Outcome predictors of pallidal stimulation in patients with primary dystonia: the role of disease duration

Efficacy of deep brain stimulation in treating monogenic dystonia symptoms: protocol for a systematic review

INTRODUCTION

Complexity leads to some dystonias being considered as rare diseases with scarce synthesised evidence. Despite the deficit of scientific evidence, deep brain stimulation (DBS) is currently an effective treatment for dystonias using different brain targets, providing significant improvement of dystonic symptoms regardless of their cause. However, there is considerable variability and non-response rate due to factors such as classification, semiology, duration, aetiology and genetic cause of the disease. This protocol presents the methodology of a planned systematic review to assess the efficacy of DBS as a treatment for monogenic dystonia symptoms, a broad spectrum of pathogenic dystonias due to variants in single genes not yet explored.

METHODS AND ANALYSIS

This protocol follows the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols guidelines. With the aim to test the efficacy of DBS in monogenic dystonias, the research question in population, intervention, comparator and outcomes format will cover patients with monogenic dystonia treated with DBS with a minimum of 3 months' follow-up after surgery. The outcomes will be assessed using generic and specific scales to measure the efficacy and safety of the intervention. The search will be performed in generic and specific databases and bibliographic resources from 2000. We will include systematic reviews, randomised controlled trials and primary studies in English. In this protocol, the initial search strategy in MEDLINE is presented. Additionally, the protocol provides a description of the prospective assessment of the risk of bias in the selected studies. If studies appear homogeneous and the sample of patients is sufficiently large, a meta-analysis and a subgroup analysis are planned.

ETHICS AND DISSEMINATION

Ethics committee approval is not required. The results of the review will be published through an open access journal.

PROSPERO REGISTRATION NUMBER

CRD42023448145.

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.

Sustained quality-of-life improvements over 10 years after subthalamic nucleus deep brain stimulation for isolated dystonia

BACKGROUND

Bilateral deep brain stimulation (DBS) of subthalamic nucleus (STN) has demonstrated efficacy for ameliorating medication-refractory isolated dystonia. Nonetheless, the paucity of evidence regarding its long-term impact on quality-of-life (QoL) necessitates further investigation.

OBJECTIVES

This study aimed to elucidate the longitudinal effects of chronic STN stimulation on QoL in patients suffering from isolated dystonia.

METHODS

We enrolled 54 subjects diagnosed with isolated dystonia who underwent STN-DBS and maintained post-operative status for over 5 years. The 36-item Short Form General Health Survey (SF-36) assessed QoL, while the Montreal Cognitive Assessment (MoCA) evaluated cognitive functioning.

RESULTS

The average follow-up since implantation extended to 10.9 years. The data analysis revealed a significant enhancement in QoL following STN-DBS treatment, as Physical Component Summary (PCS), Mental Component Summary (MCS), and Global scores demonstrated substantial improvement from pre-DBS to post-DBS (p < 0.0001). The disease classifications yielded differential results; patients with generalized dystonia exhibited superior improvements in PCS (p = 0.0053) and Global scores (p = 0.0120) compared to other types. Patients aged < 36 at the time of implantation experienced greater improvements in PCS (p = 0.0109) and global scores (p = 0.0057) than older counterparts. Cognitive function, as per the MoCA scale, showed no significant difference between pre- and post-operative scores (p = 0.08).

CONCLUSIONS

STN-DBS appears to confer enduring improvements to the QoL in dystonia patients, persisting an average of 10 years or more post-surgery. These findings underscore the long-term efficacy of STN-DBS for isolated dystonia and highlight the influence of patient age and disease classification on outcomes.

Patient Selection for Deep Brain Stimulation for Pantothenate Kinase-Associated Neurodegeneration

Clinical Vignette

A 23-year-old woman with pantothenate kinase-associated neurodegeneration (PKAN) presented with medication-refractory generalized dystonia and an associated gait impairment.

Clinical Dilemma

Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) can be an effective treatment for dystonia. However, outcomes for PKAN DBS have been variable and there are no standardized criteria for patient selection.

Clinical Solution

Bilateral GPi DBS implantation resulted in improvement in dystonia and gait. The benefit has persisted over one year after implantation.

Gap in Knowledge

PKAN is a rare neurodegenerative disorder and evidence supporting the use of PKAN DBS has been largely limited to case reports and case series. Consequently, there is a paucity of long-term data, especially on gait-related outcomes.

Expert Commentary

The clinical characteristics of dystonia that respond to DBS tend to respond in PKAN. Clinicians counselling patients about the effects of DBS for PKAN should thoughtfully discuss gait and postural instability as important aspects to consider, especially as the disease will progress post-DBS.

A retrospective, naturalistic study of deep brain stimulation and vagal nerve stimulation in young patients

INTRODUCTION

Invasive neuromodulation interventions such as deep brain stimulation (DBS) and vagal nerve stimulation (VNS) are important treatments for movement disorders and epilepsy, but literature focused on young patients treated with DBS and VNS is limited. This retrospective study aimed to examine naturalistic outcomes of VNS and DBS treatment of epilepsy and dystonia in children, adolescents, and young adults.

METHODS

We retrospectively assessed patient demographic and outcome data that were obtained from electronic health records. Two researchers used the Clinical Global Impression scale to retrospectively rate the severity of neurologic and psychiatric symptoms before and after patients underwent surgery to implant DBS electrodes or a VNS device. Descriptive and inferential statistics were used to examine clinical effects.

RESULTS

Data from 73 patients were evaluated. Neurologic symptoms improved for patients treated with DBS and VNS (p < .001). Patients treated with DBS did not have a change in psychiatric symptoms, whereas psychiatric symptoms worsened for patients treated with VNS (p = .008). The frequency of postoperative complications did not differ between VNS and DBS groups.

CONCLUSION

Young patients may have distinct vulnerabilities for increased psychiatric symptoms during treatment with invasive neuromodulation. Child and adolescent psychiatrists should consider a more proactive approach and greater engagement with DBS and VNS teams that treat younger patients.

Electrophysiological insights into deep brain stimulation of the network disorder dystonia

Deep brain stimulation (DBS), a treatment for modulating the abnormal central neuronal circuitry, has become the standard of care nowadays and is sometimes the only option to reduce symptoms of movement disorders such as dystonia. However, on the one hand, there are still open questions regarding the pathomechanisms of dystonia and, on the other hand, the mechanisms of DBS on neuronal circuitry. That lack of knowledge limits the therapeutic effect and makes it hard to predict the outcome of DBS for individual dystonia patients. Finding electrophysiological biomarkers seems to be a promising option to enable adapted individualised DBS treatment. However, biomarker search studies cannot be conducted on patients on a large scale and experimental approaches with animal models of dystonia are needed. In this review, physiological findings of deep brain stimulation studies in humans and animal models of dystonia are summarised and the current pathophysiological concepts of dystonia are discussed.

Cerebellar gray matter alterations predict deep brain stimulation outcomes in Meige syndrome

BACKGROUND

The physiopathologic mechanism of Meige syndrome (MS) has not been clarified, and neuroimaging studies centering on cerebellar changes in MS are scarce. Moreover, even though deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been recognized as an effective surgical treatment for MS, there has been no reliable biomarker to predict its efficacy.

OBJECTIVE

To characterize the volumetric alterations of gray matter (GM) in the cerebellum in MS and to identify GM measurements related to a good STN-DBS outcome.

METHODS

We used voxel-based morphometry and lobule-based morphometry to compare the regional and lobular GM differences in the cerebellum between 47 MS patients and 52 normal human controls (HCs), as well as between 31 DBS responders and 10 DBS non-responders. Both volumetric analyses were achieved using the Spatially Unbiased Infratentorial Toolbox (SUIT). Further, we performed partial correlation analyses to probe the relationship between the cerebellar GM changes and clinical scores. Finally, we plotted the receiver operating characteristic (ROC) curve to select biomarkers for MS diagnosis and DBS outcomes prediction.

RESULTS

Compared to HCs, MS patients had GM atrophy in lobule Crus I, lobule VI, lobule VIIb, lobule VIIIa, and lobule VIIIb. Compared to DBS responders, DBS non-responders had lower GM volume in the left lobule VIIIb. Moreover, partial correlation analyses revealed a positive relationship between the GM volume of the significant regions/lobules and the symptom improvement rate after DBS surgery. ROC analyses demonstrated that the GM volume of the significant cluster in the left lobule VIIIb could not only distinguish MS patients from HCs but also predict the outcomes of STN-DBS surgery with high accuracy.

CONCLUSION

MS patients display bilateral GM shrinkage in the cerebellum relative to HCs. Regional GM volume of the left lobule VIIIb can be a reliable biomarker for MS diagnosis and DBS outcomes prediction.

Elective and Emergency Deep Brain Stimulation in Refractory Pediatric Monogenetic Movement Disorders Presenting with Dystonia: Current Practice Illustrated by Two Cases

BACKGROUND

Dystonia is characterized by sustained or intermittent muscle contractions, leading to abnormal posturing and twisting movements. In pediatric patients, dystonia often negatively influences quality of life. Pharmacological treatment for dystonia is often inadequate and causes adverse effects. Deep brain stimulation (DBS) appears to be a valid therapeutic option for pharmacoresistant dystonia in children.

METHODS

To illustrate the current clinical practice, we hereby describe two pediatric cases of monogenetic movement disorders presenting with dystonia and treated with DBS. We provide a literature review of similar previously described cases and on different clinical aspects of DBS in pediatric dystonia.

RESULTS

The first patient, a 6-year-old girl with severe dystonia, chorea, and myoclonus due to an ADCY5 gene mutation, received DBS in an elective setting. The second patient, an 8-year-old boy with GNAO1-related dystonia and chorea, underwent emergency DBS due to a pharmacoresistant status dystonicus. A significant amelioration of motor symptoms (65% on the Burke-Fahn-Marsden Dystonia Rating Scale) was observed postoperatively in the first patient and her personal therapeutic goals were achieved. DBS was previously reported in five patients with ADCY5-related movement disorders, of which three showed objective improvement. Emergency DBS in our second patient resulted in the successful termination of his GNAO1-related status dystonicus, this being the eighth case reported in the literature.

CONCLUSION

DBS can be effective in monogenetic pediatric dystonia and should be considered early in the disease course. To better evaluate the effects of DBS on patients' functioning, patient-centered therapeutic goals should be discussed in a multidisciplinary approach.

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.

Both subthalamic and pallidal deep brain stimulation are effective for GNAO1-associated dystonia: three case reports and a literature review

Background

Mutations in the G-protein subunit alpha o1 (GNAO1) gene have recently been shown to be involved in the pathogenesis of early infantile epileptic encephalopathy and movement disorders. The clinical manifestations of GNAO1-associated movement disorders are highly heterogeneous. However, the genotype-phenotype correlations in this disease remain unclear, and the treatments for GNAO1-associated movement disorders are still limited.

Objective

The objective of this study was to explore diagnostic and therapeutic strategies for GNAO1-associated movement disorders.

Methods

This study describes the cases of three Chinese patients who had shown severe and progressive dystonia in the absence of epilepsy since early childhood. We performed genetic analyses in these patients. Patients 1 and 2 underwent globus pallidus internus (GPi) deep brain stimulation (DBS) implantation, and Patient 3 underwent subthalamic nucleus (STN) DBS implantation. In addition, on the basis of a literature review, we summarized and discussed the clinical characteristics and outcomes after DBS surgery for all reported patients with GNAO1-associated movement disorders.

Results

Whole-exome sequencing (WES) analysis revealed de novo variants in the GNAO1 gene for all three patients, including a splice-site variant (c.724-8G > A) in Patients 1 and 3 and a novel heterozygous missense variant (c.124G > A; p. Gly42Arg) in Patient 2. Both GPi and STN DBS were effective in improving the dystonia symptoms of all three patients.

Conclusion

DBS is effective in ameliorating motor symptoms in patients with GNAO1-associated movement disorders, and both STN DBS and GPi DBS should be considered promptly for patients with sustained refractory GNAO1-associated dystonia.

Long-Term Outcomes of Deep Brain Stimulation for Pediatric Dystonia

BACKGROUND

Deep brain stimulation (DBS) has been utilized for over two decades to treat medication-refractory dystonia in children. Short-term benefit has been demonstrated for inherited, isolated, and idiopathic cases, with less efficacy in heredodegenerative and acquired dystonia. The ongoing publication of long-term outcomes warrants a critical assessment of available information as pediatric patients are expected to live most of their lives with these implants.

SUMMARY

We performed a review of the literature for data describing motor and neuropsychiatric outcomes, in addition to complications, 5 or more years after DBS placement in patients undergoing DBS surgery for dystonia at an age younger than 21. We identified 20 articles including individual data on long-term motor outcomes after DBS for a total of 78 patients. In addition, we found five articles reporting long-term outcomes after DBS in 9 patients with status dystonicus. Most patients were implanted within the globus pallidus internus, with only a few cases targeting the subthalamic nucleus and ventrolateral posterior nucleus of the thalamus. The average follow-up was 8.5 years, with a range of up to 22 years. Long-term outcomes showed a sustained motor benefit, with median Burke-Fahn-Marsden dystonia rating score improvement ranging from 2.5% to 93.2% in different dystonia subtypes. Patients with inherited, isolated, and idiopathic dystonias had greater improvement than those with heredodegenerative and acquired dystonias. Sustained improvements in quality of life were also reported, without the development of significant cognitive or psychiatric comorbidities. Late adverse events tended to be hardware-related, with minimal stimulation-induced effects.

KEY MESSAGES

While data regarding long-term outcomes is somewhat limited, particularly with regards to neuropsychiatric outcomes and adverse events, improvement in motor outcomes appears to be preserved more than 5 years after DBS placement.

DIPS (Dystonia Image-based Programming of Stimulation: a prospective, randomized, double-blind crossover trial)

Introduction

Deep brain stimulation of the internal globus pallidus is an effective treatment for dystonia. However, there is a large variability in clinical outcome with up to 25% non-responders even in highly selected primary dystonia patients. In a large cohort of patients we recently demonstrated that the variable clinical outcomes of pallidal DBS for dystonia may result to a large degree by the exact location and stimulation volume within the pallidal region. Here we test a novel approach of programing based on these insights: we first defined probabilistic maps of anti-dystonic effects by aggregating individual electrode locations and volumes of tissue activated of > 80 patients collected in a multicentre effort. We subsequently modified the algorithms to be able to test all possible stimulation settings of de novo patients in silico based on the expected clinical outcome and thus potentially predict the best possible stimulation parameters for the individual patients.

Methods

Within the framework of a BMBF-funded study, this concept of a computer-based prediction of optimal stimulation parameters for patients with dystonia will be tested in a randomized, controlled crossover study. The main parameter for clinical efficacy and primary endpoint is based on the blinded physician rating of dystonia severity reflected by Clinical Dystonia Rating Scales for both interventions (best clinical settings and model predicted settings) after 4 weeks of continuous stimulation. The primary endpoint is defined as “successful treatment with model predicted settings” (yes or no). The value is “yes” if the motor symptoms with model predicted settings are equal or better (tolerance 5% of absolute difference in percentages) to clinical settings. Secondary endpoints will include measures of quality of life, calculated energy consumption of the neurostimulation system and physician time for programming.

Perspective

We envision, that computer-guided deep brain stimulation programming in silico might provide optimal stimulation settings for patients with dystonia without the burden of months of programming sessions. The study protocol is designed to evaluate which programming method is more effective in controlling motor symptom severity and improving quality of life in dystonia (best clinical settings and model predicted settings).

Trial registration Registered with ClinicalTrials.gov on Oct 27, 2021 (NCT05097001).

Predicting Outcome in a Cohort of Isolated and Combined Dystonia within Probabilistic Brain Mapping

Background

Probabilistic brain mapping is a promising tool to estimate the expected benefit of pallidal deep brain stimulation (GPi‐DBS) in patients with isolated dystonia (IsoD).

Objectives

To investigate the role of probabilistic mapping in combined dystonia (ComD).

Methods

We rendered the pallidal atlas and the volume of tissue activated (VTA) for a cohort of patients with IsoD (n = 20) and ComD (n = 10) that underwent GPi‐DBS. The VTA was correlated with clinical improvement. Afterwards, each VTA was applied on the previously published probabilistic model (Reich et al., 2019). The correlation between predicted and observed clinical benefit was studied in a linear regression model.

Results

A good correlation between observed and predicted outcome was found for both patients with IsoD (n = 14) and ComD (n = 7) (r² = 0.32; P < 0.05). In ComD, 42% of the variance in DBS response is explained by VTA‐based outcome map.

Conclusion

A probabilistic model would be helpful in clinical practice to circumvent unpredictable and less impressive motor results often found in ComD.

Surgical Management for Dystonia: Efficacy of Deep Brain Stimulation in the Long Term

Introduction: Dystonia is a movement disorder substantially affecting the quality of life. Botulinum Neurotoxin (BoNT) is used intramuscularly as a treatment for dystonia; however, not all dystonia patients respond to this treatment. Deep brain stimulation (DBS) is an established treatment for Parkinson’s disease (PD) and essential tremor, but it can help in dystonia as well. Objectives: We studied a total of 67 dystonia patients who were treated with DBS over a period of 7 years to find out the long-term efficacy of DBS in those patients. First, we calculated patient improvement in post-surgery follow-up programs using the Global Dystonia Severity scale (GDS) and Burke–Fahn–Marsden dystonia rating scale (BFMDRS). Secondly, we analyzed the scales scores to see if there was any statistical significance. Methods: In our study we analyzed patients with ages from 38 to 78 years with dystonia who underwent DBS surgery between January 2014 and December 2020 in four different centers (India, Kuwait, Egypt, and Turkey). The motor response to DBS surgery was retrospectively measured for each patient during every follow-up visit using the GDS and the BFMDRS scales. Results: Five to 7 years post-DBS, the mean reduction in the GDS score was 30 ± 1.0 and for the BFMDRS score 26 ± 1.0. The longitudinal change in scores at 12 and 24 months post-op was also significant with mean reductions in GDS and BFMDRS scores of 68 ± 1.0 and 56 ± 1.0, respectively. The p-values were <0.05 for our post-DBS dystonia patients. Conclusions: This study illustrates DBS is an established, effective treatment option for patients with different dystonias, such as generalized, cervical, and various brain pathology-induced dystonias. Although symptoms are not completely eliminated, continuous improvements are noticed throughout the post-stimulation time frame.

Dystonia and Cerebellum: From Bench to Bedside

Dystonia pathogenesis remains unclear; however, findings from basic and clinical research suggest the importance of the interaction between the basal ganglia and cerebellum. After the discovery of disynaptic pathways between the two, much attention has been paid to the cerebellum. Basic research using various dystonia rodent models and clinical studies in dystonia patients continues to provide new pieces of knowledge regarding the role of the cerebellum in dystonia genesis. Herein, we review basic and clinical articles related to dystonia focusing on the cerebellum, and clarify the current understanding of the role of the cerebellum in dystonia pathogenesis. Given the recent evidence providing new hypotheses regarding dystonia pathogenesis, we discuss how the current evidence answers the unsolved clinical questions.

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.

Impaired reach-to-grasp kinematics in parkinsonian patients relates to dopamine-dependent, subthalamic beta bursts

Excessive beta-band oscillations in the subthalamic nucleus are key neural features of Parkinson’s disease. Yet the distinctive contributions of beta low and high bands, their dependency on striatal dopamine, and their correlates with movement kinematics are unclear. Here, we show that the movement phases of the reach-to-grasp motor task are coded by the subthalamic bursting activity in a maximally-informative beta high range. A strong, three-fold correlation linked beta high range bursts, imbalanced inter-hemispheric striatal dopaminergic tone, and impaired inter-joint movement coordination. These results provide new insight into the neural correlates of motor control in parkinsonian patients, paving the way for more informative use of beta-band features for adaptive deep brain stimulation devices.

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.

Correlates of deep brain stimulation consensus conference decision to treat primary dystonia

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for motor disturbance in people with primary dystonia (PWD). Numerous factors are considered by an interdisciplinary consensus conference before deciding candidacy for DBS surgery (e.g., demographic, medical, cognitive, and behavioral factors). However, little is known about which of these factors are associated with PWD DBS surgery consensus conference decisions.

OBJECTIVE

Our goal was to examine whether pre-operative demographic, medical, and cognitive/behavioral variables are associated DBS consensus conference decisions in patients with dystonia.

METHODS

Thirty-two PWD completed comprehensive presurgery workup included neurological and neuropsychological exams, and neuroimaging in consideration for DBS surgery. An interdisciplinary conference committee either recommended or did not recommend DBS surgery based upon these data. Demographic and medical data (e.g., dystonia disease characteristics, medical comorbidities, medications) were also collected. We also examined impact from cardiovascular disease factors, using a Revised Cardiac Risk Index. PWD were grouped based on DBS conference decision (eligible: n = 21, ineligible: n = 11) and compared across demographic, medical, and cognitive/behavioral variables.

RESULTS

Across clinical variables, PWD who were deemed ineligible for DBS surgery had a higher Revised Cardiac Risk Index. PWD who were classified as ineligible displayed lower global cognitive functioning, working memory, phonemic fluency, memory retrieval, and cognitive flexibility.

CONCLUSIONS

Consensus decision making regarding DBS surgery eligibility involves a multifactorial process. We found that deficits in executive functioning were associated with the DBS consensus committee decision. We also observed elevated cardiac risk among these individuals, likely reflecting the relation between vascular health and cognition. Implications, and clinical and scientific applications of these findings are discussed.

The Efficacy and Predictors of Using GPi-DBS to Treat Early-Onset Dystonia: An Individual Patient Analysis

OBJECTIVE

To compare the efficacy in patients with different genotypes, identify the potential predictive factors, and summarize the complications of globus pallidus deep brain stimulation (GPi-DBS) treating early-onset dystonia.

METHODS

Three electronic databases (PubMed, Embase, and Cochrane databases) were searched with no publication data restriction. The primary outcomes were the improvements in Burke-Fahn-Marsden Dystonia Rating Scale motor (BFMDRS-M) and disability (BFMDRS-D) score. Pearson's correlation coefficients and a metaregression analysis were used to identify the potential predictive factors. This article was registered in Prospero (CRD42020188527).

RESULTS

Fifty-four studies (231 patients) were included. Patients showed significant improvement rate in BFMDRS-M (60.6%, p < 0.001) and BFMDRS-D (57.5%, p < 0.001) scores after treatment with GPi-DBS. BFMDRS-M score improved greater in the DYT-1-positive (p = 0.001) and DYT-11-positive (p = 0.008) patients compared to DYT-6-positive patients. BFMDRS-D score improved greater in the DYT-11 (+) compared to DYT-6 (+) patients (p = 0.010). The relative change of BFMDRS-M (p = 0.002) and BFMDRS-D (p = 0.010) scores was negatively correlated with preoperative BFMDRS-M score. In the metaregression analysis, the best predictive model showed that preoperative BFMDRS-M, disease duration (p = 0.047), and the age at symptom onset (p = 0.027) were important.

CONCLUSION

Patients with early-onset dystonia have a significant effect after GPi-DBS treatment, and DYT-1 (+) and DYT-11 (+) patients are better candidates for GPi-DBS. Lower preoperative score, later age of onset, and an earlier age at surgery probably predict better clinical outcomes.

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 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.

Disease Progression of Idiopathic Cervical Dystonia in Spite of Improvement After Botulinum Toxin Therapy

Aim of the Study: To demonstrate general progression of symptoms in cervical dystonia (CD) on the one hand and improvement of some special symptoms on the other hand after botulinum toxin (BoNT) therapy. Methods: 74 patients with idiopathic CD under continuous treatment in a BoNT outpatient department with at least three injections, completed a short questionnaire. They were asked whether pain, increased muscle tone and tension, reduced mobility of the head, abnormal head position, head tremor, or other symptoms had been present at the onset of BoNT-therapy and which symptoms were present at the time of recruitment. Patients had to rate actual severity of CD in percent of the severity of CD at the onset of BoNT-therapy. The TSUI score was determined by the treating physician. Blood samples were taken to analyze induction of neutralizing antibodies. Results: Mean improvement of CD reported by the patients and scored by the physician was about 50%. The frequency of all symptoms increased with duration of therapy. The symptom most frequently improved was abnormal head position. The longer the time span between onset of symptoms and onset of BoNT-therapy was, the higher was the actual TSUI score and the lower the improvement reported. Twelve patients had positive antibody tests. Conclusions: Patients experience a progression of CD, but recognize improvement of abnormal head position due to BoNT-therapy. The longer patients have been without BoNT- therapy, the poorer is the long-term outcome independent on duration of BoNT treatment. Therefore BoNT-therapy should be initiated as early as possible.

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.

Treatment of Dystonia: Medications, Neurotoxins, Neuromodulation, and Rehabilitation

Dystonia is a complex disorder with numerous presentations occurring in isolation or in combination with other neurologic symptoms. Its treatment has been significantly improved with the advent of botulinum toxin and deep brain stimulation in recent years, though additional investigation is needed to further refine these interventions. Medications are of critical importance in forms of dopa-responsive dystonia but can be beneficial in other forms of dystonia as well. Many different rehabilitative paradigms have been studied with variable benefit. There is growing interest in noninvasive stimulation as a potential treatment, but with limited long-term benefit shown to date, and additional research is needed. This article reviews existing evidence for treatments from each of these categories. To date, there are many examples of incomplete response to available treatments, and improved therapies are needed.

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.

Characteristics of globus pallidus internus local field potentials in generalized dystonia patients with TWNK mutation

OBJECTIVE

We focused on a rare gene mutation causing dystonia in two siblings who received globus pallidus internus deep brain stimulation (GPi-DBS). The aim was to characterize the relationship between neuronal activity patterns and clinical syndromes.

METHODS

Whole exome sequencing was applied to identify the TWNK (previous symbol C10orf2) mutation; Two siblings with TWNK mutation presented as generalized dystonia with rigidity and bradykinesia; four other sporadic generalized dystonia patients underwent GPi-DBS and local field potentials (LFPs) were recorded. Oscillatory activities were illustrated with power spectra and temporal dynamics measured by the Lempel-Ziv complexity (LZC).

RESULTS

Normalized power spectra of GPi LFPs differed between patients with TWNK mutation and dystonia over the low beta bands. Patients with TWNK mutation had higher low beta power (15-27 Hz, unpaired t-test, corrected P < 0.0022) and lower LZC (15-27 Hz, unpaired t-test, P < 0.01) than other patients with generalized dystonia. On the other hand, the TWNK mutation patients showed decreased low frequency and beta oscillation in the GPi after DBS, as well as improved movement performance.

CONCLUSION

The LFPs were different in TWNK mutation dystonia siblings than other patients with generalized dystonia, which indicate the abnormal LFPs were related to symptoms rather than specific disease. In addition, the inhibited effect on oscillations also provided a potential evidence for DBS treatment on rare movement disorders.

SIGNIFICANCE

This study could potentially aid in the future development of adaptive DBS via rare disease LFPs comparison.

Differential response to pallidal deep brain stimulation among monogenic dystonias: systematic review and meta-analysis

OBJECTIVE

Genetic subtypes of dystonia may respond differentially to deep brain stimulation of the globus pallidus pars interna (GPi DBS). We sought to compare GPi DBS outcomes among the most common monogenic dystonias.

METHODS

This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses and Meta-analysis of Observational Studies in Epidemiology guidelines. We searched PubMed for studies on genetically confirmed monogenic dystonia treated with GPi DBS documenting pre-surgical and post-surgical assessments using the Burke-Fahn-Marsden Dystonia Rating Scale Motor Score (BFMMS) and Burke-Fahn-Marsden Disability Score (BFMDS). We performed (i) meta-analysis for each gene mutation; (ii) weighted ordinary linear regression analyses to compare BFMMS and BFMDS outcomes between DYT-TOR1A and other monogenic dystonias, adjusting for age and disease duration and (iii) weighted linear regression analysis to estimate the effect of age, sex and disease duration on GPi DBS outcomes. Results were summarised with mean change and 95% CI.

RESULTS

DYT-TOR1A (68%, 38.4 points; p<0.001), DYT-THAP1 (37% 14.5 points; p<0.001) and NBIA/DYT-PANK2 (27%, 21.4 points; p<0.001) improved in BFMMS; only DYT-TOR1A improved in BFMDS (69%, 9.7 points; p<0.001). Improvement in DYT-TOR1A was significantly greater than in DYT-THAP1 (BFMMS -31%), NBIA/DYT-PANK2 (BFMMS -35%; BFMDS -53%) and CHOR/DYT-ADCY5 (BFMMS -36%; BFMDS -42%). Worse motor outcomes were associated with longer dystonia duration and older age at dystonia onset in DYT-TOR1A, longer dystonia duration in DYT/PARK-TAF1 and younger age at dystonia onset in DYT-SGCE.

CONCLUSIONS

GPi DBS outcomes vary across monogenic dystonias. These data serve to inform patient selection and prognostic counselling.

Predictive factors of outcome in cervical dystonia following deep brain stimulation: an individual patient data meta-analysis

BACKGROUND

Deep brain stimulation (DBS) therapy has been suggested to be a beneficial alternative in cervical dystonia (CD) for patients who failed nonsurgical treatments. This individual patient data meta-analysis compared the efficacy of DBS in the globus pallidus internus (GPi) versus subthalamic nucleus (STN) and identified possible predictive factors for CD.

METHODS

Three electronic databases (PubMed, Embase and Web of Science) were searched for studies with no publication date restrictions. The primary outcomes were normalized by calculating the relative change in TWSTRS total scores and subscale scores at the last follow-up. Data were analyzed mainly using Pearson's correlation coefficients and a stepwise multivariate regression analysis.

RESULTS

Thirteen studies (86 patients, 58 with GPi-DBS and 28 with STN-DBS) were eligible. Patients showed significant improvement in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) (52.5 ± 11.6 vs 21.9 ± 14.9, P < 0.001) scores at the last follow-up (22.0 ± 14.3 months), compared with scores at baseline, with a mean improvement of 56.6% (P < 0.001) (54.9% in severity, 63.2% in disability, 41.7% in pain). There was no significant difference in the improvement (%) of the total TWSTRS scores in 3 years for the GPI and STN groups (58.1 ± 22.6 vs 47.5 ± 39.2, P > 0.05). Age at surgery and age at symptom onset were negatively correlated with the relative changes in TWSTRS scores at the last follow-up, while there was a positive correlation with preoperative TWSTRS scores. On the stepwise multivariate regression, only the age at surgery remained significant in the best predictive model.

CONCLUSIONS

GPi-DBS and STN-DBS both provided a common great improvement in the symptoms of CD patients in 3 years. Earlier age at surgery may probably indicate larger improvement. More randomized large-scale clinical trials are warranted in the future.

Probabilistic mapping of the antidystonic effect of pallidal neurostimulation: a multicentre imaging study

Deep brain stimulation of the internal globus pallidus is a highly effective and established therapy for primary generalized and cervical dystonia, but therapeutic success is compromised by a non-responder rate of up to 25%, even in carefully-selected groups. Variability in electrode placement and inappropriate stimulation settings may account for a large proportion of this outcome variability. Here, we present probabilistic mapping data on a large cohort of patients collected from several European centres to resolve the optimal stimulation volume within the pallidal region. A total of 105 dystonia patients with pallidal deep brain stimulation were enrolled and 87 datasets (43 with cervical dystonia and 44 with generalized dystonia) were included into the subsequent 'normative brain' analysis. The average improvement of dystonia motor score was 50.5 ± 30.9% in cervical and 58.2 ± 48.8% in generalized dystonia, while 19.5% of patients did not respond to treatment (<25% benefit). We defined probabilistic maps of anti-dystonic effects by aggregating individual electrode locations and volumes of tissue activated (VTA) in normative atlas space and ranking voxel-wise for outcome distribution. We found a significant relation between motor outcome and the stimulation volume, but not the electrode location per se. The highest probability of stimulation induced motor benefit was found in a small volume covering the ventroposterior globus pallidus internus and adjacent subpallidal white matter. We then used the aggregated VTA-based outcome maps to rate patient individual VTAs and trained a linear regression model to predict individual outcomes. The prediction model showed robustness between the predicted and observed clinical improvement, with an r2 of 0.294 (P < 0.0001). The predictions deviated on average by 16.9 ± 11.6 % from observed dystonia improvements. For example, if a patient improved by 65%, the model would predict an improvement between 49% and 81%. Results were validated in an independent cohort of 10 dystonia patients, where prediction and observed benefit had a correlation of r2 = 0.52 (P = 0.02) and a mean prediction error of 10.3% (±8.9). These results emphasize the potential of probabilistic outcome brain mapping in refining the optimal therapeutic volume for pallidal neurostimulation and advancing computer-assisted planning and programming of deep brain stimulation.

Pallidal lead placement in dystonia: leads of non-responders are contained within an anatomical range defined by responders

Background

Deep brain stimulation (DBS) within the pallidum represents an effective and well-established treatment for isolated dystonia. However, clinical outcome after surgery may be variable with limited response in 10–25% of patients. The effect of lead location on clinical improvement is still under debate.

Objective

To identify stimulated brain regions associated with the most beneficial clinical outcome in dystonia patients.

Methods

18 patients with cervical and generalized dystonia with chronic DBS of the internal pallidum were investigated. Patients were grouped according to their clinical improvement into responders, intermediate responders and non-responders. Magnetic resonance and computed tomography images were co-registered, and the volume of tissue activated (VTA) with respect to the pallidum of individual patients was analysed.

Results

VTAs in responders (n = 11), intermediate responders (n = 3) and non-responders (n = 4) intersected with the posterior internal (GPi) and external (GPe) pallidum and the subpallidal area. VTA heat maps showed an almost complete overlap of VTAs of responders, intermediate and non-responders. VTA coverage of the GPi was not higher in responders. In contrast, VTAs of intermediate and non-responders covered the GPi to a significantly larger extent in the left hemisphere (p < 0.01).

Conclusions

DBS of ventral parts of the posterior GPi, GPe and the adjacent subpallidal area containing pallidothalamic output projections resulted in favourable clinical effects. Of note, non-responders were also stimulated within the same area. This suggests that factors other than mere lead location (e.g., clinical phenotype, genetic background) have determined clinical outcome in the present cohort.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09753-z) contains supplementary material, which is available to authorized users.

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.

Functional and Structural Connectivity Patterns Associated with Clinical Outcomes in Deep Brain Stimulation of the Globus Pallidus Internus for Generalized Dystonia

BACKGROUND AND PURPOSE

Deep brain stimulation is a well-established treatment for generalized dystonia, but outcomes remain variable. Establishment of an imaging marker to guide device targeting and programming could possibly impact the efficacy of deep brain stimulation in dystonia, particularly in the absence of acute clinical markers to indicate benefit. We hypothesize that the stimulation-based functional and structural connectivity using resting-state fMRI and DTI can predict therapeutic outcomes in patients with generalized dystonia and deep brain stimulation.

MATERIALS AND METHODS

We performed a retrospective analysis of 39 patients with inherited or idiopathic-isolated generalized dystonia who underwent bilateral globus pallidus internus deep brain stimulation. After electrode localization, the volumes of tissue activated were modeled and used as seed regions for functional and structural connectivity measures using a normative data base. Resulting connectivity maps were correlated with postoperative improvement in the Unified Dystonia Rating Scale score.

RESULTS

Structural connectivity between the volumes of tissue activated and the primary sensorimotor cortex was correlated with Unified Dystonia Rating Scale improvement, while more anterior prefrontal connectivity was inversely correlated with Unified Dystonia Rating Scale improvement. Functional connectivity between the volumes of tissue activated and primary sensorimotor regions, motor thalamus, and cerebellum was most correlated with Unified Dystonia Rating Scale improvement; however, an inverse correlation with Unified Dystonia Rating Scale improvement was seen in the supplemental motor area and premotor cortex.

CONCLUSIONS

Functional and structural connectivity with multiple nodes of the motor network is associated with motor improvement in patients with generalized dystonia undergoing deep brain stimulation. Results from this study may serve as a basis for future development of clinical markers to guide deep brain stimulation targeting and programming in dystonia.

Clinical phenotypes associated with outcomes following deep brain stimulation for childhood dystonia

OBJECTIVE

Although deep brain stimulation (DBS) is an accepted treatment for childhood dystonia, there is significant heterogeneity in treatment response and few data are available to identify ideal surgical candidates.

METHODS

Data were derived from a systematic review and individual patient data meta-analysis of DBS for dystonia in children that was previously published. Outcomes were assessed using the Burke-Fahn-Marsden Dystonia Rating Scale for movement (BFMDRS-M) and for disability (BFMDRS-D). The authors used partial least squares, bootstrapping, and permutation statistics to extract patterns of contributions of specific preoperative characteristics to relationship with distinct outcomes, in all patients and in patients with primary and secondary dystonia separately.

RESULTS

Of 301 children undergoing DBS for dystonia, 167 had primary dystonia, 125 secondary dystonia, and 9 myoclonus dystonia. Three dissociable preoperative phenotypes (latent variables) were identified and associated with the following: 1) BFMDRS-M at last follow-up; 2) relative change in BFMDRS-M score; and 3) relative change in BFMDRS-D score. The phenotype of patients with secondary dystonia, with a high BFMDRS-M score and truncal involvement, undergoing DBS at a younger age, was associated with a worse postoperative BFMDRS-M score. Children with primary dystonia involving the trunk had greater improvement in BFMDRS-M and -D scores. Those with primary dystonia of shorter duration and proportion of life with disease, undergoing globus pallidus DBS, had greater improvements in BFMDRS-D scores at long-term follow-up.

CONCLUSIONS

In a comprehensive, data-driven, multivariate analysis of DBS for childhood dystonia, the authors identified novel and dissociable patient phenotypes associated with distinct outcomes. The findings of this report may inform surgical candidacy for DBS.

Deep brain stimulation for dystonia in Finland during 2007-2016

BACKGROUND

Dystonia is a movement disorder substantially affecting the quality of life and the ability to work. A proportion of patients does not respond to first line pharmacotherapy. Deep brain stimulation (DBS) is established as a primary operative treatment option for severe drug resistant dystonia. We studied dystonia patients treated with DBS in Finland between the years 2007-2016 to evaluate the use and outcomes of DBS treatment.

METHODS

We analysed the hospital records of dystonia patients, who underwent DBS operation during 2007-2016 in Finland. The clinical and technical parameters were recorded as well as preoperative assessments and treatments. The response to DBS was evaluated retrospectively using the Global Dystonia Rating Scale (GDS).

RESULTS

Out of 585 dB implantations during the study period, 37 were done for dystonia. The clinical response improved significantly with time in the isolated focal dystonia group, and at 12 months, 22 of 32 patients had over 50% alleviation of the GDS score. There was only one subclinical intracerebral haemorrhage, and four infections leading to revision. Speech impairment and limb coordination problems were common stimulation- related adverse events and were mostly resolved or relieved with the adjustment of stimulation parameters.

CONCLUSIONS

DBS seems to be beneficial in dystonia. Although DBS is indicated for dystonia in Finland, the number of operations did not increase at the same rate as DBS operations in general. DBS appears to be a safe and effective treatment for focal as well as generalized dystonia.

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.

BDNF provides many routes toward STN DBS-mediated disease modification

The concept that subthalamic nucleus deep brain stimulation (STN DBS) may be disease modifying in Parkinson's disease (PD) is controversial. Several clinical trials that enrolled subjects with late‐stage PD have come to disparate conclusions on this matter. In contrast, some clinical studies in early‐ to midstage subjects have suggested a disease‐modifying effect. Dopaminergic innervation of the putamen is essentially absent in PD subjects within 4 years after diagnosis, indicating that any neuroprotective therapy, including STN DBS, will require intervention within the immediate postdiagnosis interval. Preclinical prevention and early intervention paradigms support a neuroprotective effect of STN DBS on the nigrostriatal system via increased brain‐derived neurotrophic factor (BDNF). STN DBS‐induced increases in BDNF provide a multitude of mechanisms capable of ameliorating dysfunction and degeneration in the parkinsonian brain. A biomarker for measuring brain‐derived neurotrophic factor‐trkB signaling, though, is not available for clinical research. If a prospective clinical trial were to examine whether STN DBS is disease modifying, we contend the strongest rationale is not dependent on a preclinical neuroprotective effect per se, but on the myriad potential mechanisms whereby STN DBS‐elicited brain‐derived neurotrophic factor‐trkB signaling could provide disease modification. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Therapeutic Applications of Invasive Neuromodulation in Children and Adolescents

Although the application of noninvasive brain stimulation methods to children and adolescents has been frequently studied in depression, autism spectrum disorder, attention-deficit/hyperactivity disorder, and other neuropsychiatric disorders, invasive methods such as deep brain stimulation (DBS) and vagal nerve stimulation (VNS) have received less attention. DBS and VNS have demonstrated utility in young patients especially for dystonia and epilepsy. VNS has FDA clearance for intractable epilepsy in patients aged 4 years and older. Further measured work with invasive neuromodulation for children and adolescents with debilitating neuropsychiatric disorders could provide new treatment options and expand current knowledge base of neurocircuitry across development.

Phase matters: A role for the subthalamic network during gait

The role of the subthalamic nucleus in human locomotion is unclear although relevant, given the troublesome management of gait disturbances with subthalamic deep brain stimulation in patients with Parkinson’s disease. We investigated the subthalamic activity and inter-hemispheric connectivity during walking in eight freely-moving subjects with Parkinson’s disease and bilateral deep brain stimulation. In particular, we compared the subthalamic power spectral densities and coherence, amplitude cross-correlation and phase locking value between resting state, upright standing, and steady forward walking. We observed a phase locking value drop in the β-frequency band (≈13-35Hz) during walking with respect to resting and standing. This modulation was not accompanied by specific changes in subthalamic power spectral densities, which was not related to gait phases or to striatal dopamine loss measured with [¹²³I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane and single-photon computed tomography. We speculate that the subthalamic inter-hemispheric desynchronization in the β-frequency band reflects the information processing of each body side separately, which may support linear walking. This study also suggests that in some cases (i.e. gait) the brain signal, which could allow feedback-controlled stimulation, might derive from network activity.

Early structural and functional plasticity alterations in a susceptibility period of DYT1 dystonia mouse striatum

The onset of abnormal movements in DYT1 dystonia is between childhood and adolescence, although it is unclear why clinical manifestations appear during this developmental period. Plasticity at corticostriatal synapses is critically involved in motor memory. In the Tor1a^+/Δgag DYT1 dystonia mouse model, long-term potentiation (LTP) appeared prematurely in a critical developmental window in striatal spiny neurons (SPNs), while long-term depression (LTD) was never recorded. Analysis of dendritic spines showed an increase of both spine width and mature mushroom spines in Tor1a^+/Δgag neurons, paralleled by an enhanced AMPA receptor (AMPAR) accumulation. BDNF regulates AMPAR expression during development. Accordingly, both proBDNF and BDNF levels were significantly higher in Tor1a^+/Δgag mice. Consistently, antagonism of BDNF rescued synaptic plasticity deficits and AMPA currents. Our findings demonstrate that early loss of functional and structural synaptic homeostasis represents a unique endophenotypic trait during striatal maturation, promoting the appearance of clinical manifestations in mutation carriers.

Deep brain stimulation for monogenic dystonia

PURPOSE OF REVIEW

Deep brain stimulation (DBS) has recently emerged as an important management option in children with medically refractory dystonia. DBS is most commonly used, best studied, and thought to be most efficacious for a select group of childhood or adolescent onset monogenic dystonias (designated with a standard 'DYT' prefix). We review how to clinically recognize these types of dystonia and the relative efficacy of DBS for key monogenic dystonias.

RECENT FINDINGS

Though used for dystonia in adults for several years, DBS has only lately been used in children. Recent evidence shows that patients with shorter duration of dystonia often experience greater benefit following DBS. This suggests that early recognition of the appropriate dystonic phenotypes and consideration of DBS in these patients may improve the management of dystonia.

SUMMARY

DBS should be considered early in patients who have medically refractory dystonia, especially for the monogenic dystonias that have a high response rate to DBS. It is important to differentiate between these monogenic dystonias and dystonias of other causes to properly prognosticate for these patients and to determine whether DBS is an appropriate management option.

Motor Cortical Plasticity Relates to Symptom Severity and Clinical Benefit From Deep Brain Stimulation in Cervical Dystonia

OBJECTIVE

To investigate the relationship between motor cortical plasticity, intracortical inhibition, and clinical response to pallidal deep brain stimulation (DBS) in patients with cervical dystonia (CD).

MATERIALS AND METHODS

Response to paired associative stimulation (PAS) and short interval intracortical inhibition (SICI) were assessed in patients with CD before and after three months of DBS and correlated with severity of dystonic symptoms as assessed by Toronto-Western-Spasmodic Torticollis Rating Scale (TWSTRS) severity score. Relations of electrophysiological parameters with clinical improvement were explored with correlation analysis.

RESULTS

Patients with higher levels of plasticity before surgery showed higher symptom severity (R = 0.83, p = 0.008) but had also the larger clinical benefit following DBS (R = 0.88, p = 0.003). This correlation was independent from preoperative (preOP) TWSTRS motor score as revealed by partial correlation analysis. Intracortical inhibition was not altered in CD and not related to clinical outcome after DBS.

CONCLUSIONS

Our findings indicate that a high degree of preOP plasticity is associated with higher symptom severity, underlining the role of abnormal plasticity in the pathophysiology of dystonia. At the same time individual degree of plasticity may drive reestablishment of normal motor programs, leading to better clinical outcome with DBS. The latter suggests that individual PAS-response may indicate the susceptibility for neuromodulatory processes as an important factor for clinical DBS effects. It might therefore serve as a neurophysiological marker to predict outcome and guide patient selection.

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.