschen and colleagues of worsening tremor scores in the "On" vs. "Off" stimulation state over time, even after accounting for "rebound" tremor, supports the concept of habituation. However, these findings have not been consistent across all studies. Chronic high intensity stimulation has been hypothesized to induce detrimental plastic effects on tremor networks, with some lines of evidence that DT and ET may be more susceptible than Parkinson's tremor to habituation. However, Tsuboi and colleague's recent longitudinal follow-up in dystonic and "pure" essential tremor suggests otherwise. Alternatively, post-mortem findings support a biological adaption to stimulation. The prevalence and etiology of habituation is still not fully understood and management remains difficult. A recent study reported that alternating thalamic stimulation parameters at weekly intervals provided improved stability of tremor control consistent with reduced habituation. In this article the available evidence for habituation after DBS for tremor syndromes is reviewed; including its prevalence, time-course, possible mechanisms; along with expected long-term outcomes for tremor and factors that may assist in predicting, preventing and managing habituation.

Deep Brain Stimulation for Pediatric Dystonia

Dystonia is one of the most common pediatric movement disorders and can have a profound impact on the lives of children and their caregivers. Response to pharmacologic treatment is often unsatisfactory. Deep brain stimulation (DBS) has emerged as a promising treatment option for children with medically refractory dystonia. In this review we highlight the relevant literature related to DBS for pediatric dystonia, with emphasis on the background, indications, prognostic factors, challenges, and future directions of pediatric DBS.

Globus Pallidus Internus Deep Brain Stimulation Using Frame-Based vs. Frameless Stereotaxy in Dystonia: A Single-Center Experience

Objective: Bilateral globus pallidus internus deep brain stimulation (GPi-DBS) is an established and effective therapy for primary refractory dystonia. However, the comparison of frameless vs. frame-based DBS surgery technique is still controversial. This retrospective study aims to compare the clinical outcome of two GPi-DBS surgical techniques for patients affected by primary generalized or multi-segmental dystonia.

Methods: For lead's stereotaxic placement, 10 patients underwent frame-based surgery and the other 10 subjects DBS surgery with a frameless technique. Clinical features were evaluated at baseline and 6 and 12 months after surgery by means of the Burke–Fahn–Marsden Dystonia Rating Scale.

Results: Frame-based GPi-DBS and frameless stereotaxic group revealed a comparable clinical outcome with no surgical complications.

Conclusions: Frameless technique is safe and well-tolerated by patients and showed similar effectiveness of the frame-based stereotaxic surgery during GPi-DBS for primary dystonia. Notably, it could be a valid alternative solution because of the great advantage in improving the patient's discomfort during awake surgery.

A practical guide to troubleshooting pallidal deep brain stimulation issues in patients with dystonia

High frequency deep brain stimulation (DBS) of the internal portion of the globus pallidus has, in the last two decades, become a mainstream therapy for the management of medically-refractory dystonia syndromes. Such increasing uptake places an onus on movement disorder physicians to become familiar with this treatment modality, in particular optimal patient selection for the procedure and how to troubleshoot problems relating to sub-optimal efficacy and therapy-related side effects. Deep brain stimulation for dystonic conditions presents some unique challenges. For example, the frequent lack of immediate change in clinical status following stimulation alterations means that programming often relies on personal experience and local practice rather than real-time indicators of efficacy. Further, dystonia is a highly heterogeneous disorder, making the development of unifying guidelines and programming algorithms for DBS in this population difficult. Consequently, physicians may feel less confident in managing DBS for dystonia as compared to other indications e.g. Parkinson's disease. In this review, we integrate our years of personal experience of the programming of DBS systems for dystonia with a critical appraisal of the literature to produce a practical guide for troubleshooting common issues encountered in patients with dystonia treated with DBS, in the hope of improving the care for these patients.

Efficacy and safety of general anesthesia deep brain stimulation for dystonia: an individual patient data meta-analysis of 341 cases

OBJECTIVE

The efficacy and safety of deep brain stimulation (DBS) under general anesthesia for the treatment of dystonia have not yet been confirmed with high level of evidence. This meta-analysis with pooled individual patient data aims to assess the clinical outcomes and identify the potential prognostic factors of dystonia patients who underwent general anesthesia DBS.

METHODS

We searched PubMed, Web of Science, and Embase for articles describing patients with dystonia who underwent asleep DBS and had individual Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores. The relative improvement in BFMDRS scores was considered the primary outcome. Pearson correlation analyses and multivariate linear regression analysis were conducted to explore the prognostic factors.

RESULTS

A total of 34 studies involving 341 patients were included. The mean postoperative improvement in BFMDRS-M (BFMDRS movement subscale) and BFMDRS-D (BFMDRS disability subscale) scores were 58.6±36.2% and 48.5±38.7% at the last follow-up visit, respectively, with a mean follow-up time of 22.4±27.6 months. Age at surgery and disease duration showed a negative correlation with the percent improvement of BFMDRS-M (%) at the last visit (r=-0.134, P=0.013; r=-0.165, P=0.006). In the stepwise multivariate regression, only disease duration remained a relevant factor. Additionally, the adverse events were acceptable.

CONCLUSION

General anesthesia DBS is a safe, effective, and feasible option for dystonia patients in the long term. Shorter disease duration predicts better clinical outcomes.

Arching deep brain stimulation in dystonia types

Although medical treatment including botulinum toxic injection is the first-line treatment for dystonia, response is insufficient in many patients. In these patients, deep brain stimulation (DBS) can provide significant clinical improvement. Mounting evidence indicates that DBS is an effective and safe treatment for dystonia, especially for idiopathic and inherited isolated generalized/segmental dystonia, including DYT-TOR1A. Other inherited dystonia and acquired dystonia also respond to DBS to varying degrees. For Meige syndrome (craniofacial dystonia), other focal dystonia, and some rare inherited dystonia, further evidences are still needed to evaluate the role of DBS. Because short disease duration at DBS surgery and absence of fixed musculoskeletal deformity are associated with better outcome, DBS should be considered as early as possible when indicated after careful evaluation including genetic work-up. This review will focus on the factors to be considered in DBS for patients with dystonia and the outcome of DBS in the different types of dystonia.

[Deep brain stimulation in neurological and psychiatric diseases]

Die invasive Hirnstimulation (tiefe Hirnstimulation [THS], „deep brain stimulation“ [DBS]) ist mittlerweile ein etabliertes Therapieverfahren bei einer Reihe neurologischer Erkrankungen insbesondere Bewegungsstörungen. Die Anzahl der mit einer THS versorgten Patienten steigt stetig, die technische Entwicklung der THS-Systeme schreitet voran und neue Indikationen werden aktuell in Studien überprüft. Im folgenden Beitrag soll ein Überblick über die aktuellen Indikationen und ein Ausblick auf zukünftige Entwicklungen der THS bei Bewegungsstörungen und psychiatrischen Erkrankungen gegeben werden.

Long-term effects of pallidal and thalamic deep brain stimulation in myoclonus dystonia

OBJECTIVE

Observational study to evaluate long-term effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the ventral intermediate thalamic nucleus (VIM) on patients with medically refractory myoclonus dystonia (MD).

BACKGROUND

More recently, pallidal as well as thalamic DBS have been applied successfully in MD but long-term data are sparse.

METHODS

We retrospectively analyzed a cohort of seven MD patients with either separate (n = 1, VIM) or combined GPi- DBS and VIM-DBS (n = 6). Myoclonus, dystonia and disability were rated at baseline (BL), short-term (ST-FU) and long-term follow-up (LT-FU) using the United Myoclonus Rating Scale, Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Tsui rating scale, respectively. Quality of life (QoL) and mood were evaluated using the SF-36 and Beck Depression Inventory questionnaires, respectively.

RESULTS

Patients reached a significant reduction of myoclonus at ST-FU (62% ± 7.3%; mean ± SE) and LT-FU (68% ± 3.4%). While overall motor BFMDRS changes were not significant at LT-FU, patients with GPi-DBS alone responded better and predominant cervical dystonia ameliorated significantly up to 54% ± 9.7% at long-term. Mean disability scores significantly improved by 44% ± 11.4% at ST-FU and 58% ± 14.8% at LT-FU. Mood and QoL remained unchanged between 5 and up to 20 years postoperatively. No serious long-lasting stimulation-related adverse events were observed.

CONCLUSIONS

We present a cohort of MD patients with very long follow-up of pallidal and/or thalamic DBS that supports the GPi as the favourable stimulation target in MD with safe and sustaining effects on motor symptoms (myoclonus>dystonia) and disability.

Deep Brain Stimulation Initiative: Toward Innovative Technology, New Disease Indications, and Approaches to Current and Future Clinical Challenges in Neuromodulation Therapy

Deep brain stimulation (DBS) is one of the most important clinical therapies for neurological disorders. DBS also has great potential to become a great tool for clinical neuroscience research. Recently, the National Engineering Laboratory for Neuromodulation at Tsinghua University held an international Deep Brain Stimulation Initiative workshop to discuss the cutting-edge technological achievements and clinical applications of DBS. We specifically addressed new clinical approaches and challenges in DBS for movement disorders (Parkinson's disease and dystonia), clinical application toward neurorehabilitation for stroke, and the progress and challenges toward DBS for neuropsychiatric disorders. This review highlighted key developments in (1) neuroimaging, with advancements in 3-Tesla magnetic resonance imaging DBS compatibility for exploration of brain network mechanisms; (2) novel DBS recording capabilities for uncovering disease pathophysiology; and (3) overcoming global healthcare burdens with online-based DBS programming technology for connecting patient communities. The successful event marks a milestone for global collaborative opportunities in clinical development of neuromodulation to treat major neurological disorders.

Pallidal Deep Brain Stimulation for Monogenic Dystonia: The Effect of Gene on Outcome

Globus pallidus internus deep brain stimulation (GPi DBS) is the most effective intervention for medically refractory segmental and generalized dystonia in both children and adults. Predictive factors for the degree of improvement after GPi DBS include shorter disease duration and dystonia subtype with idiopathic isolated dystonia usually responding better than acquired combined dystonias. Other factors contributing to variability in outcome may include body distribution, pattern of dystonia and DBS related factors such as lead placement and stimulation parameters. The responsiveness to DBS appears to vary between different monogenic forms of dystonia, with some improving more than others. The first observation in this regard was reports of superior DBS outcomes in DYT-TOR1A (DYT1) dystonia, although other studies have found no difference. Recently a subgroup with young onset DYT-TOR1A, more rapid progression and secondary worsening after effective GPi DBS, has been described. Myoclonus dystonia due to DYT-SCGE (DYT11) usually responds well to GPi DBS. Good outcomes following GPi DBS have also been documented in X-linked dystonia Parkinsonism (DYT3). In contrast, poorer, more variable DBS outcomes have been reported in DYT-THAP1 (DYT6) including a recent larger series. The outcome of GPi DBS in other monogenic isolated and combined dystonias including DYT-GNAL (DYT25), DYT-KMT2B (DYT28), DYT-ATP1A3 (DYT12), and DYT-ANO3 (DYT24) have been reported with varying results in smaller numbers of patients. In this article the available evidence for long term GPi DBS outcome between different genetic dystonias is reviewed to reappraise popular perceptions of expected outcomes and revisit whether genetic diagnosis may assist in predicting DBS outcome.

Deep brain stimulation treatment in dystonia: a bibliometric analysis

BACKGROUND

Dystonia is a heterogeneous disorder that, when refractory to medical treatment, may have a favorable response to deep brain stimulation (DBS). A practical way to have an overview of a research domain is through a bibliometric analysis, as it makes it more accessible for researchers and others outside the field to have an idea of its directions and needs.

OBJECTIVE

To analyze the 100 most cited articles in the use of DBS for dystonia treatment in the last 30 years.

METHODS

The research protocol was performed in June 2019 in Elsevier's Scopus database, by retrieving the most cited articles regarding DBS in dystonia. We analyzed authors, year of publication, country, affiliation, and targets of DBS.

RESULTS

Articles are mainly published in Movement Disorders (19%), Journal of Neurosurgery (9%), and Neurology (9%). European countries offer significant contributions (57% of our sample). France (192.5 citations/paper) and Germany (144.1 citations/paper) have the highest citation rates of all countries. The United States contributes with 31% of the articles, with 129.8 citations/paper. The publications are focused on General outcomes (46%), followed by Long-term outcomes (12.5%), and Complications (11%), and the leading type of dystonia researched is idiopathic or inherited, isolated, segmental or generalized dystonia, with 27% of articles and 204.3 citations/paper.

CONCLUSIONS

DBS in dystonia research is mainly published in a handful of scientific journals and focused on the outcomes of the surgery in idiopathic or inherited, isolated, segmental or generalized dystonia, and with globus pallidus internus as the main DBS target.

Asleep Deep Brain Stimulation in Patients With Isolated Dystonia: Stereotactic Accuracy, Efficacy, and Safety

OBJECTIVES

Lead placement for deep brain stimulation (DBS) is routinely performed using neuroimaging or microelectrode recording (MER). Recent studies have demonstrated that DBS under general anesthesia using an imaging-guided target technique ("asleep" DBS) can be performed accurately and effectively with lower surgery complication rates than the MER-guided target method under local anesthesia ("awake" DBS). This suggests that asleep DBS may be a more acceptable method. However, there is limited direct evidence focused on isolated dystonia using this method. Therefore, this study aimed to investigate the clinical outcomes and targeting accuracy in patients with dystonia who underwent asleep DBS.

MATERIALS AND METHODS

We examined 56 patients (112 leads) with isolated dystonia who underwent asleep DBS targeting in the globus pallidus internus (GPi) and subthalamic nucleus (STN). The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores were assessed preoperatively and at 12-month follow-up (12 m-FU). The lead accuracy was evaluated by comparing the coordinates of the preoperative plan with those of the final electrode implantation location. Other measures analyzed included stimulation parameters and adverse events (AEs).

RESULTS

For both GPi and STN cohorts, mean BFMDRS motor scores were significantly lower at 12 m-FU (8.9 ± 10.9 and 4.6 ± 5.7 points) than at baseline (22.6 ± 16.4 and 16.1 ± 14.1 points, p < 0.001). The mean difference between the planned target and the distal contact of the leads was 1.33 ± 0.54 mm for the right brain electrodes and 1.50 ± 0.57 mm for the left, determined by Euclidian distance. No perioperative complications or AEs related to the device were observed during the complete follow-up. However, AEs associated with stimulation occurred in 12 and 6 patients in the GPi and STN groups, respectively.

CONCLUSIONS

Asleep DBS may be an accurate, effective, and safe method for treating patients with isolated dystonia regardless of the stimulation target.

KMT2B-related disorders: expansion of the phenotypic spectrum and long-term efficacy of deep brain stimulation

Heterozygous mutations in KMT2B are associated with an early-onset, progressive and often complex dystonia (DYT28). Key characteristics of typical disease include focal motor features at disease presentation, evolving through a caudocranial pattern into generalized dystonia, with prominent oromandibular, laryngeal and cervical involvement. Although KMT2B-related disease is emerging as one of the most common causes of early-onset genetic dystonia, much remains to be understood about the full spectrum of the disease. We describe a cohort of 53 patients with KMT2B mutations, with detailed delineation of their clinical phenotype and molecular genetic features. We report new disease presentations, including atypical patterns of dystonia evolution and a subgroup of patients with a non-dystonic neurodevelopmental phenotype. In addition to the previously reported systemic features, our study has identified co-morbidities, including the risk of status dystonicus, intrauterine growth retardation, and endocrinopathies. Analysis of this study cohort (n = 53) in tandem with published cases (n = 80) revealed that patients with chromosomal deletions and protein truncating variants had a significantly higher burden of systemic disease (with earlier onset of dystonia) than those with missense variants. Eighteen individuals had detailed longitudinal data available after insertion of deep brain stimulation for medically refractory dystonia. Median age at deep brain stimulation was 11.5 years (range: 4.5-37.0 years). Follow-up after deep brain stimulation ranged from 0.25 to 22 years. Significant improvement of motor function and disability (as assessed by the Burke Fahn Marsden's Dystonia Rating Scales, BFMDRS-M and BFMDRS-D) was evident at 6 months, 1 year and last follow-up (motor, P = 0.001, P = 0.004, and P = 0.012; disability, P = 0.009, P = 0.002 and P = 0.012). At 1 year post-deep brain stimulation, >50% of subjects showed BFMDRS-M and BFMDRS-D improvements of >30%. In the long-term deep brain stimulation cohort (deep brain stimulation inserted for >5 years, n = 8), improvement of >30% was maintained in 5/8 and 3/8 subjects for the BFMDRS-M and BFMDRS-D, respectively. The greatest BFMDRS-M improvements were observed for trunk (53.2%) and cervical (50.5%) dystonia, with less clinical impact on laryngeal dystonia. Improvements in gait dystonia decreased from 20.9% at 1 year to 16.2% at last assessment; no patient maintained a fully independent gait. Reduction of BFMDRS-D was maintained for swallowing (52.9%). Five patients developed mild parkinsonism following deep brain stimulation. KMT2B-related disease comprises an expanding continuum from infancy to adulthood, with early evidence of genotype-phenotype correlations. Except for laryngeal dysphonia, deep brain stimulation provides a significant improvement in quality of life and function with sustained clinical benefit depending on symptoms distribution.

Generalized Dystonia Treated With Deep Brain Stimulator: An Institutional Single Surgeon Experience

Introduction

Dystonia can cause severe disability when left untreated. Once a patient has exhausted medical management, surgical intervention may be the only treatment option. Although not curative, deep brain stimulation has been shown to be beneficial for patients affected by this condition. Our study sought to review patients undergoing deep brain stimulation for medically refractory dystonia to assess outcomes.

Methods

Our institution's operative database was reviewed retrospectively for all patients undergoing deep brain stimulator placement over the last six years. These medical records were reviewed for the severity of dystonia preoperatively and followed postoperatively for 24 months, focusing on the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Patients with less than two-year postoperative follow-up were excluded from the study. The patients were further stratified by age into Group A, consisting of patients less than 40 years old, and Group B, patients greater than or equal to 40 years old. Other attributes such as age, sex, age of disease onset, disease duration at the time of surgery, genetic tests for dystonia-related genes, and any complication associated with surgery were also reviewed.

Results

Four hundred fifty-five operative cases for deep brain stimulator placement were reviewed, and 16 patients met inclusion criteria for the study. The mean age for our patient cohort was 43.75 years, with four males and 12 females. The average time from the age of disease onset to time of surgery was 9.7 years for Group A and 10.8 years for Group B; the overall average was 10.3 years. All patients had globus pallidus interna (GPi) as their surgical target. The first incidence of a statistically significant decrease in BFMDRS score was noted at three months postoperatively (p<0.001) when compared to preoperative values. Fourteen patients in our cohort underwent preoperative genetic testing for DYT gene mutations, out of which four were found to have a mutation.

Conclusion

Our review of outcomes for primary generalized dystonia at our institution found that deep brain stimulator targeting the GPi is safe and effective. We found an overall 88% response rate with younger patients (< 40-year-old) showing a better response at two years than older patients.

Quality of life outcomes after globus pallidus internus deep brain stimulation in idiopathic or inherited isolated dystonia: a meta-analysis

BACKGROUND

Several studies reported the beneficial effects of globus pallidus internus deep brain stimulation (GPi DBS) on health-related quality of life (HRQoL) in patients with inherited or idiopathic isolated dystonia. However, the impact of this intervention on physical and mental/psychological domains and the effects over time remain unclear.

METHODS

We conducted a systematic literature review from January 2000 to May 2019 and performed a meta-analysis of HRQoL outcomes based on the Short Form Health Survey-36 (SF-36) after GPi DBS in patients with inherited or idiopathic isolated dystonia to evaluate the effects of DBS on physical and mental QoL.

RESULTS

Seven studies comprising 144 patients with dystonia (78, generalised; 34, segmental; and 32, focal cervical) were included in this comprehensive analysis. The mean (SD) age at DBS implantation was 41.0 (11.4) years, and the follow-up period after implantation was 3.2 (3.8) years. The random effects model meta-analysis revealed that both physical and mental domains of SF-36 improved following DBS with a significantly larger effect size for the physical domains (effect size=0.781; p<0.0001) compared with the mental domains (effect size=0.533; p<0.0001). A moderator variable analysis demonstrated that effect sizes for HRQoL improvement were maintained over time.

CONCLUSIONS

This is the first meta-analysis that demonstrates significant benefits in HRQoL following DBS in patients with inherited or idiopathic isolated dystonia. The benefits are greater for physical QoL domains compared with mental/psychological QoL. These findings highlight the importance of a comprehensive multidisciplinary approach to improve mental/psychological QoL.

Secondary Worsening Following DYT1 Dystonia Deep Brain Stimulation: A Multi-country Cohort

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as <30% improvement in dystonia scales at the last follow-up compared with baseline. We used a literature-driven historical cohort of 112 DYT1 patients for comparison. Results: Approximately 8% of our study cohort (11 out of 132) experienced suboptimal responses to DBS. Compared with the historical cohort, the multi-country cohort with suboptimal responses had a significantly younger age at onset (mean, 7.0 vs. 8.4 years; p = 0.025) and younger age at DBS (mean, 12.0 vs. 18.6 years; p = 0.019). Additionally, cranial involvement was more common in the multi-country cohort (before DBS, 64% vs. 45%, p = 0.074; before or after DBS, 91% vs. 47%, p = 0.001). Mean motor improvement at the last follow-up from baseline were 0% and 66% for the multi-country and historical cohorts, respectively. All 11 patients of the multi-country cohort had generalization of dystonia within 2.5 years after disease onset. All patients experienced dystonia improvement of >30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

Deep brain stimulation of the globus pallidus internus versus the subthalamic nucleus in isolated dystonia

OBJECTIVE

Surgical procedures involving deep brain stimulation (DBS) of the globus pallidus internus (GPi) or subthalamic nucleus (STN) are well-established treatments for isolated dystonia. However, selection of the best stimulation target remains a matter of debate. The authors' objective was to compare the effectiveness of DBS of the GPi and the STN in patients with isolated dystonia.

METHODS

In this matched retrospective cohort study, the authors searched an institutional database for data on all patients with isolated dystonia who had undergone bilateral implantation of DBS electrodes in either the GPi or STN in the period from January 30, 2014, to June 30, 2017. Standardized assessments of dystonia and health-related quality of life using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and SF-36 were conducted before and at 1, 6, and 12 months after surgery. No patients were lost to the 6-month follow-up; 5 patients were lost to the 12-month follow-up.

RESULTS

Both GPi (14 patients) and STN (16 patients) stimulation produced significant improvement in dystonia and quality of life in all 30 patients found in the database search. At the 1-month follow-up, however, the percentage improvement in the BFMDRS total movement score was significantly (p = 0.01) larger after STN DBS (64%) than after GPi DBS (48%). At the 12-month follow-up, the percentage improvement in the axis subscore was significantly (p = 0.03) larger after GPi DBS (93%) than after STN DBS (83%). Also, the total amount of electrical energy delivered was significantly (p = 0.008) lower with STN DBS than with GPi DBS (124 ± 52 vs 192 ± 65 μJ, respectively).

CONCLUSIONS

The GPi and STN are both effective targets in alleviating dystonia and improving quality of life. However, GPi stimulation may be better for patients with axial symptoms. Moreover, STN stimulation may produce a larger clinical response within 1 month after surgery and may have a potential economic advantage in terms of lower battery consumption.

Long-term effects of bilateral pallidal deep brain stimulation in dystonia: a follow-up between 8 and 16 years

Objective

Observational study to evaluate the long-term motor and non-motor effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) on medically refractory dystonia.

Background

Dystonia is a chronic disease affecting mainly young patients with a regular life expectancy and lifelong need for therapy. Pallidal DBS is an established treatment for severe isolated dystonia but long-term data are sparse.

Methods

We considered 36 consecutive patients with isolated generalized (n = 14) and cervical/segmental (n = 22) dystonia operated at Charité-University Hospital between 2000 and 2007 in a retrospective analysis for long-term outcome of pallidal DBS. In 19 of these patients, we could analyze dystonic symptoms and disability rated by the Burke–Fahn–Marsden Dystonia Rating scale (BFMDRS) at baseline, short-term (ST-FU, range 3–36 months) and long-term follow-up (LT-FU, range 93–197 months). Quality of life and mood were evaluated using the SF36 and Beck Depression Index (BDI) questionnaires.

Results

Patients reached an improvement in motor symptoms of 63.8 ± 5.7% (mean ± SE) at ST-FU and 67.9 ± 6.1% at LT-FU. Moreover, a significant and stable reduction in disability was shown following DBS (54.2 ± 9.4% at ST-FU and 53.8 ± 9.2% at LT-FU). BDI and SF36 had improved by 40% and 23%, respectively, at LT-FU (n = 14). Stimulation-induced adverse events included swallowing difficulties, dysarthria, and bradykinesia. Pulse generator (n = 3) and electrodes (n = 5) were revised in seven patients due to infection.

Conclusions

Pallidal DBS is a safe and efficacious long-term treatment for dystonia with sustained effects on motor impairment and disability, accompanied by a robust improvement in mood and quality of life.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09745-z) contains supplementary material, which is available to authorized users.

Treatable Inherited Movement Disorders in Children: Spotlight on Clinical and Biochemical Features

Background

About 80% of monogenic metabolic diseases causing movement disorders (MDs) emerges during the first 2 decades of life, and a number of these conditions offers the opportunity of a disease-modifying treatment. The implementation of enlarged neonatal screening programs and the impressive rapid increase of the identification of new conditions are enhancing our potential to recognize and treat several diseases causing MDs, changing their outcome and phenotypic spectrum.

Methods and Findings

A literature review of monogenic disorders causing MDs amenable to treatment was conducted focusing on early clinical signs and diagnostic biomarkers. A classification in 3 broad categories based on the therapeutic approach has been proposed. Some disorders result in irreversible neurotoxic lesions that can only be prevented if treated in a presymptomatic stage, and others present with a progressive neurological impairment that a timely diagnosis and treatment may reverse or improve. Some MDs are the result of the failure of intracellular energy supply or altered glucose transport. The treatment in these conditions includes vitamins or a metabolic shift from a carbohydrate to a fatty acid catabolism, respectively. Finally, a group of highly treatable MDs are the result of defects of neurotransmitter metabolism. In these disorders, the supplementation of precursors or mimetics of neurotransmitters can deeply change the disease natural history.

Conclusions

To prevent serious and irreversible neurological impairment, the diagnostic work-up of MDs in children should consider a number of clinical red flags and biomarkers denoting specifically treatable diseases.

Decreased number of striatal cholinergic interneurons and motor deficits in dopamine receptor 2-expressing-cell-specific Dyt1 conditional knockout mice

DYT1 early-onset generalized torsion dystonia is a hereditary movement disorder characterized by abnormal postures and repeated movements. It is caused mainly by a heterozygous trinucleotide deletion in DYT1/TOR1A, coding for torsinA. The mutation may lead to a partial loss of torsinA function. Functional alterations of the basal ganglia circuits have been implicated in this disease. Striatal dopamine receptor 2 (D2R) levels are significantly decreased in DYT1 dystonia patients and in the animal models of DYT1 dystonia. D2R-expressing cells, such as the medium spiny neurons in the indirect pathway, striatal cholinergic interneurons, and dopaminergic neurons in the basal ganglia circuits, contribute to motor performance. However, the function of torsinA in these neurons and its contribution to the motor symptoms is not clear. Here, D2R-expressing-cell-specific Dyt1 conditional knockout (d2KO) mice were generated and in vivo effects of torsinA loss in the corresponding cells were examined. The Dyt1 d2KO mice showed significant reductions of striatal torsinA, acetylcholine metabolic enzymes, Tropomyosin receptor kinase A (TrkA), and cholinergic interneurons. The Dyt1 d2KO mice also showed significant reductions of striatal D2R dimers and tyrosine hydroxylase without significant alteration in striatal monoamine contents or the number of dopaminergic neurons in the substantia nigra. The Dyt1 d2KO male mice showed motor deficits in the accelerated rotarod and beam-walking tests without overt dystonic symptoms. Moreover, the Dyt1 d2KO male mice showed significant correlations between striatal monoamines and locomotion. The results suggest that torsinA in the D2R-expressing cells play a critical role in the development or survival of the striatal cholinergic interneurons, expression of striatal D2R mature form, and motor performance. Medical interventions to compensate for the loss of torsinA function in these neurons may affect the onset and symptoms of this disease.

Recording Electrical Brain Activity with Novel Stretchable Electrodes Based on Supersonic Cluster Beam Implantation Nanotechnology on Conformable Polymers

Background

Multielectrodes are implanted in central and peripheral nervous systems for rehabilitation and diagnostic purposes. The physical resistance of intracranial devices to mechanical stress is critical and fractures or electrode displacement may occur. We describe here a new recording device with stretchable properties based on Supersonic Cluster Beam Implantation (SCBI) technology with high mechanical adaptability to displacement and movement.

Results

The capability of SCBI-based multichannel electrodes to record brain electrical activity was compared to glass/silicon microelectrodes in acute in vitro experiments on the isolated guinea pig brain preparation. Field potentials and power frequency analysis demonstrated equal recording features for SCBI and standard electrodes. Chronic in vivo epidural implantation of the SCBI electrodes confirmed excellent long-term recording properties in comparison to standard EEG metal electrodes. Tissue biocompatibility was demonstrated by neuropathological evaluation of the brain tissue 2 months after the implantation of the devices in the subarachnoid space.

Conclusion

We confirm the biocompatibility of novel SCBI-based stretchable electrode devices and demonstrate their suitability for recording electrical brain activity in pre-clinical settings.

Pallidal Deep Brain Stimulation in DYT6 Dystonia: Clinical Outcome and Predictive Factors for Motor Improvement

Pallidal deep brain stimulation is an established treatment in dystonia. Available data on the effect in DYT-THAP1 dystonia (also known as DYT6 dystonia) are scarce and long-term follow-up studies are lacking. In this retrospective, multicenter follow-up case series of medical records of such patients, the clinical outcome of pallidal deep brain stimulation in DYT-THAP1 dystonia, was evaluated. The Burke Fahn Marsden Dystonia Rating Scale served as an outcome measure. Nine females and 5 males were enrolled, with a median follow-up of 4 years and 10 months after implant. All benefited from surgery: dystonia severity was reduced by a median of 58% (IQR 31-62, p = 0.001) at last follow-up, as assessed by the Burke Fahn Marsden movement subscale. In the majority of individuals, there was no improvement of speech or swallowing, and overall, the effect was greater in the trunk and limbs as compared to the cranio-cervical and orolaryngeal regions. No correlation was found between disease duration before surgery, age at surgery, or preoperative disease burden and the outcome of deep brain stimulation. Device- and therapy-related side-effects were few. Accordingly, pallidal deep brain stimulation should be considered in clinically impairing and pharmaco-resistant DYT-THAP1 dystonia. The method is safe and effective, both short- and long-term.

Quality of life outcomes after deep brain stimulation in dystonia: A systematic review

Dystonia is an incurable movement disorder which can cause not only physical but also mental problems, leading to impaired health-related quality of life (HRQoL). For patients with dystonia refractory to medical treatment, deep brain stimulation (DBS) is a well-established surgical treatment. The objective of this systematic review is to provide a better understanding of HRQoL outcomes after DBS for dystonia. A search of the literature was conducted using Medline (PubMed), Embase, and Cochrane Library databases in May 2019. HRQoL outcomes after DBS along with motor outcomes were reported in a total of 36 articles involving 610 patients: 21 articles on inherited or idiopathic isolated dystonia, 5 on tardive dystonia, 3 on cerebral palsy, 2 on myoclonus-dystonia, 1 on X-linked dystonia-parkinsonism, and 3 on mixed cohorts of different dystonia subtypes. DBS improved motor symptoms in various subtypes of dystonia. Most studies on patients with inherited or idiopathic isolated dystonia showed significant improvement in physical QoL, whereas gains in mental QoL were less robust and likely related to the complexity of associated neuropsychiatric problems. HRQoL outcomes beyond 5 years remain scarce. Although the studies on patients with other subtypes of dystonia also demonstrated improvement in HRQoL after DBS, the interpretation is difficult because of a limited number of articles with small cohorts. Most articles employed generic measures (e.g. Short Form Health Survey-36) and this highlights the critical need to develop and to utilize sensitive and disease-specific HRQoL measures. Finally, long-term HRQoL outcomes and predictors of HRQoL should also be clarified.

Meta-Regression Analysis of the Long-Term Effects of Pallidal and Subthalamic Deep Brain Stimulation for the Treatment of Isolated Dystonia

OBJECTIVE

The globus pallidus internus (GPi) and subthalamic nucleus (STN) are therapeutic targets for deep brain stimulation (DBS) in the treatment of isolated dystonia. We conducted a meta-regression analysis on long-term studies of bilateral DBS in the GPi and STN to compare the relative effects of the 2 approaches.

METHODS

We systematically searched the PubMed, Embase, and Cochrane Controlled Register of Trials databases to identify studies reporting the treatment outcomes of GPi DBS and STN DBS for isolated dystonia. The primary outcome measure was the change in the Burke-Fahn-Marsden dystonia rating scale movement score between the baseline and follow-up evaluations. We performed a regression analysis using a random effects model.

RESULTS

A total of 42 follow-up evaluations (30 for GPi and 12 for STN) nested in 19 studies (16 of GPi and 3 of STN) were included in our analysis. The results from univariate regression analysis suggested that shorter disease duration and STN stimulation were associated with a greater standardized change in the Burke-Fahn-Marsden dystonia rating scale movement score. On combining the factors into 1 model, only the disease duration remained significant. The regression analysis results of the GPi and STN subgroups revealed more persistent improvement after STN stimulation.

CONCLUSIONS

A shorter disease duration correlated positively with better DBS outcomes. The STN appeared to be an optimized stimulation target for the treatment of isolated dystonia, although randomized controlled trials are needed to compare the treatment efficacy of GPi DBS and STN DBS.

Importance of the initial response to GPi deep brain stimulation in dystonia: A nine year quality of life study

BACKGROUND

Long-term efficacy of deep brain stimulation (DBS) on health-related quality-of-life (HRQoL) for isolated dystonia is not well established. This study aims to determine the long-term impact of DBS on HRQoL outcomes and identify clinical predictors.

METHODS

We retrospectively investigated 16 inherited or idiopathic isolated dystonia patients treated with bilateral globus pallidus internus DBS who were followed beyond 9 years at our center. The cohort consisted of 9 males, 7 females; 10 generalized, 6 segmental; mean (range) age at implantation, 37.0 (8-67) years; mean follow-up duration after implantation, 10.9 (9-13) years. We employed the Unified Dystonia Rating Scale for motor and Short Form Health Survey for HRQoL assessments to monitor the change longitudinally. We analyzed the changes in motor and HRQoL at 1-2 years (short-term) and ≥9 years (long-term) follow-up as compared to baseline with a Wilcoxon signed-rank test. We assessed the factors that predicted motor and HRQoL improvement with univariate regression analyses.

RESULTS

Motor (41.6%; p = 0.004) and HRQoL (total score, p = 0.039) improvements remained significant at long-term follow-up and, in the regression analysis, change in HRQoL outcomes correlated significantly with change in motor outcomes (R² = 0.384, p = 0.010). Additionally, short-term motor and HRQoL improvements predicted the long-term motor (R² = 0.384, p = 0.010) and HRQoL (total score, R² = 0.594, p < 0.001) outcomes, respectively.

CONCLUSION

Motor and HRQoL improvements with DBS in isolated dystonia remain sustained for nearly a decade and may largely be predictable by the short-term response to DBS.

Long-term outcome of pallidal stimulation for Meige syndrome

OBJECTIVE Meige syndrome is characterized by blepharospasm and varied subphenotypes of craniocervical dystonia. Current literature on pallidal surgery for Meige syndrome is limited to case reports and a few small-scale studies. The authors investigated the clinical outcomes of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in patients with Meige syndrome. METHODS Sixteen patients who underwent GPi DBS at the Tokyo Women's Medical University Hospital between 2002 and 2015 were included in this study. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) movement subscale (BFMDRS-M) scores (range 0-120) obtained at the following 3 time points were included in this analysis: before surgery, 3 months after surgery, and at the most recent follow-up evaluation. RESULTS The patients' mean age (± SD) at symptom onset was 46.7 ± 10.1 years, and the mean disease duration at the time of the authors' initial evaluation was 5.9 ± 4.1 years. In 12 patients, the initial symptom was blepharospasm, and the other 4 patients presented with cervical dystonia. The mean postoperative follow-up period was 66.6 ± 40.7 months (range 13-150 months). The mean total BFMDRS-M scores at the 3 time points were 16.3 ± 5.5, 5.5 ± 5.6 (66.3% improvement, p < 0.001), and 6.7 ± 7.3 (58.9% improvement, p < 0.001). CONCLUSIONS The results indicate long-term efficacy for GPi DBS for the majority of patients with Meige syndrome.

Surgical treatment of dystonia

INTRODUCTION

Treatment of dystonia should be individualized and tailored to the specific needs of patients. Surgical treatment is an important option in medically refractory cases. Several issues regarding type of the surgical intervention, targets, and predict factors of benefit are still under debate. Areas covered: To date, several clinical trials have proven the benefit and safety of deep brain stimulation (DBS) for inherited and idiopathic isolated dystonia, whereas there is still insufficient evidence in combined and acquired dystonia. The globus pallidus internus (GPi) is the target with the best evidence, but data on the subthalamic nucleus seems also to be promising. Evidence suggests that younger patients with shorter disease duration experience greater benefit following DBS. Pallidotomy and thalamotomy are currently used in subset of carefully selected patients. The development of MRI-guided focused ultrasound might bring new options to ablation approach in dystonia. Expert commentary: GPi-DBS is effective and safe in isolated dystonia and should not be delayed when symptoms compromise quality of life and functionality. Identifying the best candidates to surgery on acquired and combined dystonias is still necessary. New insights about pathophysiology of dystonia and new technological advances will undoubtedly help to tailor surgery and optimize clinical effects.

Pallidal deep brain stimulation for dystonia: a long term study

BACKGROUND

Pallidal deep brain stimulation (globus pallidus internus (GPi) DBS) is the best therapeutic option for disabling isolated idiopathic (IID) and inherited (INH) dystonia. Acquired dystonia (AD) may also benefit from GPi DBS. Efficacy and safety in the long-term remained to be established.

OBJECTIVE

To retrospectively assess long-term clinical outcomes and safety in dystonic patients who underwent GPi DBS.

METHODS

Patients were videotaped and assessed preoperatively and postoperatively (1-year and at last available follow-up) using the Burke-Fahn-Marsden Dystonia Rating Scale (motor score (BFMDRS-M); disability score (BFMDRS-D)).

RESULTS

Sixty-one patients were included (follow-up 7.9±5.9 years; range 1-20.7). In IID and INH (n=37), the BFMDRS-M improved at first (20.4±24.5; p<0.00001) and last (22.2±18.2; p<0.001) follow-ups compared with preoperatively (50.5±28.0). In AD (n=19), the BFMDRS-M ameliorated at 1-year (40.8±26.5; p<0.02) and late follow-ups (44.3±24.3; p<0.04) compared with preoperatively (52.8±24.2). In INH dystonia with other neurological features (n=4) there was no motor benefit. In IID and INH, the BFMDRS-D improved at 1-year (9.5±7.5; p<0.0002) and late follow-ups (10.4±7.8; p<0.016) compared with preoperatively (13.3±6.9). In AD, the BFMDRS-D reduced at 1-year (12.0±8.1; p<0.01) and late follow-ups (12.7 ±6.1; p=0.2) compared with preoperatively (14.35±5.7). Most adverse events were hardware related.

CONCLUSIONS

GPi DBS is an effective and safe treatment in most patients with dystonia.

Long-term clinical outcome of bilateral pallidal stimulation for intractable craniocervical dystonia (Meige syndrome). Report of 6 patients

BACKGROUND

The aim of the present study was to report the short-term as well long-term results of bilateral pallidal stimulation in 6 consecutive patients for severe debilitating craniocervical dystonia (Meige syndrome) using Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS).

METHODS

We evaluated 6 consecutive patients with the diagnosis of intractable long-standing craniocervical dystonia. The formal objective assessment included the motor and disability BFMDRS scores. The BFMDRS assessment was performed before and after it roughly annually up to 60months when bilateral pallidal stimulation was switched on and compared to baseline BFMDRS scores. We present short-term (3months postoperatively) follow-up as well long-term (from 6 to 60months) results. Baseline BFMDRS scores and subsequent follow-up BFMDRS scores were compared with the use of a Wilcoxon signed-rank test for matched pairs. A two-tailed probability level of 5% (p<0.05) was considered significant.

RESULTS

Bilateral GPi DBS improved the BFMDRS total movement score by 65% at short-term follow-up and by 53% at long-term follow-up when compared to baseline scores. Subscores for eyes at short-term follow-up were reduced by 78%, for mouth by 58%, and for speech/swallowing by 49%. This improvements for individual subscores were maintained at long-term follow-up and were as follows for eyes by 67%, mouth by 50% and speech/swallowing by 39%. The BFMDRS disability score was reduced by 48% at short-term follow-up and by 55% at long-term follow-up when compared to baseline scores.

CONCLUSION

Our results showed that bilateral GPi DBS in craniocervical dystonia is effective and safe. Phasic dystonic movements like blepharospasm or oromandibular dystonia responded very fast and favorable to pallidal stimulation reducing disabilities.

Causes of failure of pallidal deep brain stimulation in cases with pre-operative diagnosis of isolated dystonia

INTRODUCTION

Pallidal deep brain stimulation (GPi-DBS) is an effective therapy for isolated dystonia, but 10-20% of patients show improvement below 25-30%. We here investigated causes of insufficient response to GPi-DBS in isolated dystonia in a cross-sectional study.

METHODS

Patients with isolated dystonia at time of surgery, and <30% improvement on the Burke-Fahn-Marsden dystonia-rating-scale (BFMDRS) after ≥6 months of continuous GPi-DBS were videotaped ON and OFF stimulation, and history, preoperative videos, brain MRI, medical records, stimulation settings, stimulation system integrity, lead location, and genetic information were obtained and reviewed by an expert panel.

RESULTS

22 patients from 11 centres were included (8 men, 14 women; 9 generalized, 9 segmental, 3 focal, 1 bibrachial dystonia; mean (range): age 48.7 (25-72) years, disease duration 22.0 (2-40) years, DBS duration 45.5 (6-131) months). Mean BFMDRS-score was 31.7 (4-93) preoperatively and 32.3 (5-101) postoperatively. Half of the patients (n = 11) had poor lead positioning alone or in combination with other problems (combined with: other disease n = 6, functional dystonia n = 1, other problems n = 2). Other problems were disease other than isolated inherited or idiopathic dystonia (n = 5), fixed deformities (n = 2), functional dystonia (n = 3), and other causes (n = 1). Excluding patients with poor lead location from further analysis, non-isolated dystonia accounted for 45.5%, functional dystonia for 27.3%, and fixed deformities for 18.2%. In patients with true isolated dystonia, lead location was the most frequent problem.

CONCLUSION

After exclusion of lead placement and stimulation programming issues, non-isolated dystonia, functional dystonia and fixed deformities account for the majority of GPi-DBS failures in dystonia.