Special concerns in defining, studying, and treating dystonia in children

Clinician Knowledge, Confidence, and Practice Patterns Defining, Identifying, and Quantifying Dystonia in Children: A Cross-Sectional Survey Study

A survey was completed by 183 clinicians at a pediatric hospital to investigate knowledge, confidence, and practice patterns defining, identifying, and quantifying dystonia in children. The definition of dystonia was correctly identified by 86% of participants. While 88% reported identifying dystonia, only 42% of physicians and therapists reported quantifying dystonia. A weak, significant correlation, rs =.339, p ≤ .001, was found between years of pediatric experience and confidence identifying dystonia. Clinician reported higher confidence levels identifying and quantifying dystonia if they perform a neurological exam. Clinical training initiatives are needed to improve standardization and build confidence in defining, identifying, and quantifying dystonia.

Deep brain stimulation in pediatric dystonia: calls for therapeutic realism over nihilism

PURPOSE

Pediatric dystonia (PD) has a significant negative impact on the growth and development of the child. This study was done retrospectively to analyze functional outcomes in pediatric patients with dystonia who underwent deep brain stimulation.

METHODS

In this retrospective analytical study, all the patients of age less than 18 years undergoing deep brain stimulation (DBS) for dystonia between 2012 and 2020 in a single center were analyzed and their functional outcomes were measured by the Burke-Fahn-Marsden-dystonia-rating-scale (BFMDRS).

RESULTS

A total of 10 pediatric patients were included with a mean age of onset, duration of disease, and age at surgery being 5.75 years, 7.36 years, and 13.11 years, respectively, with a mean follow-up of 23.22 months. The mean pre-DBS motor score was 75.44 ± 23.53 which improved significantly at 6-month and 12-month follow-up to 57.27 (p value 0.004) and 50.38 (p value < 0.001), respectively. Limbs sub-scores improved significantly at both the scheduled intervals. There was a significant improvement in disability at 1-year follow-up with significant improvement in feeding, dressing, and walking components. There was a 27.34% and 36.64% improvement in dystonia with a 17.37% and 28.86% reduction in disability at 6 months and 12 months, respectively. There was a positive correlation between the absolute reduction of the motor score and improvement in disability of the patients at 6 months (rho = 0.865, p value 0.003).

CONCLUSIONS

DBS in PD has an enormous role in reducing disease burden and achieving a sustainable therapeutic goal.

Rehabilitation in childhood-onset hyperkinetic movement disorders including dystonia: Treatment change in outcomes across the ICF and feasibility of outcomes for full trial evaluation

BACKGROUND

Childhood-onset hyperkinetic movement disorders (HMD), including dystonia are notoriously difficult to treat and there are limited studies showing successful medical, surgical or non-pharmacological interventions.

METHODS

This prospective study used grouped data (n = 22) from two studies of the Cognitive Orientation to daily Occupational Performance (CO-OP) Approach for patient-selected goals. Eligibility included aged 6-21 years, deep brain stimulation in place, with manual ability classification system level I-IV. Outcome was assessed on a range of patient-reported and clinician-rated measures across the International Classification of Function at end-treatment (10 weekly sessions) (series 1 and 2) and 3-month follow-up (series 1). Feasibility of outcomes to be used in a full trial were explored.

FINDINGS

Nineteen participants completed the intervention and were included in the analysis. Of the primary outcome measures, the self-reported Canadian Occupational Performance Measure showed improvement in goal performance (mean change 4.08, 95% CI [3.37,4.79] post-; 4.18 [5.10,5.26] follow-up), and satisfaction (4.03 [3.04,5.03) post-; 4.44 [3.07,5.82] follow-up]. The Assessment of Motor and Process Skills showed improved motor score (0.52 [0.01,1.03] at follow-up only, while the process score did not change. Objective blind-rated pooled data using the Performance Quality Rating Scale-individualized indicated significant change for trained goals (3.79 [3.37,4.21] post-; (4.01,5.10) follow-up] and untrained goals (1.90 [1.24,2.55] post 1.91 [0.23,3.60] follow-up]. Motor impairment assessed by the Burke-Fahn Motor Disability Rating Scale was unchanged (-3.26 [-6.62,0.09] post-; -1.11 [-8.05,5.82] follow-up). Improvement was also observed in self-efficacy (0.97 [0.47,1.47] post-; 1.37 [1.91-0.83] follow-up) and Quality of Life (0.12 [0.03-0.22] follow-up). Goal improvement; self-efficacy and quality of life captured significant change post-intervention. This improvement was shown despite no change on impairment-related measures and were shown to be feasible measures to use in a larger study of CO-OP for this population.

Thalamic deep brain stimulation for acquired dystonia in children and young adults: a phase 1 clinical trial

OBJECTIVE

The aim of this study was to evaluate the feasibility and preliminary efficacy and safety of combined bilateral ventralis oralis posterior/ventralis intermedius (Vop/Vim) deep brain stimulation (DBS) for the treatment of acquired dystonia in children and young adults. Pallidal DBS is efficacious for severe, medication-refractory isolated dystonia, providing 50%-60% long-term improvement. Unfortunately, pallidal stimulation response rates in acquired dystonia are modest and unpredictable, with frequent nonresponders. Acquired dystonia, most commonly caused by cerebral palsy, is more common than isolated dystonia in pediatric populations and is more recalcitrant to standard treatments. Given the limitations of pallidal DBS in acquired dystonia, there is a need to explore alternative brain targets. Preliminary evidence has suggested that thalamic stimulation may be efficacious for acquired dystonia.

METHODS

Four participants, 3 with perinatal brain injuries and 1 with postencephalitic symptomatic dystonia, underwent bilateral Vop/Vim DBS and bimonthly evaluations for 12 months. The primary efficacy outcome was the change in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Barry-Albright Dystonia Scale (BADS) scores between the baseline and 12-month assessments. Video documentation was used for blinded ratings. Secondary outcomes included evaluation of spasticity (Modified Ashworth Scale score), quality of life (Pediatric Quality of Life Inventory [PedsQL] and modified Unified Parkinson's Disease Rating Scale Part II [UPDRS-II] scores), and neuropsychological assessments. Adverse events were monitored for safety.

RESULTS

All participants tolerated the procedure well, and there were no safety concerns or serious adverse events. There was an average improvement of 21.5% in the BFMDRS motor subscale score, but the improvement was only 1.6% according to the BADS score. Following blinded video review, dystonia severity ratings were even more modest. Secondary outcomes, however, were more encouraging, with the BFMDRS disability subscale score improving by 15.7%, the PedsQL total score by 27%, and the modified UPDRS-II score by 19.3%. Neuropsychological assessment findings were unchanged 1 year after surgery.

CONCLUSIONS

Bilateral thalamic neuromodulation by DBS for severe, medication-refractory acquired dystonia was well tolerated. Primary and secondary outcomes showed highly variable treatment effect sizes comparable to those of pallidal stimulation in this population. As previously described, improvements in quality of life and disability were not reflected in dystonia severity scales, suggesting a need for the development of scales specifically for acquired dystonia.Clinical trial registration no.: NCT03078816 (clinicaltrials.gov).

Bilateral polymicrogyria associated with dystonia: A new neurogenetic syndrome?

The clinical presentation of bilateral perisylvian polymicrogyria (PMG) is highly variable, including oromotor dysfunction, epilepsy, intellectual disability, and pyramidal signs. Extrapyramidal features are extremely rare. We present four apparently unrelated patients with a unique association of PMG with dystonia. The clinical, genetic, and radiologic features are described and possible mechanisms of dystonia are discussed. All patients were female and two were born to consanguineous families. All presented with early childhood onset dystonia. Other neurologic symptoms and signs classically seen in bilateral perisylvian PMG were observed, including oromotor dysfunction and speech abnormalities ranging from dysarthria to anarthria (4/4), pyramidal signs (3/4), hypotonia (3/4), postnatal microcephaly (1/4), and seizures (1/4). Neuroimaging showed a unique pattern of bilateral PMG with an infolded cortex originating primarily from the perisylvian region in three out of four patients. Whole exome sequencing was performed in two out of four patients and did not reveal pathogenic variants in known genes for cortical malformations or movement disorders. The dystonia seen in our patients is not described in bilateral PMG and suggests an underlying mechanism of impaired connectivity within the motor network or compromised cortical inhibition. The association of bilateral PMG with dystonia in our patients may represent a new neurogenetic disorder.

Mental health outcomes in children with acquired dystonia after basal ganglia stroke and associations with cognitive and motor outcomes

Pediatric arterial ischemic stroke involving the basal ganglia and/or thalamus is one of the most common causes of dystonia in children. Dystonia is a movement disorder in which excessive, involuntary muscle contractions result in twisting or repetitive movements, and abnormal posturing. The basal ganglia have been implicated in mood functioning and difficulties in these domains have been noted in adults with dystonia, yet little is currently known about these outcomes in children with dystonia following stroke. The objective of this study was to explore mental health outcomes in children with basal ganglia stroke and to determine whether children with post-stroke dystonia experience additional mental health difficulties. We also examined associations between mental health, cognitive, and motor outcomes. Participants were 75 children with stroke involving the basal ganglia and/or thalamus (dystonia n = 24, no dystonia n = 51). Results supported the presence of greater levels of anxiety and depression symptoms in children with post-stroke dystonia after stroke relative to those with similar patterns of stroke, but no dystonia. There were no significant associations between motor, cognitive, and mental health outcomes in children with post-stroke dystonia aside from depression and behavioral regulation. Motor and cognitive outcome were significantly associated in the stroke only group. These findings suggest maladaptive reorganization after stroke may contribute to motor, cognitive, and mental health outcomes in children with post-stroke dystonia, and that these outcomes are independent from one another.

Despite dystonia: natural history of delayed-onset pediatric secondary dystonia

Background: Dystonia is a movement disorder involving involuntary movements and/or postures of the limbs, trunk, neck or face. Secondary dystonia following brain injury is uncommon, with unfavorable long-term consequences. Given the limited evidence regarding pediatric secondary dystonia, this study's aim was to document the natural history of the condition and the effect of interventions on its symptomatology. Methods: We describe three cases of girls (age 8 to 11 y) who developed dystonia secondary to an acquired brain injury, received intensive rehabilitation treatments and were followed for 8-33 months post-injury. In all three cases, secondary dystonia appeared 1-3 months post-insult. Results: In none of the cases was there alleviation of dystonic symptoms over time despite physical and pharmacological interventions; in two cases the dystonic hand is now used as an assisting hand only, whereas in the third it is completely non-functional. However, despite their impairment, two girls achieved basic functional independence and one is partly independent in activities of daily living. Conclusions: Rehabilitation professionals who work with pediatric patients susceptible to developing secondary dystonia should be aware of its possible consequences and inform families and staff. Intensive task-specific training during rehabilitation may be key to regaining overall functional capabilities despite residual impairment.

Gross motor function outcomes following deep brain stimulation for childhood-onset dystonia: A descriptive report

AIM

To examine the impact of deep brain stimulation (DBS) on gross motor function in children with dystonic movement disorders.

METHOD

Prospective audit involving children implanted 2007-2015, followed for up to two years. Outcomes were evaluated across aetiological sub-groups (inherited, acquired, idiopathic) using the GMFM-88 and BFMDRS movement scale (BFM-M). The predictive value of proportion of life lived with dystonia (PLD) and baseline motor capacity were evaluated.

RESULTS

Data was available for 60 children (median surgery age 10y11mo). Inherited monogenetic dystonias demonstrated a median increase in GMFM-88 scores of 6.9% (p = 0.021) and 14.5% (p = 0.116) at one and two years. Heredodegenerative and idiopathic dystonias showed disparate responses, with non-significant changes seen in GMFM-88 and BFM-M scores, with the exception of improved one-year BFM-M scores in the idiopathic group [median change 5.5, p = 0.021]. Median GMFM-88 and BFM-M change scores were near zero for acquired dystonias, though improvement was noted in 9/18 CP cases with one-year GMFM-88 data. No significant relationship was found between PLD, or baseline GMFM-88, and GMFM-88 change following DBS.

CONCLUSION

Gross motor response to DBS is similar in profile to literature reporting results using impairment-based dystonia rating scales. Relatively consistent improvements were seen in inherited monogenetic ("primary") dystonias, while highly variable, often disappointing, gross motor responses were found in acquired, heredodegenerative, and idiopathic dystonias. In view of such response variability, alternatives to mean group studies, such as single case experimental designs with multiple replications, are needed to determine the efficacy of DBS in childhood-onset dystonias. Ongoing research is needed to identify factors that predict treatment response.

Therapeutic Applications of Noninvasive Neuromodulation in Children and Adolescents

Recent advances and growing evidence supporting the safety and efficacy of noninvasive neuromodulatory techniques in adults have facilitated the study of neuromodulation applications in children and adolescents. Noninvasive brain stimulation methods such as transcranial direct current stimulation and transcranial magnetic stimulation have been considered in children with depression, autism spectrum disorder, attention-deficit hyperactivity disorder, and other neuropsychiatric disorders. However, current clinical applications of neuromodulation techniques in children and adolescents are nascent. There is a great need for developmentally informed, large, double-blinded, randomized, controlled clinical trials to demonstrate efficacy and safety of noninvasive brain stimulation in children and adolescents.

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.

Targeted gene capture sequencing in diagnosis of dystonia patients

BACKGROUND

Dystonia is a movement disorder with high clinical and genetic heterogeneity. Molecular diagnosis is important for an accurate diagnosis of dystonia. Targeted gene capture sequencing has been an effective method for screening multiple candidate genes simultaneously. This method, however, has been rarely reported to be used with dystonia patients.

OBJECTIVES AND METHODS

To assess the effectiveness of the targeted gene capture sequencing in dystonia, we performed custom target gene capture followed by next-generation sequencing in dystonia patients from China. Sanger sequencing was utilized to substantiate the findings. The effects of identified variants were classified according to the American College of Medical Genetics and Genomics (ACMG) standards and guidelines.

RESULTS

A total of 65 patients (34 female and 31 male) were recruited in this study. The mean age at onset was 22.7 ± 13.3 years ranging from 2 to 59 years. According to ACMG standards and guidelines, of 65 patients, 12 were identified with pathogenic variants (12/65, 18.5%) in gene TOR1A, PANK2 or ATP1A3, and another four were identified with likely-pathogenic variants (4/65, 6.2%) in gene PRRT2, GCH1 or THAP1. In total, 24.6% of patients in this cohort were detected to have a genetic cause of dystonia. Another four patients (4/65, 6.2%) were identified with variants which were considered to be VUS (Variants of Uncertain Significance) in gene SGCE, TH, ANO3 and ATP1A3 respectively. The most common detected gene was TOR1A, known to be causative for DYT1 (8/65, 12.3%).

CONCLUSIONS

The study demonstrates that targeted gene capture sequencing is an effective tool for identifying the genetic cause of heterogeneous dystonia patients.

The Twists of Pediatric Dystonia: Phenomenology, Classification, and Genetics

This article aims to provide a practical review of pediatric dystonia from a clinician's perspective. The focus is on the underlying genetic causes, recent findings, and treatable conditions. Dystonia can occur in an isolated fashion or accompanied by other neurological or systemic features. The clinical presentation is often a complex overlap of neurological findings with a large differential diagnosis. We recommend an approach guided by thorough clinical evaluation, brain magnetic resonance imaging (MRI), biochemical analysis, and genetic testing to hone in on the diagnosis. This article highlights the clinical and genetic complexity of pediatric dystonia and underlines the importance of a genetic diagnosis for therapeutic considerations.

Complex care of individuals with multiple sulfatase deficiency: Clinical cases and consensus statement

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder that results in defective sulfatase post-translational modification. Sulfatases in the body are activated by a unique protein, formylglycine-generating enzyme (FGE) that is encoded by SUMF1. When FGE is absent or insufficient, all 17 known human sulfatases are affected, including the enzymes associated with metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. As such, individuals demonstrate a complex and severe clinical phenotype that has not been fully characterized to date. In this report, we describe two individuals with distinct clinical presentations of MSD. Also, we detail a comprehensive systems-based approach to the management of individuals with MSD, from the initial diagnostic evaluation to unique multisystem issues and potential management options. As there have been no natural history studies to date, the recommendations within this report are based on published studies and consensus opinion and underscore the need for future research on evidence-based outcomes to improve management of children with MSD.

Status dystonicus in childhood

PURPOSE OF REVIEW

Dystonia is a common paediatric neurological condition. At its most severe, dystonia may lead to life-threatening complications, a state termed status dystonicus. This review provides an update on the definition, causes, management and outcome of childhood status dystonicus.

RECENT FINDINGS

High-quality studies in childhood status dystonicus are lacking, though an increasing number of case series have been published. Status dystonicus appears to occur more frequently in children compared with adults, with a clear precipitant identified in around two-thirds of cases. Although febrile illness remains the commonest trigger for status dystonicus, unplanned interruption to deep brain stimulation (DBS) is increasingly reported as a precipitant. In parallel with this, neurosurgical intervention for status dystonicus appears to have become more widely used, though optimum timing and patient selection remains unclear. In most cases, a multistaged approach is required; we propose an 'ABCD' approach - Addressing precipitants, Beginning supportive measures, Calibrating sedation and Dystonia specific medications. Outcomes following status dystonicus appear to have slightly improved in recent years, potentially as a consequence of increasing use of DBS, though mortality has remained around 10%.

SUMMARY

Future work is needed to inform evidence-based guidelines for the management of status dystonicus. One of many pressing questions is the precise indication, and timing of interventions such as DBS.

Clinical Management of Dystonia in Childhood

Dystonia is one of the most frequent movement disorders in childhood. It can impede normal motor development and cause significant motor disability. The diagnostic evaluation of childhood dystonia is challenging due to the phenotypic variability and heterogeneous etiologies. Evidence to guide the diagnostic evaluation and treatment is limited. Assessment is primarily directed by clinical history and distinctive examination findings. Neuroimaging is typically necessary to evaluate for acquired or complex inherited dystonias. A trial of levodopa can be both diagnostic and therapeutic in children with dopa-responsive dystonia. However, for the majority of children with early-onset dystonia, treatment is symptomatic with varying efficacy. There is a paucity of therapeutic trials for childhood dystonia and most treatment recommendations are consensus or expert opinion driven. This review summarizes the available evidence and guidelines on the diagnostic evaluation and pharmacological treatment of childhood-onset dystonia and provides practical frameworks to approach both issues based on best evidence.

Revised consensus statement on the preventive and symptomatic care of patients with leukodystrophies

Leukodystrophies are a broad class of genetic disorders that result in disruption or destruction of central myelination. Although the mechanisms underlying these disorders are heterogeneous, there are many common symptoms that affect patients irrespective of the genetic diagnosis. The comfort and quality of life of these children is a primary goal that can complement efforts directed at curative therapies. Contained within this report is a systems-based approach to management of complications that result from leukodystrophies. We discuss the initial evaluation, identification of common medical issues, and management options to establish a comprehensive, standardized care approach. We will also address clinical topics relevant to select leukodystrophies, such as gallbladder pathology and adrenal insufficiency. The recommendations within this review rely on existing studies and consensus opinions and underscore the need for future research on evidence-based outcomes to better treat the manifestations of this unique set of genetic disorders.

Clonidine use in the outpatient management of severe secondary dystonia

OBJECTIVE

To evaluate the safety, efficacy and effective dosage of clonidine in the outpatient (OP) management of secondary dystonia.

METHODS

A retrospective analysis of children and young people (CAYP) prescribed clonidine in an OP clinic between January 2011 and November 2013 for dystonia management. Of 224 children receiving clonidine, 149/224 did not have a movement disorder and 12/224 had no data leaving 63 movement disorder cases, 15/63 managed as in-patients, 15/48 suffered from tics leaving 33/63 for OP evaluation. Clonidine effectiveness was assessed by 'yes/no' criteria in improving 5 areas: seating, sleep, pain, tone and involuntary movements.

RESULTS

2/33 motor cases had insufficient data; 7/33 had concurrent therapy leaving 24/33 for analysis. Improvement in at least one area was reported by 20/24 (83%) CAYP: Improved seating tolerance 14/24, and sleep 15/24; reduced pain 15/24; improved tone 16/24 and involuntary movements 17/24. Starting doses ranged from 1 mcg/kg OD to 2 mcg/kg TDS with optimum doses reached on average at 9.5 months follow-up. Maximum dose reached was 75 mcg/kg/day given in 8 divided doses. Average maximum daily dose was 20 mcg/kg/day. The commonest frequency of administration was 8 hourly. Side effects were reported in 11/24 CAYP and discontinued in 1/24 for lack of clinical effectiveness, 1/24 for side effects and 4/24 due to both lack of effectiveness and side effects.

CONCLUSION

Clonidine was effective in secondary dystonia management in 83% of cases. A starting dose of 1 mcg/kg TDS was well tolerated and safely escalated. Prospective objective evaluation is now required to confirm the efficacy of clonidine.

Hypertonia

Hypertonia is the abnormal increase in muscle tone as a result of upper motor neuron lesions. There are three following clinical types: spasticity, dystonia, and rigidity. Management of hypertonia is individualized and should be directed by the patient and/or family׳s goals of care as well as the underlying cause of the hypertonia. Treatment options include stretching, strengthening, positioning, oral medications, botulinum toxin injections, phenol injections, as well as surgical procedures. Without effective management, hypertonia can result in muscle imbalance, abnormal movement patterns, pain, joint contracture, joint deformity, and ultimately negatively impact a patient׳s function. This discussion serves as an overview of hypertonia, focusing on spasticity and dystonia, in the pediatric population by examining the causes and epidemiology, elucidating its symptoms, discussing available treatment and management options, and clarifying why this all matters.

Pain Assessment and Treatment in Children With Significant Impairment of the Central Nervous System

Pain is a frequent and significant problem for children with impairment of the central nervous system, with the highest frequency and severity occurring in children with the greatest impairment. Despite the significance of the problem, this population remains vulnerable to underrecognition and undertreatment of pain. Barriers to treatment may include uncertainty in identifying pain along with limited experience and fear with the use of medications for pain treatment. Behavioral pain-assessment tools are reviewed in this clinical report, along with other strategies for monitoring pain after an intervention. Sources of pain in this population include acute-onset pain attributable to tissue injury or inflammation resulting in nociceptive pain, with pain then expected to resolve after treatment directed at the source. Other sources can result in chronic intermittent pain that, for many, occurs on a weekly to daily basis, commonly attributed to gastroesophageal reflux, spasticity, and hip subluxation. Most challenging are pain sources attributable to the impaired central nervous system, requiring empirical medication trials directed at causes that cannot be identified by diagnostic tests, such as central neuropathic pain. Interventions reviewed include integrative therapies and medications, such as gabapentinoids, tricyclic antidepressants, α-agonists, and opioids. This clinical report aims to address, with evidence-based guidance, the inherent challenges with the goal to improve comfort throughout life in this vulnerable group of children.

A post hoc study on gene panel analysis for the diagnosis of dystonia

BACKGROUND

Genetic disorders causing dystonia show great heterogeneity. Recent studies have suggested that next-generation sequencing techniques such as gene panel analysis can be effective in diagnosing heterogeneous conditions. The objective of this study was to investigate whether dystonia patients with a suspected genetic cause could benefit from the use of gene panel analysis.

METHODS

In this post hoc study, we describe gene panel analysis results of 61 dystonia patients (mean age, 31 years; 72% young onset) in our tertiary referral center. The panel covered 94 dystonia-associated genes. As comparison with a historic cohort was not possible because of the rapidly growing list of dystonia genes, we compared the diagnostic workup with and without gene panel analysis in the same patients. The workup without gene panel analysis (control group) included theoretical diagnostic strategies formulated by independent experts in the field, based on detailed case descriptions. The primary outcome measure was diagnostic yield; secondary measures were cost and duration of diagnostic workup.

RESULTS

Workup with gene panel analysis led to a confirmed molecular diagnosis in 14.8%, versus 7.4% in the control group (P = 0.096). In the control group, on average 3 genes/case were requested. The mean costs were lower in the gene panel analysis group (€1822/case) than in the controls (€2660/case). The duration of the workup was considerably shorter with gene panel analysis (28 vs 102 days).

CONCLUSIONS

Gene panel analysis facilitates molecular diagnosis in complex cases of dystonia, with a good diagnostic yield (14.8%), a quicker diagnostic workup, and lower costs, representing a major improvement for patients and their families. © 2016 International Parkinson and Movement Disorder Society.

Complications of Deep Brain Stimulation (DBS) for dystonia in children - The challenges and 10 year experience in a large paediatric cohort

Deep brain stimulation (DBS) has been increasingly used for primary and secondary movement disorders in children and young people. Reports of hardware related complications have been sparse for this population and from small cohorts of patients. We report DBS complications from a single large DBS centre with 10 year experience. Data was collected as a prospective audit and additionally from a questionnaire on recharging of the stimulators. 129 patients with a minimum 6 months follow up were identified, mean age10.8 y (range 3.0-18.75), mean follow up 3.3y (range 0.5-10.3), weight 10.4-94.2 kg, 126 new implants (92 Activa RC) and 69 revisions for reasons other than infection. 26 patients were 7y or younger. Surgical site infections (SSI) rates were 10.3% for new implants and revisions, lower 8.6% for new Activa RC and even lower, 4.7%, for new Activa RC in patients under 7y (1/21). SSI occurred within first 6 months and necessitated total system removal in 86% of those infected. Electrode/extension problems were recorded in 18.4% of patients, fracture in 4.6% malfunction in 7.7%, short extension 3.8% and electrode migration in 2.3%. Other complications involved clinically silent intracranial bleed in 1 patient, skin erosions (2.3%), unexpected switching off in 18.7% of Soletra/Kinetra and 3.4% of Activa RC, transient seroma at IPG site in postoperative period (8%). Of the 48 returned recharging questionnaires, 38% of families required recharger replacement and 23% experienced frequent problems maintaining connection during recharging. However, 83% of responders considered recharging not at all or only a little care burden. We identified lower than previously reported DBS infection rates particularly for patients under 7 years, but relatively high incidence of technical problems with electrodes, extensions and in particular recharging. This has to be considered when offering DBS for children with movement disorders.

The International Classification of Functioning (ICF) to evaluate deep brain stimulation neuromodulation in childhood dystonia-hyperkinesia informs future clinical & research priorities in a multidisciplinary model of care

The multidisciplinary team (MDT) approach illustrates how motor classification systems, assessments and outcome measures currently available have been applied to a national cohort of children and young people with dystonia and other hyperkinetic movement disorders (HMD) particularly with a focus on dyskinetic cerebral palsy (CP). The paper is divided in 3 sections. Firstly, we describe the service model adopted by the Complex Motor Disorders Service (CMDS) at Evelina London Children's Hospital and King's College Hospital (ELCH-KCH) for deep brain stimulation. We describe lessons learnt from available dystonia studies and discuss/propose ways to measure DBS and other dystonia-related intervention outcomes. We aim to report on current available functional outcome measures as well as some impairment-based assessments that can encourage and generate discussion among movement disorders specialists of different backgrounds regarding choice of the most important areas to be measured after DBS and other interventions for dystonia management. Finally, some recommendations for multi-centre collaboration in regards to functional clinical outcomes and research methodologies for dystonia-related interventions are proposed.

Historical developments in children's deep brain stimulation

BACKGROUND

Heterogeneous by the underlying pathobiology and clinical presentation, childhood onset dystonia is most frequently progressive, with related disability and limitations in functions of daily living. Consequently, there is an obvious need for efficient symptomatic therapies.

METHODS AND RESULTS

Following lesional surgery to basal ganglia (BG) and thalamus, deep brain stimulation (DBS) is a more conservative and adjustable intervention to and validated for internal segment of the globus pallidus (GPi), highly efficient in treating isolated "primary" dystonia and associated symptoms such as subcortical myoclonus. The role of DBS in acquired, neurometabolic and degenerative disorders with dystonia deserves further exploration to confirm as an efficient and lasting therapy. However, the pathobiological background with distribution of the sequellae over the central nervous system and related clinical features, will limit DBS efficacy in these conditions. Cumulative arguments propose DBS in severe life threatening dystonic conditions called status dystonicus as first line therapy, irrespective of the underlying cause. There are no currently available validated selection criteria for DBS in pediatric dystonia. Concurrent targets such as subthalamic nucleus (STN) and several motor nuclei of the thalamus are under exploration and only little information is available in children. DBS programming in paediatric population was adopted from experience in adults. The choice of neuromodulatory DBS parameters could influence not only the initial therapeutic outcome of dystonic symptoms but also its maintenance over time and potentially the occurrence of DBS related side effects.

CONCLUSION

DBS allows efficient symptomatic treatment of severe dystonia in children and advances pathophysiological knowledge about local and distributed abnormal neural activity over the motor cortical-subcortical networks in dystonia and other movement disorders.

Recognizing the Common Origins of Dystonia and the Development of Human Movement: A Manifesto of Unmet Needs in Isolated Childhood Dystonias

Dystonia in childhood may be severely disabling and often unremitting and unrecognized. Considered a rare disorder, dystonic symptoms in childhood are pervasive in many conditions including disorders of developmental delay, cerebral palsy (CP), autism, neurometabolic, neuroinflammatory, and neurogenetic disorders. Collectively, there is a need to recognize the role of early postures and movements which characterize phases of normal fetal, infant, and child development as a backdrop to the many facets of dystonia in early childhood neurological disorders and to be aware of the developmental context of dystonic symptoms. The role of cocontraction is explored throughout infancy, childhood, young adulthood, and in the elderly. Under-recognition of pervasive dystonic disorders of childhood, including within CP is reviewed. Original descriptions of CP by Gowers are reviewed and contemporary physiological demonstrations are used to illustrate support for an interpretation of the tonic labyrinthine response as a manifestation of dystonia. Early recognition and molecular diagnosis of childhood dystonia where possible are desirable for appropriate clinical stratification and future precision medicine and functional neurosurgery where appropriate. A developmental neurobiological perspective could also be useful in exploring new clinical strategies for adult-onset dystonia disorders focusing on environmental and molecular interactions and systems behaviors.

Classification of dystonia in childhood

OBJECTIVE

The most recent international consensus update on dystonia classification proposed a system based on 2 axes, clinical characteristics and aetiology. We aimed to apply this system to Children and Young People (CAYP) selected for movement disorder surgery, and determine if meaningful groupings of cases could be extracted.

METHODS

The 2013 Consensus Committee classification system for dystonia was retrospectively applied to 145 CAYP with dystonic movement disorders. Two-step cluster analysis was applied to the resulting categorisations to identify groupings of CAYP with similar characteristics.

RESULTS

Classification resulted in a total of 43 unique groupings of categorisation. Cluster analysis detected 4 main clusters of CAYP, comparable to previously used patient groupings.

CONCLUSIONS

The 2013 consensus update on dystonia classification can be applied to CAYP with dystonia. The large number of categories provides a wealth of information for the clinician, and also facilitates data driven grouping into clinically meaningful subgroups.

Neurometabolic disorders are treatable causes of dystonia

A broad range of rare inherited metabolic disorders can present with dystonia. For clinicians, it is important to recognize dystonic features, but it can be complicated by the mixed and complex clinical picture seen in many neurometabolic patients. Careful phenotyping is the first step towards the diagnosis of the underlying condition and subsequent targeted treatment, further supported by imaging, biochemical diagnostics and the availability of modern diagnostic techniques such as next generation sequencing. As several neurometabolic disorders are treatable causes of dystonia, these should have priority in the diagnostic process. In the symptomatic treatment of dystonia, several therapeutic options are available. Awareness for the occurrence and optimal treatment of dystonia and other movement disorders in neurometabolic conditions is important because these symptoms can have a substantial impact on the quality of life and daily functioning; this effect is not only exerted by the dystonia itself, but also by the frequently associated non-motor features. In this paper, the highlights and key concepts of neurometabolic forms of dystonia are discussed, with a focus on phenomenology, the diagnostic approach, the most important neurometabolic aetiologies, co-occurring non-motor features and therapeutic options.

Rater reliability and scoring duration of the Quality Function Measure in ambulant children with hyperkinetic movement disorders

AIM

To examine intra- and interrater reliability/agreement, and time taken to score, when the Quality Function Measure (QFM) is applied to children with hyperkinetic movement disorders (HMD; e.g. dystonia, chorea, athetosis, tremor, and myoclonus).

METHOD

Fifteen ambulant children with HMD participated (eight males, seven females; mean age 13y 7mo, SD 3y 7mo). Three trained raters (two physiotherapists, one occupational therapist) independently scored the QFM using videos of each child performing Gross Motor Function Measure (GMFM) Stand and Walk/Run/Jump dimensions. Reliability was evaluated using intraclass correlation coefficient (ICC) model 2.1, Standard Error of Measurement (SEM), and Bland-Altman methods.

RESULTS

Rater reliability was excellent for all five QFM attributes: intrarater ICCs ≥0.98 (95% confidence interval [CI] 0.83-1.00), and interrater ICCs ≥0.96 (95% CI 0.91-1.00). SEM varied from 2.07% to 4.72% points for intra- and interrater scores across QFM attributes. Bland-Altman tests demonstrated close agreement between ratings, with absolute mean differences varying from 0.34% to 3.23% (intrarater) to 1.67% to 3.82% (interrater). Median scoring duration time was 83 minutes (range 56-144min, SD 16.02).

INTERPRETATION

Low measurement error attributable to rater effects suggests the QFM has potential as an evaluative measure in research studies involving children with HMD, though its lengthy scoring requirements are an important consideration for clinical practice. Evaluation of test-retest reliability and responsiveness is required.

Tensor and non-tensor tractography for the assessment of the corticospinal tract of children with motor disorders: a comparative study

INTRODUCTION

Non-invasive measures of corticospinal tract (CST) integrity may help to guide clinical interventions, particularly in children and young people (CAYP) with motor disorders. We compared diffusion tensor imaging (DTI) metrics extracted from the CST generated by tensor and non-tensor based tractography algorithms.

METHODS

For a group of 25 CAYP undergoing clinical evaluation, the CST was reconstructed using (1) deterministic tensor-based tractography algorithm, (2) probabilistic tensor-based, and (3) constrained spherical deconvolution (CSD)-derived tractography algorithms.

RESULTS

Choice of tractography algorithm significantly altered the results of tracking. Larger tracts were consistently defined with CSD, with differences in FA but not MD values for tracts to the pre- or post-central gyrus. Differences between deterministic and probabilistic tensor-based algorithms were minimal. Non-tensor reconstructed tracts appeared to be more anatomically representative. Examining metrics along the tract, difference in FA values appeared to be greatest in voxels with predominantly single-fibre orientations. Less pronounced differences were seen outwith of these regions.

CONCLUSION

With an increasing interest in the applications of tractography analysis at all stages of movement disorder surgery, it is important that clinicians remain alert to the consequences of choice of tractography algorithm on subsequently generated tracts, including differences in volumes, anatomical reconstruction, and DTI metrics, the latter of which will have global as well as more regional effects. Tract-wide analysis of DTI based metrics is of limited utility, and a more segmental approach to analysis may be appropriate, particularly if disruption to a focal region of a white matter pathway is anticipated.

Medication use in childhood dystonia

BACKGROUND

Data around current prescription practices in childhood dystonia is limited. Medication use may be limited by side effects, the incidence of which is uncertain. For a large cohort assessed by our supra-regional service we aimed to: i) Review medications used at the point of referral. ii) Determine the prevalence of adverse drug responses (ADR) resulting in discontinuation of drug use. iii) Identify clinical risk factors for ADR.

METHODS

Case note review of 278 children with dystonia referred to our service. Data collected on medications, ADR, dystonia aetiology, Gross Motor Function Classification System (GMFCS) level and motor phenotype (pure dystonia/mixed dystonia-spasticity). Logistic regression analysis was used to identify risk factors for ADR.

RESULTS

At referral 82/278 (29.4%) children were taking no anti-dystonic medication. In the remainder the median number of anti-dystonic medications was 2 (range 1-5). Medications use increased with worsening GMFCS level. The commonest drugs used were baclofen (118/278: 42.4%), trihexyphenidyl (98/278: 35.2%), l-Dopa (57/278: 20.5%) and diazepam (53/278: 19%). Choice of medication appeared to be influenced by dystonia aetiology. ADR had been experienced by 171/278 (61.5%) of children. The commonest drugs responsible for ADR were trihexyphenidyl (90/171: 52.3%), baclofen (43/171: 25.1%) and l-Dopa (26/171: 15.2%). Binary logistic regression demonstrated no clinical risk factors for ADR.

CONCLUSIONS

ADR is commonly experienced by children with dystonia, regardless of dystonia severity or aetiology. A wide variation in drug management of dystonia was identified. Collectively these findings highlight the need for a rational approach to the pharmacological management of dystonia in childhood.

Advances in management of movement disorders in children

Movement disorders in children are causally and clinically heterogeneous and present in a challenging developmental context. Treatment options are broad ranging, from pharmacotherapy to invasive neuromodulation and experimental gene and stem cell therapies. The clinical effects of these therapies are variable and often poorly sustained, and only a few of the management strategies used in paediatric populations have been tested in randomised controlled studies with age-appropriate cohorts. Identification of the most appropriate treatment is uniquely challenging in children because of the incomplete knowledge about the pathophysiology of movement disorders and their influence on normal motor development; thus, effective therapeutic options for these children remain an unmet need. It is vital to transfer the expanding knowledge of the movement disorders into the development of novel symptomatic or, ideally, disease-modifying treatments, and to assess these therapeutic strategies in appropriately designed and well done trials.

The Burke-Fahn-Marsden Dystonia Rating Scale is Age-Dependent in Healthy Children

Background

The Burke-Fahn-Marsden Dystonia Rating Scale is a universally applied instrument for the quantitative assessment of dystonia in both children and adults. However, immature movements by healthy young children may also show "dystonic characteristics" as a consequence of physiologically incomplete brain maturation. This could implicate that Burke-Fahn-Marsden scale scores are confounded by pediatric age.

Objective

In healthy young children, we aimed to determine whether physiologically immature movements and postures can induce an age-related effect on Burke-Fahn-Marsden movement and disability scale scores.

Methods

Nine assessors specializied in movement disorders (3 adult neurologists, 3 pediatric neurologists, and 3 MD/PhD students) independently scored the Burke-Fahn-Marsden movement scale in 52 healthy children (4-16 years of age; 2 boys and 2 girls per year of age). Independent of that, parents scored their children's functional motor development according to the Burke-Fahn-Marsden disability scale in another 52 healthy children (4-16 years of age; 2 boys and 2 girls per year of age). By regression analysis, we determined the association between Burke-Fahn-Marsden movement and disability scales outcomes and pediatric age.

Results

In healthy children, assessment of physiologically immature motor performances by the Burke-Fahn-Marsden movement and disability scales showed an association between the outcomes of both scales and age (until 16 years and 12 years of age, β = -0.72 and β = -0.60, for Burke-Fahn-Marsden movement and disability scale, respectively [both P < 0.001]).

Conclusions

The Burke-Fahn-Marsden movement and disability scales are influenced by the age of the child. For accurate interpretation of longitudinal Burke-Fahn-Marsden Dystonia Rating Scale scores in young dystonic children, consideration of pediatric age-relatedness appears advisory.

Burke-Fahn-Marsden dystonia severity, Gross Motor, Manual Ability, and Communication Function Classification scales in childhood hyperkinetic movement disorders including cerebral palsy: a 'Rosetta Stone' study

AIM

Hyperkinetic movement disorders (HMDs) can be assessed using impairment-based scales or functional classifications. The Burke-Fahn-Marsden Dystonia Rating Scale-movement (BFM-M) evaluates dystonia impairment, but may not reflect functional ability. The Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS), and Communication Function Classification System (CFCS) are widely used in the literature on cerebral palsy to classify functional ability, but not in childhood movement disorders. We explore the concordance of these three functional scales in a large sample of paediatric HMDs and the impact of dystonia severity on these scales.

METHOD

Children with HMDs (n=161; median age 10y 3mo, range 2y 6mo-21y) were assessed using the BFM-M, GMFCS, MACS, and CFCS from 2007 to 2013. This cross-sectional study contrasts the information provided by these scales.

RESULTS

All four scales were strongly associated (all Spearman's rank correlation coefficient rs >0.72, p<0.001), with worse dystonia severity implying worse function. Secondary dystonias had worse dystonia and less function than primary dystonias (p<0.001). A longer proportion of life lived with dystonia is associated with more severe dystonia (rs =0.42, p<0.001).

INTERPRETATION

The BFM-M is strongly linked with the GMFCS, MACS, and CFCS, irrespective of aetiology. Each scale offers interrelated but complementary information and is applicable to all aetiologies. Movement disorders including cerebral palsy can be effectively evaluated using these scales.

Cerebral palsy

Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging.

Fractional anisotropy in children with dystonia or spasticity correlates with the selection for DBS or ITB movement disorder surgery

INTRODUCTION

There is increasing interest in neurosurgical interventions for hypertonicity in children and young people (CAYP), which often presents with a mixture of dystonia and spasticity. Significant spasticity would usually be considered a contraindication for deep brain stimulation (DBS) and more suitably treated with intrathecal baclofen (ITB). We aimed to explore whether white matter microstructure, as measured by Fractional Anisotropy (FA), differed between CAYP selected for DBS compared to ITB surgery.

METHODS

We retrospectively analysed Diffusion Tensor Imaging for 31 CAYP selected for DBS surgery (14 primary dystonia, 17 secondary dystonia) and 10 CAYP selected for ITB surgery. A voxel-wise comparison of FA values was performed using tract-based spatial statistics, comparing primary and secondary dystonia groups to the ITB group, and the two dystonia groups.

RESULTS

Widespread areas of reduced FA were demonstrated in ITB compared to either DBS group and in CAYP with secondary compared to primary dystonia. These changes were not restricted to motor pathways. Region of interest (ROI) analysis from the corticospinal tract (CST) demonstrated groupwise differences but overlapping values at the individual level.

CONCLUSIONS

DTI measures may contribute to decision making for CAYP selection for movement disorder surgery. Significant differences in CAYP with secondary dystonia selected for DBS surgery compared to CAYP selected for ITB pump implants, suggesting that more extensive white matter injury may be a feature of the spastic motor phenotype. Altered white matter microstructure could potentially explain the reduced responsiveness to interventions such as DBS in secondary compared to primary dystonia.

Dystonia in children and adolescents: a systematic review and a new diagnostic algorithm

Early aetiological diagnosis is of paramount importance for childhood dystonia because some of the possible underlying conditions are treatable. Numerous genetic and non-genetic causes have been reported, and diagnostic workup is often challenging, time consuming and costly. Recently, a paradigm shift has occurred in molecular genetic diagnostics, with next-generation sequencing techniques now allowing us to analyse hundreds of genes simultaneously. To ensure that patients benefit from these new techniques, adaptation of current diagnostic strategies is needed. On the basis of a systematic literature review of dystonia with onset in childhood or adolescence, we propose a novel diagnostic strategy with the aim of helping clinicians determine which patients may benefit by applying these new genetic techniques and which patients first require other investigations. We also provide an up-to-date list of candidate genes for a dystonia gene panel, based on a detailed literature search up to 20 October 2014. While new genetic techniques are certainly not a panacea, possible advantages of our proposed strategy include earlier diagnosis and avoidance of unnecessary investigations. It will therefore shorten the time of uncertainty for patients and their families awaiting a definite diagnosis.

Childhood dystonias

OPINION STATEMENT

Dystonia is a movement disorder caused by diverse etiologies. Its treatment in children is particularly challenging due to the complexity of the development of the nervous system from birth to young adulthood. The treatment options of childhood dystonia include several oral pharmaceutical agents, botulinum toxin injections, and deep brain stimulation (DBS) therapy. The choice of drug therapy relies on the suspected etiology of the dystonia and the adverse effect profile of the drugs. Dystonic syndromes with known etiologies may require specific interventions, but most dystonias are treated by trying serially a handful of medications starting with those with the best risk/benefit profile. In conjunction to drug therapy, botulinum toxin injections may be used to target a problematic group dystonic muscles. The maximal botulinum toxin dose is limited by the weight of the child, therefore limiting the number of the muscles amenable to such treatment. When drugs and botulinum toxin injections fail to control the child's disabling dystonia, DBS therapy may be offered as a last remedy. Delivering optimal DBS therapy to children with dystonia requires a multidisciplinary team of experienced pediatric neurosurgeons, neurologists, and nurses to select adequate candidates, perform this delicate stereotactic procedure, and optimize DBS delivery. Even in the best hands, the response of childhood dystonia to DBS therapy varies greatly. Future therapy of childhood dystonia will parallel the advancement of knowledge of the pathophysiology of dystonic syndromes and the development of clinical and research tools for their study.

The impact and prognosis for dystonia in childhood including dystonic cerebral palsy: a clinical and demographic tertiary cohort study

INTRODUCTION AND METHODS

The impact of dystonia in childhood is poorly understood. We report our experience of referrals between 2005 and 2012.

RESULTS

Of 294/315 assessable children, 15/294 had pure spasticity, leaving 279/294 with dystonia classified as primary (30/279:10.7%); primary-plus (19/279:6.8%) and secondary (230/279:82.4%) dystonia, including heredodegenerative dystonia (29/279:10.3%); 150/279 (53.7%) with cerebral palsy and 51/279 (18.2%) acquired brain injury. Definitive diagnoses were available in 222/294 (79.6%), but lower in primary/primary-plus compared with secondary groups (11/49 vs 211/230: Fisher's exact test p<0.0001). Spasticity comorbidity was present in 79/230 (34.3%) children. Median age (interquartile years) at referral was 9.75 (6.58-13), not significantly differing by aetiology (Kruskal-Wallis test p>0.05); dystonia-onset age was 3 (0.5-7.0) for primary/primary-plus and 0.25 (0.08-0.8) in the secondary/CP groups. Dystonia duration at referral was 4.75 years (3.0-10.33) for primary/primary-plus groups and 7.83 (5.4-11) in the secondary group. The mean (interquartile range) proportion of life lived with dystonia, derived as dystonia duration normalised to age was 0.68 (0.31-0.96); 0.59 (0.35-0.8); 0.75 (0.62-0.95)and 0.9 (0.92-0.99) for primary, primary-plus, heredodegenerative and secondary-static dystonias respectively. Only 91/279 (32.6%) experienced a period of normal motor development. Carers perceived dystonia deterioration in 168/279 (60.2%), stabilisation in 88/279 (31.5%) and improvement in 23/279 (8.2%). Dystonia occurred in 26/225 (11.6%) siblings: 14/26 secondary and 5/26 heredodegenerative dystonia. Comorbidities were identified in 176/279 (63.1%) cases. Gross Motor Function Classification System (GMFCS) levels I-III were commoner in primary/primary-plus (37/49: 75%) compared with secondary/CP (29/230:13%) cases, χ(2) p<0.0001).

DISCUSSION

In this selective cohort, childhood dystonia is severe, presenting early before worsening without remission. Secondary dystonias spend a higher proportion of life living with dystonia and lower functional capacity. Despite referral bias, services offering neurosurgical interventions and health service planning agencies should understand the context and predicament of life with childhood dystonia.