Pearls & Oy-sters: AARS2 Leukodystrophy-Tremor and Tribulations

A 35-year-old woman with a progressive, bilateral upper limb tremor, personality change, behavioral disturbance, and primary ovarian insufficiency was found to have AARS2-related leukodystrophy. She had congenital nystagmus which evolved to head titubation by age 8 years and then developed an upper limb tremor in her mid-teens. These symptoms stabilized during her 20s, but soon after this presentation at age 35 years, neurologic and behavioral disturbances progressed rapidly over a 12-month period requiring transition to an assisted living facility with care support (4 visits/day) and assistance for all activities of daily living. MRI of the brain demonstrated confluent white matter changes predominantly involving the frontal lobes consistent with a leukodystrophy. All other investigations were unremarkable. Nongenetic causes of a leukodystrophy including sexually transmitted diseases and recreational drug use were excluded. Family history was negative for similar symptoms. Gene panel testing identified compound heterozygous pathogenic AARS2 mutations. This case highlights the importance of MRI brain imaging in progressive tremor syndromes, the utility of gene panels in simultaneous testing of multiple disorders with overlapping phenotypes, and the need for awareness of comorbid endocrinological disorders in many of the genetic leukodystrophies, whose identification may aid in clinical diagnosis.

Prevalence and temporal relationship of clinical co-morbidities in idiopathic dystonia: a UK linkage-based study

While motor and psychiatric phenotypes in idiopathic dystonia are increasingly well understood, a few studies have examined the rate, type, and temporal pattern of other clinical co-morbidities in dystonia. Here, we determine the rates of clinical diagnoses across 13 broad systems-based diagnostic groups, comparing an overall idiopathic dystonia cohort, and sub-cohorts of cervical dystonia, blepharospasm, and dystonic tremor, to a matched-control cohort. Using the SAIL databank, we undertook a longitudinal population-based cohort study (January 1st 1994-December 31st 2017) using anonymised electronic healthcare records for individuals living in Wales (UK), identifying those diagnosed with dystonia through use of a previously validated algorithm. Clinical co-morbid diagnoses were identified from primary health care records, with a 10% prevalence threshold required for onward analysis. Using this approach, 54,166 dystonia cases were identified together with 216,574 matched controls. Within this cohort, ten of the main ICD-10 diagnostic codes exceeded the 10% prevalence threshold over the 20-year period (infection, neurological, respiratory, gastrointestinal, genitourinary, dermatological, musculoskeletal, circulatory, neoplastic, and endocrinological). In the overall dystonia cohort, musculoskeletal (aOR: 1.89, aHR: 1.74), respiratory (aOR: 1.84; aHR: 1.65), and gastrointestinal (aOR: 1.72; aHR: 1.6) disorders had the strongest associations both pre- and post-dystonia diagnosis. However, variation in the rate of association of individual clinical co-morbidities was observed across the cervical, blepharospasm, and tremor dystonia groups. This study suggests an increased rate of specific co-morbid clinical disorders both pre- and post-dystonia diagnosis which should be considered during clinical assessment of those with dystonia to enable optimum symptomatic management.

Macro- and micro-structural insights into primary dystonia: a UK Biobank study

BACKGROUND

Dystonia is a hyperkinetic movement disorder with key motor network dysfunction implicated in pathophysiology. The UK Biobank encompasses > 500,000 participants, of whom 42,565 underwent brain MRI scanning. This study applied an optimized pre-processing pipeline, aimed at better accounting for artifact and improving data reliability, to assess for grey and white matter structural MRI changes between individuals diagnosed with primary dystonia and an unaffected control cohort.

METHODS

Individuals with dystonia (n = 76) were identified from the UK Biobank using published algorithms, alongside an age- and sex-matched unaffected control cohort (n = 311). Grey matter morphometric and diffusion measures were assessed, together with white matter diffusion tensor and diffusion kurtosis metrics using tractography and tractometry. Post-hoc Neurite Orientation and Density Distribution Imaging (NODDI) was also undertaken for tracts in which significant differences were observed.

RESULTS

Grey matter tremor-specific striatal differences were observed, with higher radial kurtosis. Tractography identified no white matter differences, however segmental tractometry identified localised differences, particularly in the superior cerebellar peduncles and anterior thalamic radiations, including higher fractional anisotropy and lower orientation distribution index in dystonia, compared to controls. Additional tremor-specific changes included lower neurite density index in the anterior thalamic radiations.

CONCLUSIONS

Analysis of imaging data from one of the largest dystonia cohorts to date demonstrates microstructural differences in cerebellar and thalamic white matter connections, with architectural differences such as less orientation dispersion potentially being a component of the morphological structural changes implicated in dystonia. Distinct tremor-related imaging features are also implicated in both grey and white matter.

Rare genetic brain disorders with overlapping neurological and psychiatric phenotypes

Understanding rare genetic brain disorders with overlapping neurological and psychiatric phenotypes is of increasing importance given the potential for developing disease models that could help to understand more common, polygenic disorders. However, the traditional clinical boundaries between neurology and psychiatry result in frequent segregation of these disorders into distinct silos, limiting cross-specialty understanding that could facilitate clinical and biological advances. In this Review, we highlight multiple genetic brain disorders in which neurological and psychiatric phenotypes are observed, but for which in-depth, cross-spectrum clinical phenotyping is rarely undertaken. We describe the combined phenotypes observed in association with genetic variants linked to epilepsy, dystonia, autism spectrum disorder and schizophrenia. We also consider common underlying mechanisms that centre on synaptic plasticity, including changes to synaptic and neuronal structure, calcium handling and the balance of excitatory and inhibitory neuronal activity. Further investigation is needed to better define and replicate these phenotypes in larger cohorts, which would help to gain greater understanding of the pathophysiological mechanisms and identify common therapeutic targets.

Accelerometer-derived sleep measures in idiopathic dystonia: A UK Biobank cohort study

BACKGROUND

Sleep disturbance is an increasingly recognized non-motor trait in dystonia, with varying findings reported to date. Here, we examine sleep in a UK Biobank derived dystonia cohort using subjective self-reported sleep symptoms and objective accelerometer-derived sleep measures, with comparison to a control population.

METHODS

A total of 241 dystonia cases were compared to 964 matched controls in analysis of self-reported sleep symptoms and changes in sleep architecture using wrist-worn triaxial accelerometers.

RESULTS

Dystonia participants had poorer self-reported sleep patterns compared to controls. Accelerometery measurements demonstrated later sleep times, reduced time in bed, and shifts in circadian rhythm. No association was observed with pain, and only limited relationships with psychiatric symptoms.

DISCUSSION

This study demonstrates the utility of accelerometers in longer term evaluation of sleep in dystonia, for measurement of disturbance and response to treatment. Compared to controls, altered sleep and circadian rhythm were more common in dystonia patients which may contribute to the clinical phenotype.

Wearable movement-tracking data identify Parkinson's disease years before clinical diagnosis

Parkinson's disease is a progressive neurodegenerative movement disorder with a long latent phase and currently no disease-modifying treatments. Reliable predictive biomarkers that could transform efforts to develop neuroprotective treatments remain to be identified. Using UK Biobank, we investigated the predictive value of accelerometry in identifying prodromal Parkinson's disease in the general population and compared this digital biomarker with models based on genetics, lifestyle, blood biochemistry or prodromal symptoms data. Machine learning models trained using accelerometry data achieved better test performance in distinguishing both clinically diagnosed Parkinson's disease (n = 153) (area under precision recall curve (AUPRC) 0.14 ± 0.04) and prodromal Parkinson's disease (n = 113) up to 7 years pre-diagnosis (AUPRC 0.07 ± 0.03) from the general population (n = 33,009) compared with all other modalities tested (genetics: AUPRC = 0.01 ± 0.00, P = 2.2 × 10-3; lifestyle: AUPRC = 0.03 ± 0.04, P = 2.5 × 10-3; blood biochemistry: AUPRC = 0.01 ± 0.00, P = 4.1 × 10-3; prodromal signs: AUPRC = 0.01 ± 0.00, P = 3.6 × 10-3). Accelerometry is a potentially important, low-cost screening tool for determining people at risk of developing Parkinson's disease and identifying participants for clinical trials of neuroprotective treatments.

Ultra-strong diffusion-weighted MRI reveals cerebellar grey matter abnormalities in movement disorders

Structural brain MRI has proven invaluable in understanding movement disorder pathophysiology. However, most work has focused on grey/white matter volumetric (macrostructural) and white matter microstructural effects, limiting understanding of frequently implicated grey matter microstructural differences. Using ultra-strong spherical tensor encoding diffusion-weighted MRI, a persistent MRI signal was seen in healthy cerebellar grey matter even at high diffusion-weightings (b ​≥ 10,000 s/mm2). Quantifying the proportion of this signal (denoted fs), previously ascertained to originate from inside small spherical spaces, provides a potential proxy for cell body density. In this work, this approach was applied for the first time to a clinical cohort, including patients with diagnosed movement disorders in which the cerebellum has been implicated in symptom pathophysiology. Five control participants (control group 1, median age 24.5 years (20-39 years), imaged at two timepoints, demonstrated consistency in measurement of all three measures - MD (Mean Diffusivity) fs, and Ds (dot diffusivity)- with intraclass correlation coefficients (ICC) of 0.98, 0.86 and 0.76, respectively. Comparison with an older control group (control group 2 (n = 5), median age 51 years (43-58 years)) found no significant differences, neither with morphometric nor microstructural (MD (p = 0.36), fs (p = 0.17) and Ds (p = 0.22)) measures. The movement disorder cohort (Parkinson's Disease, n = 5, dystonia, n = 5. Spinocerebellar Ataxia 6, n = 5) when compared to the age-matched control cohort (Control Group 2) identified significantly lower MD (p < 0.0001 and p < 0.0001) and higher fs values (p < 0.0001 and p < 0.0001) in SCA6 and dystonia cohorts respectively. Lobar division of the cerebellum found these same differences in the superior and inferior posterior lobes, while no differences were seen in either the anterior lobes or with Ds measurements. In contrast to more conventional measures from diffusion tensor imaging, this framework provides enhanced specificity to differences in restricted spherical spaces in grey matter (including small cells) by eliminating signals from cerebrospinal fluid and axons. In the context of human and animal histopathology studies, these findings potentially implicate the cerebellar Purkinje and granule cells as contributors to the observed signal differences, with both cell types having been implicated in several neurological disorders through both postmortem and animal model studies. This novel microstructural imaging approach shows promise for improving movement disorder diagnosis, prognosis, and treatment.

Use of remote monitoring and integrated platform for the evaluation of sleep quality in adult-onset idiopathic cervical dystonia

BACKGROUND

Up to 70% of individuals diagnosed with adult-onset idiopathic focal cervical dystonia (AOIFCD) report difficulties with sleep. Larger cohort studies using wrist-worn accelerometer devices have emerged as an alternative to smaller polysomnography studies, in order to evaluate sleep architecture.

METHODS

To measure activity during the sleep/wake cycle, individuals wore a consumer-grade wrist device (Garmin vivosmart 4) continuously over 7 days on their non-dominant wrist, while completing a daily sleep diary and standardised sleep and non-motor questionnaires via a dedicated app. Sleep measures were derived from the captured raw triaxial acceleration and heart rate values using previously published validated algorithms.

RESULTS

Data were collected from 50 individuals diagnosed with AOIFCD and 47 age- and sex-matched controls. Those with AOIFCD self-reported significantly higher levels of excessive daytime sleepiness (p = 0.04) and impaired sleep quality (p = 0.03), while accelerometer measurements found the AOIFCD cohort to have significantly longer total sleep times (p = 0.004) and time spent in NREM sleep (p = 0.009), compared to controls. Overall, there was limited agreement between wearable-derived sleep parameters, and self-reported sleep diary and visual analogue scale records.

DISCUSSION

This study shows the potential feasibility of using consumer-grade wearable devices in estimating sleep measures at scale in dystonia cohorts. Those diagnosed with AOIFCD were observed to have altered sleep architecture, notably longer total sleep time and NREM sleep, compared to controls. These findings suggest that previously reported disruptions to brainstem circuitry and serotonin neurotransmission may contribute to both motor and sleep pathophysiology.

Longitudinal analysis of the relationship between motor and psychiatric symptoms in idiopathic dystonia

BACKGROUND AND PURPOSE

Although psychiatric diagnoses are recognized in idiopathic dystonia, no previous studies have examined the temporal relationship between idiopathic dystonia and psychiatric diagnoses at scale. Here, we determine rates of psychiatric diagnoses and psychiatric medication prescription in those diagnosed with idiopathic dystsuponia compared to matched controls.

METHODS

A longitudinal population-based cohort study using anonymized electronic health care data in Wales (UK) was conducted to identify individuals with idiopathic dystonia and comorbid psychiatric diagnoses/prescriptions between 1 January 1994 and 31 December 2017. Psychiatric diagnoses/prescriptions were identified from primary and secondary health care records.

RESULTS

Individuals with idiopathic dystonia (n = 52,589) had higher rates of psychiatric diagnosis and psychiatric medication prescription when compared to controls (n = 216,754, 43% vs. 31%, p < 0.001; 45% vs. 37.9%, p < 0.001, respectively), with depression and anxiety being most common (cases: 31% and 28%). Psychiatric diagnoses predominantly predated dystonia diagnosis, particularly in the 12 months prior to diagnosis (incidence rate ratio [IRR] = 1.98, 95% confidence interval [CI] = 1.9-2.1), with an IRR of 12.4 (95% CI = 11.8-13.1) for anxiety disorders. There was, however, an elevated rate of most psychiatric diagnoses throughout the study period, including the 12 months after dystonia diagnosis (IRR = 1.96, 95% CI = 1.85-2.07).

CONCLUSIONS

This study suggests a bidirectional relationship between psychiatric disorders and dystonia, particularly with mood disorders. Psychiatric and motor symptoms in dystonia may have common aetiological mechanisms, with psychiatric disorders potentially forming prodromal symptoms of idiopathic dystonia.

Cognitive and Neuropsychiatric Impairment in Dystonia

PURPOSE OF REVIEW

To review recent literature evaluating psychiatric and cognitive symptoms in dystonia, the two non-motor symptom groups most frequently evaluated in dystonia research and recognised in clinical practice.

RECENT FINDINGS

Recent work has embedded clinical recognition of psychiatric symptoms in dystonia, with depressive and anxiety-related symptoms routinely observed to be the most common. Less explored symptoms, such as self-harm, suicidal ideation, and substance abuse, represent newer areas of investigation, with initial work suggesting higher rates than the background population. Investigation of cognitive function has provided less consistent results, both within individual dystonia subtypes and across the spectrum of dystonias, partly reflecting the heterogeneity in approaches to assessment. However, recent work indicates impairments of higher cognitive function, e.g. social cognition, and disrupted visual and auditory sensory processing. Dystonia demonstrates psychiatric and cognitive symptom heterogeneity, with further work needed to recognise endophenotypes and improve diagnostic accuracy, symptom recognition, and management.

The Genetic Landscape of Complex Childhood-Onset Hyperkinetic Movement Disorders

BACKGROUND AND OBJECTIVE

The objective of this study was to better delineate the genetic landscape and key clinical characteristics of complex, early-onset, monogenic hyperkinetic movement disorders.

METHODS

Patients were recruited from 14 international centers. Participating clinicians completed standardized proformas capturing demographic, clinical, and genetic data. Two pediatric movement disorder experts reviewed available video footage, classifying hyperkinetic movements according to published criteria.

RESULTS

One hundred forty patients with pathogenic variants in 17 different genes (ADCY5, ATP1A3, DDC, DHPR, FOXG1, GCH1, GNAO1, KMT2B, MICU1, NKX2.1, PDE10A, PTPS, SGCE, SLC2A1, SLC6A3, SPR, and TH) were identified. In the majority, hyperkinetic movements were generalized (77%), with most patients (69%) manifesting combined motor semiologies. Parkinsonism-dystonia was characteristic of primary neurotransmitter disorders (DDC, DHPR, PTPS, SLC6A3, SPR, TH); chorea predominated in ADCY5-, ATP1A3-, FOXG1-, NKX2.1-, SLC2A1-, GNAO1-, and PDE10A-related disorders; and stereotypies were a prominent feature in FOXG1- and GNAO1-related disease. Those with generalized hyperkinetic movements had an earlier disease onset than those with focal/segmental distribution (2.5 ± 0.3 vs. 4.7 ± 0.7 years; P = 0.007). Patients with developmental delay also presented with hyperkinetic movements earlier than those with normal neurodevelopment (1.5 ± 2.9 vs. 4.7 ± 3.8 years; P &lt; 0.001). Effective disease-specific therapies included dopaminergic agents for neurotransmitters disorders, ketogenic diet for glucose transporter deficiency, and deep brain stimulation for SGCE-, KMT2B-, and GNAO1-related hyperkinesia.

CONCLUSIONS

This study highlights the complex phenotypes observed in children with genetic hyperkinetic movement disorders that can lead to diagnostic difficulty. We provide a comprehensive analysis of motor semiology to guide physicians in the genetic investigation of these patients, to facilitate early diagnosis, precision medicine treatments, and genetic counseling. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Structural magnetic resonance imaging in dystonia: A systematic review of methodological approaches and findings

BACKGROUND AND PURPOSE

Structural magnetic resonance techniques have been widely applied in neurological disorders to better understand tissue changes, probing characteristics such as volume, iron deposition and diffusion. Dystonia is a hyperkinetic movement disorder, resulting in abnormal postures and pain. Its pathophysiology is poorly understood, with normal routine clinical imaging in idiopathic forms. More advanced tools provide an opportunity to identify smaller scale structural changes which may underpin pathophysiology. This review aims to provide an overview of methodological approaches undertaken in structural brain imaging of dystonia cohorts, and to identify commonly identified pathways, networks or regions that are implicated in pathogenesis.

METHODS

Structural magnetic resonance imaging studies of idiopathic and genetic forms of dystonia were systematically reviewed. Adhering to strict inclusion and exclusion criteria, PubMed and Embase databases were searched up to January 2022, with studies reviewed for methodological quality and key findings.

RESULTS

Seventy-seven studies were included, involving 1945 participants. The majority of studies employed diffusion tensor imaging (DTI) (n = 45) or volumetric analyses (n = 37), with frequently implicated areas of abnormality in the brainstem, cerebellum, basal ganglia and sensorimotor cortex and their interconnecting white matter pathways. Genotypic and motor phenotypic variation emerged, for example fewer cerebello-thalamic tractography streamlines in genetic forms than idiopathic and higher grey matter volumes in task-specific than non-task-specific dystonias.

DISCUSSION

Work to date suggests microstructural brain changes in those diagnosed with dystonia, although the underlying nature of these changes remains undetermined. Employment of techniques such as multiple diffusion weightings or multi-exponential relaxometry has the potential to enhance understanding of these differences.

Adult-onset idiopathic dystonia: A national data-linkage study to determine epidemiological, social deprivation, and mortality characteristics

BACKGROUND AND PURPOSE

Accurate epidemiological information is essential for the improved understanding of dystonia syndromes, as well as better provisioning of clinical services and providing context for diagnostic decision-making. Here, we determine epidemiological, social deprivation, and mortality characteristics of adult-onset idiopathic dystonia in the Welsh population.

METHODS

A retrospective population-based cohort study using anonymized electronic health care data in Wales was conducted to identify individuals with dystonia between 1 January 1994 and 31 December 2017. We developed a case-ascertainment algorithm to determine dystonia incidence and prevalence, as well as characterization of the dystonia cohort, based on social deprivation and mortality.

RESULTS

The case-ascertainment algorithm (79% sensitivity) identified 54,966 cases; of these cases, 41,660 had adult-onset idiopathic dystonia (≥20 years). Amongst the adult-onset form, the median age at diagnosis was 41 years, with males significantly older at time of diagnosis compared to females. Prevalence rates ranged from 0.02% in 1994 to 1.2% in 2017. The average annual incidence was 87.7/100,000/year, increasing from 49.9/100,000/year (1994) to 96.21/100,000/year (2017). In 2017, people with dystonia had a similar life expectancy to the Welsh population.

CONCLUSIONS

We have developed a case-ascertainment algorithm, supported by the introduction of a neurologist-reviewed validation cohort, providing a platform for future population-based dystonia studies. We have established robust population-level prevalence and incidence values for adult-onset idiopathic forms of dystonia, with this reflecting increasing clinical recognition and identification of causal genes. Underlying causes of death mirrored those of the general population, including circulatory disorders, respiratory disorders, cancers, and dementia.

Internet-based cognitive behavioural therapy as a feasible treatment of adult-onset, focal, isolated, idiopathic cervical dystonia

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Internet-based CBT is feasible for individuals with adult-onset cervical dystonia.

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Internet-based CBT reduces depression and anxiety in adult-onset cervical dystonia.

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Effects from internet-based CBT are sustained in some individuals at six months.

Introduction

Psychiatric symptoms are well recognised co-morbid traits in adult-onset idiopathic, isolated, focal cervical dystonia (AOIFCD), although few studies have sought to address their management. Internet-based cognitive behavioural therapy (iCBT) may provide an accessible solution. Here, we determine the feasibility of using iCBT in the management of non-motor symptoms for individuals with AOIFCD.

Methods

Participants were randomised to receive an 8-week iCBT programme (n = 10) or not (n = 10), both alongside routine clinical care. All participants underwent assessments at baseline, 3-, and 6- months for anxiety, depression, quality of life and motor symptoms, and engagement with iCBT was recorded. Group differences over time were determined using two-way mixed ANOVA, and simple statistics evaluated change on an individual participant level.

Results

Over half of participants receiving iCBT (6/10) showed high engagement, with feedback indicating most participants found iCBT useful (6/8), would continue to use it (7/8), and try it again if offered (7/8). Although no between-group significant differences were observed (e.g. Beck’s Depression Inventory p = 0.067) anxiety and depression levels showed trends towards improvement at 3-months in those receiving iCBT. Individual level analysis also indicated higher percentage level improvements in these symptoms, with this sustained in 86% participants.

Conclusion

iCBT represents a feasible therapeutic option in the management of co-morbid anxiety and depression in AOIFCD. Further work is needed to replicate these findings in a larger cohort, identify those most likely to benefit from this form of therapy and overcome barriers hindering those less likely to engage with this form of treatment.

Non-motor phenotypic subgroups in adult-onset idiopathic, isolated, focal cervical dystonia

BACKGROUND

Non-motor symptoms are well established phenotypic components of adult-onset idiopathic, isolated, focal cervical dystonia (AOIFCD). However, improved understanding of their clinical heterogeneity is needed to better target therapeutic intervention. Here, we examine non-motor phenotypic features to identify possible AOIFCD subgroups.

METHODS

Participants diagnosed with AOIFCD were recruited via specialist neurology clinics (dystonia wales: n = 114, dystonia coalition: n = 183). Non-motor assessment included psychiatric symptoms, pain, sleep disturbance, and quality of life, assessed using self-completed questionnaires or face-to-face assessment. Both cohorts were analyzed independently using Cluster, and Bayesian multiple mixed model phenotype analyses to investigate the relationship between non-motor symptoms and determine evidence of phenotypic subgroups.

RESULTS

Independent cluster analysis of the two cohorts suggests two predominant phenotypic subgroups, one consisting of approximately a third of participants in both cohorts, experiencing increased levels of depression, anxiety, sleep impairment, and pain catastrophizing, as well as, decreased quality of life. The Bayesian approach reinforced this with the primary axis, which explained the majority of the variance, in each cohort being associated with psychiatric symptomology, and also sleep impairment and pain catastrophizing in the Dystonia Wales cohort.

CONCLUSIONS

Non-motor symptoms accompanying AOIFCD parse into two predominant phenotypic sub-groups, with differences in psychiatric symptoms, pain catastrophizing, sleep quality, and quality of life. Improved understanding of these symptom groups will enable better targeted pathophysiological investigation and future therapeutic intervention.

Sleep disturbance in movement disorders: insights, treatments and challenges

Sleep and circadian rhythm disturbances are central features of many movement disorders, exacerbating motor and non-motor symptoms and impairing quality of life. Understanding these disturbances to sleep is clinically important and may further our understanding of the underlying movement disorder. This review evaluates the current anatomical and neurochemical understanding of normal sleep and the recognised primary sleep disorders. In addition, we undertook a systematic review of the evidence for disruption to sleep across multiple movement disorders. Rapid eye movement sleep behaviour disorder has emerged as the most reliable prodromal biomarker for the alpha synucleinopathies, including Parkinson's disease and multiple system atrophy, often preceding motor symptom onset by several years. Abnormal sleep has also been described for many other movement disorders, but further evidence is needed to determine whether this is a primary or secondary phenotypic component of the underlying condition. Medication used in the treatment of motor symptoms also affects sleep and can aggravate or cause certain sleep disorders. Within the context of movement disorders, there is also some suggestion of a shared underlying mechanism for motor and sleep pathophysiology, with evidence implicating thalamic and brainstem structures and monoaminergic neurotransmission. This review highlights the need for an understanding of normal and abnormal sleep within the movement disorder clinic, an ability to screen for specific causes of poor sleep and to treat sleep disturbance to improve quality of life. Key sleep disorders also act as important biomarkers and have implications in diagnosis, prognosis and the development of future therapies.

Loss-of-Function Variants in HOPS Complex Genes VPS16 and VPS41 Cause Early Onset Dystonia Associated with Lysosomal Abnormalities

OBJECTIVES

The majority of people with suspected genetic dystonia remain undiagnosed after maximal investigation, implying that a number of causative genes have not yet been recognized. We aimed to investigate this paucity of diagnoses.

METHODS

We undertook weighted burden analysis of whole-exome sequencing (WES) data from 138 individuals with unresolved generalized dystonia of suspected genetic etiology, followed by additional case-finding from international databases, first for the gene implicated by the burden analysis (VPS16), and then for other functionally related genes. Electron microscopy was performed on patient-derived cells.

RESULTS

Analysis revealed a significant burden for VPS16 (Fisher's exact test p value, 6.9 × 10⁹ ). VPS16 encodes a subunit of the homotypic fusion and vacuole protein sorting (HOPS) complex, which plays a key role in autophagosome-lysosome fusion. A total of 18 individuals harboring heterozygous loss-of-function VPS16 variants, and one with a microdeletion, were identified. These individuals experienced early onset progressive dystonia with predominant cervical, bulbar, orofacial, and upper limb involvement. Some patients had a more complex phenotype with additional neuropsychiatric and/or developmental comorbidities. We also identified biallelic loss-of-function variants in VPS41, another HOPS-complex encoding gene, in an individual with infantile-onset generalized dystonia. Electron microscopy of patient-derived lymphocytes and fibroblasts from both patients with VPS16 and VPS41 showed vacuolar abnormalities suggestive of impaired lysosomal function.

INTERPRETATION

Our study strongly supports a role for HOPS complex dysfunction in the pathogenesis of dystonia, although variants in different subunits display different phenotypic and inheritance characteristics. ANN NEUROL 2020;88:867-877.

Medical management of myoclonus-dystonia and implications for underlying pathophysiology

Myoclonus-dystonia is an early onset genetic disorder characterised by subcortical myoclonus and less prominent dystonia. Its primary causative gene is the epsilon-sarcoglycan gene but the syndrome of "myoclonic dystonia" has been shown to be a heterogeneous group of genetic disorders. The underlying pathophysiology of myoclonus-dystonia is incompletely understood, although it may relate to dysfunction of striatal monoamine neurotransmission or disruption of cerebellothalamic networks (possibly via a GABAergic deficit of Purkinje cells). A broad range of oral medical therapies have been used in the treatment of myoclonus-dystonia with a varying response, and limited data relating to efficacy and tolerability, yet this condition responds dramatically to alcohol. Few well conducted randomized controlled trials have been undertaken leading to an empirical ad hoc approach for many patients. We review the current evidence for pharmacological therapies in myoclonus-dystonia, discuss implications for underlying pathogenesis of the condition and propose a treatment algorithm for these patients.

Management of Parkinson's Disease During Pregnancy: Literature Review and Multidisciplinary Input

Background

There are no standardized clinical guidelines for the management of Parkinson's disease (PD) during pregnancy. Increasing maternal age would suggest that the incidence of pregnancy in women diagnosed with PD is likely to increase.

Objective

To evaluate the evidence for the treatment of PD during pregnancy and to canvass opinion from patients and clinical teams as to the optimum clinical management in this setting.

Methods

This involved (1) a literature review of available evidence for the use of oral medical therapy for the management of PD during pregnancy and (2) an anonymized survey of patients and clinical teams relating to previous clinical experiences.

Results

A literature review identified 31 publications (148 pregnancies, 49 PD, 2 parkinsonism, 21 dopa-responsive dystonia, 32 restless leg syndrome, 1 schizophrenia, and 43 unknown indication) detailing treatment with levodopa, and 12 publications with dopamine agonists. Adverse outcomes included seizures and congenital malformations. Survey participation included patients (n = 7), neurologists (n = 35), PD nurse specialists (n = 50), obstetricians (n = 15), and midwives (n = 20) and identified a further 34 cases of pregnancy in women with PD. Common themes for suggested management included optimization of motor symptoms, preference for levodopa monotherapy, and normal delivery unless indicated by obstetric causes.

Conclusions

This study demonstrates the paucity of evidence for decision-making in the medical management of PD during pregnancy. Collaboration is needed to develop a prospective registry, with longitudinal maternal and child health outcome measures to facilitate consensus management guidelines.

A Case of Treatment Resistance and Complications in a Patient with Stiff Person Syndrome and Cerebellar Ataxia

Background

Antibodies against glutamic acid decarboxylase (GAD) are associated with Stiff Person Syndrome (SPS).

Case report

A 50-year-old woman presented with symptoms progressed over 9 years, resulting in a cerebellar ataxia and right upper limb tremor. Investigations revealed elevated serum and CSF anti-GAD antibody titres (98.6 and 53.4 μ/ml, respectively). Treatment included intravenous immunoglobulin and immunomodulation (infliximab and rituximab), improving her stiffness, but with no impact on the ataxia-related symptoms. Subsequent high-dose steroids led to diabetic ketoacidosis and unmasking of an insulin-dependent diabetes mellitus.

Discussion

This case illustrates several key features: (1) the combined clinical picture of SPS and cerebellar ataxia is a rare phenotype associated with anti-GAD antibodies; (2) the cerebellar ataxia described was progressive and poorly responsive to immunomodulatory therapy; and (3) the potential for development of further autoimmune sequelae in response to immunosuppression, namely, the development of insulin-dependent diabetes in response to treatment with high-dose oral steroids.

Using kinematic analyses to explore sensorimotor control impairments in children with 22q11.2 deletion syndrome

BACKGROUND

The 22q11.2 deletion is associated with psychiatric and behavioural disorders, intellectual disability and multiple physical abnormalities. Recent research also indicates impaired coordination skills may be part of the clinical phenotype. This study aimed to characterise sensorimotor control abilities in children with 22q11.2 deletion syndrome (22q11.2DS) and investigate their relationships with co-occurring IQ impairments and psychopathology.

METHODS

Fifty-four children with 22q11.2DS and 24 unaffected sibling controls, comparable in age and gender, underwent kinematic analysis of their hand movements, whilst performing a battery of three visuo-manual coordination tasks that measured their tracking, aiming and steering abilities. Additionally, standardised assessments of full-scale IQ (FSIQ), attention deficit hyperactivity disorder, indicative autism spectrum disorder (ASD) and anxiety disorder symptomatology were conducted.

RESULTS

Children with 22q11.2DS showed deficits on seven of eight kinematic descriptors of movement quality across the three coordination tasks, compared to controls. Within 22q11.2DS cases, the extent of impairment on only three kinematic descriptors was significantly related to FSIQ after correction for multiple testing. Moreover, only error whilst visuo-manually tracking was nominally associated with ADHD symptom counts.

CONCLUSIONS

Impairments in sensorimotor control are seen on a range of visuo-manual tasks in children with 22q11.2DS but the extent of these impairments are largely unrelated to the severity of other psychopathological and intellectual impairments commonly found in children with 22q11.2DS.

Motor and non-motor determinants of health-related quality of life in young dystonia patients

OBJECTIVES

To systematically investigate the relationship between motor and non-motor symptoms, and health-related quality of life (HR-QoL) in children and young adults with dystonia.

METHODS

In this prospective observational cross-sectional study, 60 patients (6-25 years) with childhood-onset dystonia underwent a multidisciplinary assessment of dystonia severity (Burke-Fahn-Marsden Dystonia Rating Scale, Global Clinical Impression), motor function (Gross Motor Function Measure, Melbourne Assessment of Unilateral Upper Limb Function), pain (visual analogue scale), intelligence (Wechsler Intelligence Scale), executive functioning (Behavior Rating Inventory of Executive Function) and anxiety/depression (Child/Adult Behavior Checklist). Measures were analyzed using a principal component analysis and subsequent multiple regression to evaluate which components were associated with HR-QoL (Pediatric Quality of life Inventory) for total group, and non-lesional (primary) and lesional (secondary) subgroups.

RESULTS

Patients (29 non-lesional, 31 lesional dystonia) had a mean age of 13.6 ± 5.9 years. The principal component analysis revealed three components: 1) motor symptoms; 2) psychiatric and behavioral symptoms; and 3) pain. HR-QoL was associated with motor symptoms and psychiatric and behavioral symptoms (R2 = 0.66) for the total sample and lesional dystonia, but in the non-lesional dystonia subgroup only with psychiatric and behavioral symptoms (R2 = 0.51).

CONCLUSIONS

Non-motor symptoms are important for HR-QoL in childhood-onset dystonia. We suggest a multidisciplinary assessment of motor and non-motor symptoms to optimize individual patient management.

Dentatorubral-pallidoluysian Atrophy: An Update

Background

Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare, autosomal dominantly inherited disorder characterized by myoclonus, epilepsy, ataxia, and dementia. Diagnosis is challenging due to the heterogeneous presentation and symptomatic overlap with other spinocerebellar ataxias. Symptoms vary according to age of onset, with a mean age at onset of 31 years. A CAG repeat expansion in the ATN1 gene results in neuronal intranuclear inclusions, variable neuronal loss, and astrocytosis in the globus pallidus, dentate and red nuclei. No disease-modifying or curative treatments are currently available

Methods

We performed an online literature search using PubMed for all articles published in an English Language format on the topics of DRPLA or ATN1 over the last 10 years. Where these articles cited other research as support for findings, or statements, these articles were also reviewed. Contemporary articles from related research fields (e.g., Huntington’s Disease) were also included to support statements.

Results

Forty-seven articles were identified, 10 were unobtainable and 10 provided no relevant information. The remaining 27 articles were then used for the review template: seven case reports, seven case series, six model system articles (one review article), four population clinical and genetic studies (one review article), two general review articles, and one human gene expression study. Other cited articles or research from related fields gave a further 42 articles, producing a total of 69 articles cited: 15 case series (including eight family studies), 14 model systems (one review article), 14 population clinical and genetic studies (two review articles), 10 case reports, eight clinical trials/guidelines, four genetic methodology articles, three general review articles, and one human gene expression study.

Discussion

DRPLA remains an intractable, progressive, neurodegenerative disorder without effective treatment. Early recognition of the disorder may improve patient understanding, and access to services and treatments. Large-scale studies are lacking, but are required to characterize the full allelic architecture of the disorder in all populations and the heterogeneous phenotypic spectrum, including neuroimaging findings, possible biomarkers, and responses to treatment.

Electrophysiologic testing aids diagnosis and subtyping of myoclonus

OBJECTIVE

To determine the contribution of electrophysiologic testing in the diagnosis and anatomical classification of myoclonus.

METHODS

Participants with a clinical diagnosis of myoclonus were prospectively recruited, each undergoing a videotaped clinical examination and battery of electrophysiologic tests. The diagnosis of myoclonus and its subtype was reviewed after 6 months in the context of the electrophysiologic findings and specialist review of the videotaped clinical examination.

RESULTS

Seventy-two patients with myoclonus were recruited. Initial clinical anatomical classification included 25 patients with cortical myoclonus, 7 with subcortical myoclonus, 2 with spinal myoclonus, and 15 with functional myoclonic jerks. In 23 cases, clinical anatomical classification was not possible because of the complexity of the movement disorder. Electrophysiologic testing was completed in 66, with agreement of myoclonus in 60 (91%) and its subtype in 28 (47%) cases. Subsequent clinical review by a movement disorder specialist agreed with the electrophysiologic findings in 52 of 60; in the remaining 8, electrophysiologic testing was inconclusive.

CONCLUSIONS

Electrophysiologic testing is an important additional tool in the diagnosis and anatomical classification of myoclonus, also aiding in decision-making regarding therapeutic management. Further development of testing criteria is necessary to optimize its use in clinical practice.

A review of psychiatric co-morbidity described in genetic and immune mediated movement disorders

Psychiatric symptoms are an increasingly recognised feature of movement disorders. Recent identification of causative genes and autoantibodies has allowed detailed analysis of aetiologically homogenous subgroups, thereby enabling determination of the spectrum of psychiatric symptoms in these disorders. This review evaluates the incidence and type of psychiatric symptoms encountered in patients with movement disorders. A broad spectrum of psychiatric symptoms was identified across all subtypes of movement disorder, with depression, generalised anxiety disorder and obsessive-compulsive disorder being most common. Psychosis, schizophrenia and attention deficit hyperactivity disorder were also identified, with the psychiatric symptoms often predating onset of the motor disorder. The high incidence of psychiatric symptoms across such a wide range of movement disorders suggests a degree of common or overlapping pathogenic mechanisms. Our review demonstrates the need for increased clinical awareness of such co-morbidities, which should facilitate early neuropsychiatric intervention and allied specialist treatment for patients.

Clinical characterization of dystonia in adult patients with Huntington's disease

BACKGROUND AND PURPOSE

Huntington's disease (HD) is an autosomal dominant, neurodegenerative movement disorder, typically characterized by chorea. Dystonia is also recognized as part of the HD motor phenotype, although little work detailing its prevalence, distribution, severity and impact on functional capacity has been published to date.

METHODS

Patients (>18 years of age) were recruited from the Cardiff (UK) HD clinic, each undergoing a standardized videotaped clinical examination and series of functional assessment questionnaires (Unified Huntington's Disease Rating Scale, Burke-Fahn-Marsden Dystonia Rating Scale and modified version of the Toronto Western Spasmodic Torticollis Rating Scale). The presence and severity of dystonia were scored by four independent neurologists using the Burke-Fahn-Marsden Dystonia Rating Scale and Unified Huntington's Disease Rating Scale. Statistical analysis included Fisher's exact test, Wilcoxon test, anova and calculation of correlation coefficients where appropriate.

RESULTS

Forty-eight patients [91% (48/53)] demonstrated evidence of dystonia, with the highest prevalence in the left upper limb (n = 44, 83%), right upper limb most severely affected and eyes least affected. Statistically significant positive correlations (P < 0.05) were observed between dystonia severity and increasing HD disease stage and motor disease duration. Deterioration in functional capacity also correlated with increasing dystonia severity. No significant relationship was observed with age at motor symptom onset or CAG repeat length.

CONCLUSIONS

We report a high prevalence of dystonia in adult patients with HD, with worsening dystonia severity with increasing HD disease stage and motor disease duration. The recognition and management of dystonic symptoms in routine clinical practice will aid overall symptomatic treatment and functional improvement.

The long-term neuropsychological features of basal ganglia encephalitis

This commentary is on the case report by Pawela et al. on pages 445–48 of this issue.

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.

Nitrous oxide misuse and vitamin B12 deficiency

A 36-year-old man presented to hospital with a 5-week history of ascending limb paraesthesiae and balance difficulties. He had no medical or travel history of note, but admitted habitual nitrous oxide (N2O) inhalation. Neurological examination revealed a sensory ataxia with pseudoathetosis in the upper limbs and reduced vibration sensation to the hips bilaterally. Significant investigation results included a low serum vitamin B12 concentration, mild macrocytosis and raised serum homocysteine concentration. T2 MRI of the spinal cord demonstrated increased signal extending from C1 to T11 in keeping with a longitudinal myelitis. The patient was diagnosed with a myeloneuropathy secondary to vitamin B12 deficiency, resulting from heavy N2O inhalation. He was treated with intramuscular vitamin B12 injections and received regular physiotherapy. At discharge, he was able to mobilise short distances with the aid of a zimmer frame, and was independently mobile 8 weeks later.

Distribution and Coexistence of Myoclonus and Dystonia as Clinical Predictors of SGCE Mutation Status: A Pilot Study

Introduction

Myoclonus–dystonia (M–D) is a young onset movement disorder typically involving myoclonus and dystonia of the upper body. A proportion of the cases are caused by mutations to the autosomal dominantly inherited, maternally imprinted, epsilon-sarcoglycan gene (SGCE). Despite several sets of diagnostic criteria, identification of patients most likely to have an SGCE mutation remains difficult.

Methods

Forty consecutive patients meeting pre-existing diagnostic clinical criteria for M–D underwent a standardized clinical examination (20 SGCE mutation positive and 20 negative). Each video was reviewed and systematically scored by two assessors blinded to mutation status. In addition, the presence and coexistence of myoclonus and dystonia was recorded in four body regions (neck, arms, legs, and trunk) at rest and with action.

Results

Thirty-nine patients were included in the study (one case was excluded owing to insufficient video footage). Based on previously proposed diagnostic criteria, patients were subdivided into 24 “definite,” 5 “probable,” and 10 “possible” M–D. Motor symptom severity was higher in the SGCE mutation-negative group. Myoclonus and dystonia were most commonly observed in the neck and upper limbs of both groups. Truncal dystonia with action was significantly seen more in the mutation-negative group (p < 0.05). Coexistence of myoclonus and dystonia in the same body part with action was more commonly seen in the mutation-negative cohort (p < 0.05).

Conclusion

Truncal action dystonia and coexistence of myoclonus and dystonia in the same body part with action might suggest the presence of an alternative mutation in patients with M–D.

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.

Psychiatric disorders, myoclonus dystonia and SGCE: an international study

Objective

Myoclonus‐dystonia (M‐D) is a hyperkinetic movement disorder, typically alcohol‐responsive upper body myoclonus and dystonia. The majority of autosomal dominant familial cases are caused by epsilon‐sarcoglycan gene (SGCE) mutations. Previous publications have observed increased rates of psychiatric disorders amongst SGCE mutation‐positive populations. We analyzed the psychiatric data from four international centers, forming the largest cohort to date, to further determine the extent and type of psychiatric disorders in M‐D.

Methods

Psychiatric data from SGCE mutation‐positive M‐D cohorts, collected by movement disorder specialists in the Netherlands, United Kingdom, United States, and Germany, were analyzed. These data were collected using standardized, systematic questionnaires allowing classification of symptoms according to Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM‐IV) criteria. Based on motor findings and SGCE mutation analysis, participants were classified into one of three groups: manifesting carriers, nonmanifesting carriers and noncarriers.

Results

Data from 307 participants were evaluated (140 males, 167 females, mean age at examination: 42.5 years). Two‐thirds of motor affected mutation carriers (n = 132) had ≥1 psychiatric diagnosis, specific, and social phobias being most common followed by alcohol dependence and obsessive‐compulsive disorder (OCD). Compared to familial controls, affected mutation carriers had significantly elevated overall rates of psychiatric disorders (P < 0.001). The most significant differences were observed with alcohol dependence (P < 0.001), OCD (P < 0.001), social and specific phobias (P < 0.001).

Interpretation

M‐D due to SGCE mutations is associated with specific psychiatric disorders, most commonly OCD, anxiety‐related disorders, and alcohol dependence. These suggest either a potential pleiotropic function for SGCE within the central nervous system or a secondary effect of the motor disorder.

Non-motor symptoms in genetically defined dystonia: Homogenous groups require systematic assessment

INTRODUCTION

Dystonia is a movement disorder involving sustained or intermittent muscle contractions resulting in abnormal movements and postures. Identification of disease causing genes has allowed examination of genetically homogenous groups. Unlike the motor symptoms, non-motor characteristics are less clearly defined, despite their impact on a patient's quality of life. This review aims to examine the evidence for non-motor symptoms, addressing cohort size and methods of assessment in each study.

METHODS

A systematic and standardised search strategy was used to identify the published literature relating to psychiatric symptoms, cognition, sleep disorders, sensory abnormalities and pain in each of the genetically determined dystonias. Studies were divided according to cohort size, method of assessment and whether comparison was made to an appropriate control group.

RESULTS

Ninety-five articles were identified including reported clinical histories (n = 42), case reports and smaller case series (n = 12), larger case series (n = 23) and case-control cohorts (n = 18). Psychiatric symptoms were the most frequently investigated with anxiety, depression and Obsessive-Compulsive disorder being most common. Cognitive impairment involved either global deficits or isolated difficulties in specific domains. Disturbances to sleep were most common in the dopa-responsive dystonias. Sensory testing in DYT1 cases identified an intermediate subclinical phenotype.

CONCLUSION

Non-motor symptoms form an integral component of the dystonia phenotype. However, future studies should involve a complete assessment of all symptom subtypes in order to understand the frequency and gene-specificity of these symptoms. This will enable early symptom identification, appropriate clinical management, and provide additional outcome measures in future clinical trials.

Benign Hereditary Chorea: An Update

Benign hereditary chorea (BHC) is a childhood-onset, hyperkinetic movement disorder normally with little progression of motor symptoms into adult life. The disorder is caused by mutations to the NKX2.1 (TITF1) gene and also forms part of the “brain–lung–thyroid syndrome”, in which additional developmental abnormalities of lung and thyroid tissue are observed. In this review, we summarize the main clinical findings in “classical” BHC syndrome and discuss more recently reported atypical features, including non-choreiform movement phenotypes. We highlight additional non-motor characteristics such as cognitive impairment and psychiatric symptoms, while discussing the evidence for BHC as a developmental disorder involving impaired neural migration and other multisystem developmental abnormalities. Finally, we will discuss the efficacy of available therapies in both affected pediatric and adult cohorts. Delineation of the BHC disease spectrum will no doubt expand our understanding of this disorder, facilitating better targeting of genetic testing and establish a framework for future clinical trials.

Rare inborn errors of metabolism with movement disorders: a case study to evaluate the impact upon quality of life and adaptive functioning

Background

Inborn errors of metabolism (IEM) form an important cause of movement disorders in children. The impact of metabolic diseases and concordant movement disorders upon children’s health-related quality of life (HRQOL) and its physical and psychosocial domains of functioning has never been investigated. We therefore conducted a case study on the HRQOL and development of adaptive functioning in children with an IEM and a movement disorder.

Methods

Children with co-existent IEM and movement disorders were recruited from paediatric outpatient clinics. We systematically collected clinical data and videotaped examinations. The movement disorders were diagnosed by a panel of specialists. The Pediatric Quality of Life Inventory 4.0 and the Vineland Adaptive Behavior Scale were used to assess the HRQOL and adaptive functioning, respectively.

Results

We recruited 24 children (10 boys, mean age 7y 5 m). Six types of movement disorders were recognised by the expert panel, most frequently dystonia (16/24), myoclonus (7/24) and ataxia (6/24). Mean HRQOL (49.63, SD 21.78) was significantly lower than for other chronic disorders in childhood (e.g. malignancy, diabetes mellitus, rheumatic disease, psychiatric disorders; p <0.001) and tended to diminish with the severity of the movement disorder. The majority of participants had delayed adaptive functioning, most evident in their activities of daily living (51.92%, SD 27.34). Delay in adaptive functioning had a significant impact upon HRQOL (p = 0.018).

Conclusions

A broad spectrum of movement disorders was seen in patients with IEM, although only five were receiving treatment. The overall HRQOL in this population is significantly reduced. Delay in adaptive functioning, most frequently seen in relation to activities of daily living, and the severity of the movement disorder contribute to this lower HRQOL. We plead for a greater awareness of movement disorders and that specialists should be asked to diagnose and treat these wherever possible.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0177-6) contains supplementary material, which is available to authorized users.

Benign hereditary chorea related to NKX2.1: expansion of the genotypic and phenotypic spectrum

AIM

Benign hereditary chorea is a dominantly inherited, childhood-onset hyperkinetic movement disorder characterized by non-progressive chorea and variable degrees of thyroid and respiratory involvement. Loss-of-function mutations in NKX2.1, a gene vital to the normal development and function of the brain, lungs, and thyroid, have been identified in a number of individuals.

METHOD

Clinical data from individuals with benign hereditary chorea identified through paediatric neurology services were collected in a standardized format. The NKX2.1 gene was analysed by Sanger sequencing, multiplex ligation-dependent probe amplification, and microarray analysis.

RESULTS

Six of our cohort were female and four male, median age at assessment was 8 years 6 months (range 1 y 6 mo-18 y). We identified 10 probands with NKX2.1 mutations; nine of these mutations are novel (including two whole-gene deletions) and one has been previously reported. Of the 10 individuals, eight presented with muscle hypotonia and four had evidence of hypothyroidism or respiratory involvement. Only three out of the 10 individuals had the full triad of 'brain-lung-thyroid syndrome' symptoms. Additional clinical characteristics occurring in individual participants included growth hormone deficiency, pes cavus, kyphosis, duplex kidney, and obsessive-compulsive disorder.

INTERPRETATION

Our data suggest that the neurological phenotype is prominent in this condition and that many patients with benign hereditary chorea do not have the classic triad of brain-lung-thyroid syndrome. The extended phenotype may include obsessive-compulsive disorder and skeletal abnormalities.

SGCE mutations cause psychiatric disorders: clinical and genetic characterization

Myoclonus dystonia syndrome is a childhood onset hyperkinetic movement disorder characterized by predominant alcohol responsive upper body myoclonus and dystonia. A proportion of cases are due to mutations in the maternally imprinted SGCE gene. Previous studies have suggested that patients with SGCE mutations may have an increased rate of psychiatric disorders. We established a cohort of patients with myoclonus dystonia syndrome and SGCE mutations to determine the extent to which psychiatric disorders form part of the disease phenotype. In all, 89 patients with clinically suspected myoclonus dystonia syndrome were recruited from the UK and Ireland. SGCE was analysed using direct sequencing and for copy number variants. In those patients where no mutation was found TOR1A (GAG deletion), GCH1, THAP1 and NKX2-1 were also sequenced. SGCE mutation positive cases were systematically assessed using standardized psychiatric interviews and questionnaires and compared with a disability-matched control group of patients with alcohol responsive tremor. Nineteen (21%) probands had a SGCE mutation, five of which were novel. Recruitment of family members increased the affected SGCE mutation positive group to 27 of whom 21 (77%) had psychiatric symptoms. Obsessive-compulsive disorder was eight times more likely (P < 0.001) in mutation positive cases, compulsivity being the predominant feature (P < 0.001). Generalized anxiety disorder (P = 0.003) and alcohol dependence (P = 0.02) were five times more likely in mutation positive cases than tremor controls. SGCE mutations are associated with a specific psychiatric phenotype consisting of compulsivity, anxiety and alcoholism in addition to the characteristic motor phenotype. SGCE mutations are likely to have a pleiotropic effect in causing both motor and specific psychiatric symptoms.