Dystonien im Kindesalter

Childhood dystonias represent a heterogeneous group of mostly inherited disorders. In this age group, generalized dystonias predominate and cause significant disability. A functional disturbance in the striatal control of the internal globus pallidus causing altered thalamic control of cortical motor areas seems to represent the pathophysiological background. We discuss the etiologic differentiation of primary dystonias from acquired/exogenous causes and heredodegenerative disorders. With the exception of dopa-responsive dystonia, treatment of dystonia is difficult. Besides medical therapy, neurosurgical procedures like bilateral pallidal stimulation show significant clinical benefit in special etiologic groups of dystonia, i.e., primary generalized dystonia.     

Diagnosis and treatment of pediatric onset isolated dystonia

Isolated dystonia refers to a genetic heterogeneous group of progressive conditions with onset of symptoms during childhood or adolescence, progressive course with frequent generalization and marked functional impairment. There are well-known monogenic forms of isolated dystonia with pediatric onset such as DYT1 and DYT6 transmitted with autosomal dominant inheritance and low penetrance. Genetic findings of the past years have widened the etiological spectrum and the phenotype. The recently discovered genes (GNAL, ANO-3, KTM2B) or variant of already known diseases, such as Ataxia-Teleangectasia, are emerging as another causes of pediatric onset dystonia, sometimes with a more complex phenotype, but their incidence is unknown and still a considerable number of cases remains genetically undetermined.Due to the severe disability of pediatric onset dystonia treatment remains unsatisfactory and still mainly based upon oral pharmacological agents. However, deep brain stimulation is now extensively applied with good to excellent results especially when patients are treated early during the course of the disease.     

Early onset primary dystonia

Dystonia is a syndrome characterized by sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. It is classified by age at onset, by distribution, and by aetiology. The aetiological classification distinguishes the following categories: primary, dystonia plus, secondary, heredo-degenerative and psychogenic dystonia.Primary dystonia is defined as clinical condition characterized by dystonia as the only neurological abnormality apart from tremor. Different genetic alterations and gene loci have been mapped in familial and sporadic patients. Early onset-primary dystonia (EO-PD) is the most severe form of primary dystonia, with clinical and genetic heterogeneity. It usually starts in one body part, subsequently spreads to involve other body regions with frequent generalization. DYT1 dystonia is transmitted as an autosomal dominant trait with reduced penetrance. The unique underlying mutation is a GAG deletion in the coding region of the TOR1A gene, located at chromosome 9q34. DYT16 dystonia is a novel recessive form of EO-PD, recently described in few patients, caused by mutations in the PRKRA gene located at chromosome 2q31. At least other two loci have been mapped, but there remains a large number of patients with EO-PD in whom no genetic alteration is discovered.     

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

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

Review of the phenotype of early-onset generalised progressive dystonia due to mutations in KMT2B

In 2016, two research groups independently identified microdeletions and pathogenic variants in the lysine-specific histone methyltransferase 2B gene, KMT2B in patients with early-onset progressive dystonia. KMT2B-dystonia (DYT28) is emerging as an important and frequent cause of childhood-onset progressive generalised dystonia and is estimated to potentially account for up to 10% of early-onset generalised dystonia. Herein, we review variants in KMT2B associated with dystonia, as well as the clinical phenotype, treatment and underlying disease mechanisms. Furthermore, in context of this newly identified condition, we summarise our approach to the genetic investigation of paediatric dystonia.     

Beyond the Burke-Fahn-Marsden Dystonia Rating Scale: deep brain stimulation in childhood secondary dystonia

PurposeDeep brain stimulation is now widely accepted as an effective treatment for children with primary generalized dystonia. More variable results are reported in secondary dystonias and its efficacy in this heterogeneous group has not been fully elucidated. Deep brain stimulation outcomes are typically reported using impairment-focused measures, such as the Burke–Fahn–Marsden Dystonia Rating Scale, which provide little information about function and participation outcomes or changes in non-motor areas.The aim is to demonstrate that in some cases of secondary dystonia, the sole use of impairment level measures, such as the Burke–Fahn–Marsden Dystonia Rating Scale, may be insufficient to fully evaluate outcome following deep brain stimulation.MethodsSix paediatric cases who underwent deep brain stimulation surgery with a minimum of one year follow up were selected on the basis of apparent non-response to deep brain stimulation, defined as a clinically insignificant change in the Burke–Fahn–Marsden Dystonia Movement Scale (<20%), but where other evaluation measures demonstrated clinical efficacy across several domains.ResultsDespite no significant change in Burke–Fahn–Marsden Dystonia Rating Scale scores following deep brain stimulation, parallel outcome measures demonstrated significant benefit in a range of child and family-centred goal areas including: pain and comfort, school attendance, seating tolerance, access to assistive technology and in some cases carer burden.ConclusionsSole use of impairment-focused measures, are limited in scope to evaluate outcome following deep brain stimulation, particularly in secondary dystonias. Systematic study of effects across multiple dimensions of disability is needed to determine what deep brain stimulation offers patients in terms of function, participation, care, comfort and quality of life. Deep brain stimulation may offer meaningful change across multiple domains of functioning, disability and health even in the absence of significant change in dystonia rating scales.     

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.

Polymyography in the diagnosis of childhood onset movement disorders

We report on the results of a clinical and polymyographic retrospective study of 61 paediatric patients with tremor, dystonia and/or myoclonus. Aim of the study was to verify the contribution of polymyography in the classification of these movement disorders and in their aetiological definition.

Methods

The movement disorders were clinically classified by two experts, based on clinical and videotape recordings evaluation; all patients underwent standardized polymyographic evaluation; aetiological diagnosis was performed according to diagnostic protocols for dystonia, myoclonus, tremor and psychogenic movement disorders. The polymyographic features were summarized in five different patterns (dystonia, subcortical myoclonus, myoclonic dystonia, tremor, normal) and compared with the clinical classification and with aetiological diagnosis.

Results

In more than 70% of the patients the polymyographic features were in accordance with the clinical classification; in 31% the polymyographic features allowed to identify a clinically unclassified movement disorder and in 19.6% disclosed a not clinically evident associated movement disorder. The polymyographic study did not contribute to the aetiological diagnosis, but was useful in supporting the clinical diagnosis of psychogenic movement disorder.     

Movement disorders in neuro-metabolic diseases

Inborn errors of metabolism (IEM) are a group of genetic disorders characterized by dysfunction of an enzyme or other protein involved in cellular metabolism.¹ Most IEMs involve the nervous system (neuro-metabolic diseases or NMD). NMD often present with a complex clinical picture: psychomotor retardation and/or regression, pyramidal signs, ataxia, hypotonia and epilepsy and movement disorders.¹ Movement disorders are more frequently part of this complex picture than a predominant symptom, however in some instances the clinical picture may be summarized in an invalidating movement disorder.²On a phenomenology basis, one can distinguish eight main types of movement disorders: dystonia and athetosis, chorea, tremor with or without parkinsonism, ballismus, myoclonus, tics and stereotypies. Most of these abnormal involuntary movements generate from a dysfunction or a lesion in the basal ganglia, excepting myoclonus, the origin of which can vary (cortical, brainstem, basal ganglia, spinal and even peripheral nervous system).³Classically the most frequently observed movement disorders in NMD are: dystonia, myoclonus, chorea, tremor and parkinsonism (Fig. 1). The primary goal of this article is, departing from the literature and a large personal series, to describe the types of movement disorders most frequently observed in NMD and to discuss their clinical value in the setting of specific types of NMD.     

Improvement in upper limb function in children with dystonia following deep brain stimulation

BackgroundChildhood dystonia can severely impact upper limb function. Deep Brain Stimulation (DBS) has been shown to be effective in reducing dystonic symptoms in childhood. Functional recovery following DBS is however not well understood.AimsTo explore changes in upper limb function following DBS in paediatric dystonia.MethodsUpper limb outcomes, using the Melbourne Assessment of Unilateral Upper Limb Function, are reported in 20 cases of childhood dystonia (unilateral n = 1, four limb n = 19) at 6 and 12 months following DBS.ResultsImprovement in at least in one upper limb was seen in the majority of cases (n = 17, 85%) at 12 months following DBS. Deterioration of scores in both upper limbs was seen in 3 children with progressive disorders. Grouping the children aetiologically, a significant improvement in the dominant hand was obtained for the primary dystonia/dystonia-plus group at both six (p = 0.018) and twelve months (p = 0.012). In secondary dystonia due to a static disorder, improvement was also seen at 6 (p = 0.043) and 12 months (p = 0.046) in the non-dominant hand. No significant change was found in the group of children with progressive disorders.ConclusionsDBS has the potential to alter upper limb function in children with primary and secondary dystonia. The dominant hand improved most in children with primary dystonias, with greater improvement in the non-dominant hand in secondary-static cases.     

Evaluation of functional goal outcomes using the Canadian Occupational Performance Measure (COPM) following Deep Brain Stimulation (DBS) in childhood dystonia

PurposeTo evaluate the functional goal-directed outcomes of Deep Brain Stimulation (DBS) in childhood dystonia according to aetiology and to explore relationship with a traditional impairment-based measure.MethodThis is a prospective case series study involving thirty children with dystonia with a 1-year follow-up post-DBS. The Canadian Occupational Performance Measure (COPM) and Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) were used as primary outcome measures. Results were analysed based on aetiology in 3 groups: 1. primary/primary plus dystonia; 2. secondary dystonia–cerebral palsy (CP); 3. secondary dystonia–non-CP group. Correlation between functional outcome using COPM and dystonia improvement as captured by BFMDRS was measured.ResultsAll groups demonstrated significant improvement in individualised goal attainment, measured with the COPM, at 1-year post-DBS. The secondary dystonia-CP group also achieved significant improvement at 6 months for performance and satisfaction scores. In the majority of secondary dystonias, the BFMDRS failed to demonstrate significant improvement. A linear correlation between change in BFMDRS and COPM scores was observed when the entire cohort was analysed.Interpretation/conclusionsDBS improved functional performance, independently of the dystonic phenotype. Improvements in individualized COPM functional goal areas were seen in the absence of significant changes in BFMDRS scores, highlighting the relative insensitivity of impairment scales in this patient group.     

脑深部电刺激治疗儿童肌张力障碍

目的:总结脑深部电刺激(DBS)对肌张力障碍的治疗效果。方法:收集2017年4月至2020年7月北京大学第一医院收治的肌张力障碍患儿的临床资料和外周血DNA,完善患儿DBS术前及术后肌张力障碍评分量表运动评分,完善全外显子测序检测。结果:共收集32例运用DBS治疗的肌张力障碍患儿。其中男16例,女16例;12例采用苍白...     

Movement disorders in children: Recent advances in management

In recent years there has been a growing interest towards pediatric movement disorders (PMD). The data derived from the synthesis of clinical observation, neuroimaging, biochemical and, molecular genetics studies have allowed for the identification of a significant number of pediatric diseases featuring movement disorders. The purpose of this review is to outline an approach to the advances in management of dystonia, neurotransmitter disorders, tics, and paroxysmal dyskinetic syndromes starting in children younger than 18 yr of age.     

Outcome measures for children with movement disorders

The huge contribution of advances in the pediatric neurosciences, improvements in clinical practice, and new therapeutic options, has led to the development of new models of treatment and rehabilitation for dystonia in the last decade. It is now generally agreed that a multidimensional therapeutic approach is needed for children with motor disorders, whose motor function-conceived as a complex perceptive, motor and cognitive process - is impaired at a crucial time in their development, with a fall out on how their various adaptive functions evolve. Neurophysiological studies, modern neuroimaging techniques, and advances in cognitive psychology have all contributed to improving our understanding of the potential effects of treatments in early age - not only on the symptoms, but also on plasticity processes and neuronal reorganization. The International Classification of Functioning, Disability and Health (ICF) promoted by the WHO, and the diffusion of family-centered models of healthcare have underscored the importance of the ecological perspective with a view to providing effective therapies and a satisfactory quality of life for dystonic children and their families.The advances made in this area have made it necessary to study and develope more appropriate treatment outcome measures.In the light of these aspects, there is still not enough literature on the generally-accepted, exhaustive dystonia assessment tools. Given these limits, it might be useful to discuss the strengths and weaknesses of the main tools currently used in this setting.     

Paroxysmal non-epileptic events

OBJECTIVE: This article aims at reviewing one of the most important problems faced by pediatricians in the field of child neurology. The paroxystic non-epileptic events are also a frequent reason for pediatric neurology consultations and admission for diagnostic videoelectroencephalogram monitoring. SOURCES: Literature review on the subject was perform on Medline, data were also collected from the main Pediatric Neurology Textbooks, which were found to be an important and unique source of information on the subject. SUMMARY OF THE FINDINGS: Many of the entities discussed in this paper are very common in the pediatric population such as syncope, breath-holding spells and the movement disorders associated with gastroesophageal reflux. Other syndromes are less frequent such as the paroxysmal dystonias and the Segawa Syndrome (dystonia with diurnal variation). CONCLUSIONS: The basic knowledge of these syndromes is very important since it may avoid unnecessary procedures and the wrongful diagnosis of epilepsy. Patients who are mistakenly diagnosed as epileptics are exposed to anticonvulsant medications, which are probably not going to be effective and may expose them to the risk of side effects.     

Stable cognitive functioning with improved perceptual reasoning in children with dyskinetic cerebral palsy and other secondary dystonias after deep brain stimulation

Background

Dystonia is characterised by involuntary movements (twisting, writhing and jerking) and postures. Secondary dystonias are described as a heterogeneous group of disorders with both exogenous and endogenous causes. There is a growing body of literature on the effects of deep brain stimulation (DBS) surgery on the motor function in childhood secondary dystonias, however research on cognitive function after DBS is scarce.

Mitochondrial disease: a practical approach for primary care physicians

Notorious variability in the presentation of mitochondrial disease in the infant and young child complicates its clinical diagnosis. Mitochondrial disease is not a single entity but, rather, a heterogeneous group of disorders characterized by impaired energy production due to genetically based oxidative phosphorylation dysfunction. Together, these disorders constitute the most common neurometabolic disease of childhood with an estimated minimal risk of developing mitochondrial disease of 1 in 5000. Diagnostic difficulty results from not only the variable and often nonspecific presentation of these disorders but also from the absence of a reliable biomarker specific for the screening or diagnosis of mitochondrial disease. A simplified and standardized approach to facilitate the clinical recognition of mitochondrial disease by primary physicians is needed. With this article we aimed to improve the clinical recognition of mitochondrial disease by primary care providers and empower the generalist to initiate appropriate baseline diagnostic testing before determining the need for specialist referral. This is particularly important in light of the international shortage of metabolism specialists to comprehensively evaluate this large and complex disease population. It is hoped that greater familiarity among primary care physicians with the protean manifestations of mitochondrial disease will facilitate the proper diagnosis and management of this growing cohort of pediatric patients who present across all specialties.     

Restrictive dermopathy—a lethal congenital laminopathy. Case report and review of the literature

Restrictive dermopathy (RD) is a rare, fatal, and genetically heterogeneous laminopathy with a predominant autosomal recessive heredity pattern. The phenotype can be caused by mutations in either LMNA (primary laminopathy) or ZMPSTE24 (secondary laminopathy) genes but mostly by homozygous or compound heterozygous ZMPSTE24 mutations. Clinicopathologic findings are unique, allowing a specific diagnosis in most cases. We describe a premature newborn girl of non-consanguineous parents who presented a rigid, translucent and tightly adherent skin, dysmorphic facies, multiple joint contractures and radiological abnormalities. The overall clinical, radiological, histological, and ultrastructural features were typical of restrictive dermopathy. Molecular genetic analysis revealed a homozygous ZMPSTE24 mutation (c.1085_1086insT). Parents and sister were heterozygous asymptomatic carriers. We conclude that RD is a relatively easy and consistent clinical and pathological diagnosis. Despite recent advances in our understanding of RD, the pathogenetic mechanisms of the disease are not entirely clarified. Recognition of RD and molecular genetic diagnosis are important to define the prognosis of an affected child and for recommending genetic counseling to affected families. However, the outcome for a live born patient in the neonatal period is always fatal.     

Recent advances in chromosome breakage syndromes and their diagnosis

Chromosome instability is a characteristic cytogenetic feature of a number of genetically determined disorders collectively called as the chromosome breakage syndromes or DNA-repair disorders. They are characterized by susceptibility to chromosomal breakages, increased frequency of breaks and interchanges occurring either spontaneously or following exposure to various DNA-damaging agents. These diseases are a group of genetic disorders sharing a number of features. They are all autosomal recessive, show an increased tendency for chromosomal aberrations and to develop malignancies. The principal diseases in this group having a diverse etiology and clinical manifestations include Fanconi anemia (FA), ataxia telangiectasia (AT), Nijmegen breakage syndrome (NBS), Bloom syndrome (BS), xeroderma pigementosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD). The underlying defect in these syndromes is the inability to repair a particular type of DNA damage. A number of repair disorder phenotypes are caused by more than one gene. The diagnosis of these syndromes is made by the characteristic clinical features specific to each disease, but the definitive diagnosis is achieved by laboratory investigations such as cytogenetic, biochemical and molecular methods. The importance of prenatal diagnosis and our experience are discussed in this article.