Psychiatric Manifestations of ATP13A2 Mutations

Background

Biallelic mutations in ATP13A2 were identified as the cause of Kufor‐Rakeb disease, a pallido‐pyramidal syndrome characterized by young‐onset dystonia–parkinsonism with vertical supranuclear gaze palsy, spasticity, and cognitive decline. The phenotypic spectrum has broadened since, but predominantly psychiatric or behavioral manifestations have not been highlighted.

Cases

Here we report the clinical, radiological, and genetic findings in 2 unrelated patients with ATP13A2 mutations. One patient had a prominent behavioral (autistic spectrum) presentation and the other a psychiatric (paranoid psychosis) presentation. Both had additional features, such as delayed milestones, ataxia, pyramidal signs, upgaze restriction, or impaired cognition to varying extent, but these were partly subtle or developed later in the disease course.

Conclusion

Prominent behavioral or psychiatric features can be the first or most prominent manifestation of ATP13A2‐related disease. They may be a diagnostic clue in patients with ataxia, spasticity, or parkinsonism and may require an interdisciplinary neurological and psychiatric treatment approach.

Video-tutorial for the Movement Disorder Society criteria for progressive supranuclear palsy

BACKGROUND

The International Parkinson and Movement Disorder Society-endorsed Progressive Supranuclear Palsy Study Group published clinical diagnostic criteria for progressive supranuclear palsy in 2017, aiming to optimize early, sensitive and specific diagnosis.

OBJECTIVE

To assist physicians in the application of these criteria, we developed a video-based tutorial in which all core clinical features and clinical clues are depicted and explained.

METHODS

Patients provided written informed consent to the publication of their videos. High-quality videos along with essential descriptions were collected by the study group members. Most educational videos were selected in a structured consensus process.

RESULTS

We provide 68 videos of all core clinical features and clinical clues defined by the diagnostic criteria, along with instructive descriptions of the depicted patients, examination techniques and clinical findings.

CONCLUSIONS

This comprehensive video-based tutorial will support physicians in the application of the diagnostic criteria of progressive supranuclear palsy.

Isolated and combined genetic tremor syndromes: a critical appraisal based on the 2018 MDS criteria

The 2018 consensus statement on the classification of tremors proposes a two-axis categorization scheme based on clinical features and etiology. It also defines "isolated" and "combined" tremor syndromes depending on whether tremor is the sole clinical manifestation or is associated with other neurological or systemic signs. This syndromic approach provides a guide to investigate the underlying etiology of tremors, either genetic or acquired. Several genetic defects have been proven to cause tremor disorders, including autosomal dominant and recessive, X-linked, and mitochondrial diseases, as well as chromosomal abnormalities. Furthermore, some tremor syndromes are recognized in individuals with a positive family history, but their genetic confirmation is pending. Although most genetic tremor disorders show a combined clinical picture, there are some distinctive conditions in which tremor may precede the appearance of other neurological signs by years or remain the prominent manifestation throughout the disease course, previously leading to misdiagnosis as essential tremor (ET). Advances in the knowledge of genetically determined tremors may have been hampered by the inclusion of heterogeneous entities in previous studies on ET. The recent classification of tremors therefore aims to provide more consistent clinical data for deconstructing the genetic basis of tremor syndromes in the next-generation and long-read sequencing era. This review outlines the wide spectrum of tremor disorders with defined or presumed genetic etiology, both isolated and combined, unraveling diagnostic clues of these conditions and focusing mainly on ET-like phenotypes. Furthermore, we suggest a phenotype-to-genotype algorithm to support clinicians in identifying tremor syndromes and guiding genetic investigations.

Tardive syndromes

Dopamine receptor-blocking antipsychotics, first introduced into clinical practice in 1952, were hailed as a panacea in the treatment of a number of psychiatric disorders. However, within 5 years, this notion was to be shattered by the recognition of both acute and chronic drug-induced movement disorders which can accompany their administration. Tardive syndromes, denoting the delayed onset of movement disorders following administration of dopamine receptor-blocking (and also other) drugs, have diverse manifestations ranging from the classic oro-bucco-lingual dyskinesia, through dystonic craniocervical and trunk posturing, to abnormal breathing patterns. Although tardive syndromes have been an important part of movement disorder clinical practice for over 60 years, their pathophysiologic basis remains poorly understood and the optimal treatment approach remains unclear. This review summarises the current knowledge relating to these syndromes and provides clinicians with pragmatic, clinically focused guidance to their management.

MYORG-related disease is associated with central pontine calcifications and atypical parkinsonism

OBJECTIVE

To identify the phenotypic, neuroimaging, and genotype-phenotype expression of MYORG mutations.

METHODS

Using next-generation sequencing, we screened 86 patients with primary familial brain calcification (PFBC) from 60 families with autosomal recessive or absent family history that were negative for mutations in SLC20A2, PDGFRB, PDGBB, and XPR1. In-depth phenotyping and neuroimaging investigations were performed in all cases reported here.

RESULTS

We identified 12 distinct deleterious MYORG variants in 7 of the 60 families with PFBC. Overall, biallelic MYORG mutations accounted for 11.6% of PFBC families in our cohort. A heterogeneous phenotypic expression was identified within and between families with a median age at onset of 56.4 years, a variable combination of parkinsonism, cerebellar signs, and cognitive decline. Psychiatric disturbances were not a prominent feature. Cognitive assessment showed impaired cognitive function in 62.5% of cases. Parkinsonism associated with vertical nuclear gaze palsy was the initial clinical presentation in 1/3 of cases and was associated with central pontine calcifications. Cerebral cortical atrophy was present in 37% of cases.

CONCLUSIONS

This large, multicentric study shows that biallelic MYORG mutations represent a significant proportion of autosomal recessive PFBC. We recommend screening MYORG mutations in all patients with primary brain calcifications and autosomal recessive or negative family history, especially when presenting clinically as atypical parkinsonism and with pontine calcification on brain CT.

KCNN2 mutation in autosomal-dominant tremulous myoclonus-dystonia

BACKGROUND AND PURPOSE

Despite recent advances in neurogenetics that have facilitated the identification of a number of dystonia genes, many familial dystonia syndromes remain without known cause. The aim of the study was to identify the cause of autosomal dominant tremulous myoclonus-dystonia in a UK kindred with affected individuals in three generations.

METHODS

Known genetic causes of myoclonus-dystonia were excluded. We combined clinical and electrophysiological phenotyping with whole-exome sequencing and Sanger sequencing to identify candidate causal variants in a family with tremulous myoclonus-dystonia.

RESULTS

The core phenotype consisted of childhood-onset dystonia predominantly affecting hands and neck, with a fast tremor with superimposed myoclonus and, in some individuals, subtle cerebellar signs. We identified a novel missense variant in potassium calcium-activated channel subfamily N member 2 (KCNN2) [NM_021614:c.1112G>A:p.(Gly371Glu)], which was the only variant that we were able to identify as segregating with the phenotype over three generations. This variant, which is absent from the most recent version of gnomAD, was predicted to be deleterious by SIFT and PolyPhen-2 and had an overall CADD score of 29.7.

CONCLUSIONS

KCNN2, a member of the KCNN family of potassium channel genes, is highly conserved across species and in humans is highly expressed in the brain, particularly the cerebellum. KCNN2 mutations have never been described as pathological in human disease, but are recognized abnormalities in two rodent models of fast, jerky tremor. Segregation, absence of the variant in the normal population and in-silico prediction of a deleterious effect together with animal models compatible with the clinical phenotype are all in line with KCNN2 mutations being a plausible cause underlying myoclonus-dystonia.

Antibody-related movement disorders - a comprehensive review of phenotype-autoantibody correlations and a guide to testing

Background

Over the past decade increasing scientific progress in the field of autoantibody-mediated neurological diseases was achieved. Movement disorders are a frequent and often prominent feature in such diseases which are potentially treatable.

Main body

Antibody-mediated movement disorders encompass a large clinical spectrum of diverse neurologic disorders occurring either in isolation or accompanying more complex autoimmune encephalopathic diseases. Since autoimmune movement disorders can easily be misdiagnosed as neurodegenerative or metabolic conditions, appropriate immunotherapy can be delayed or even missed. Recognition of typical clinical patterns is important to reach the correct diagnosis.

Conclusion

There is a growing number of newly discovered antibodies which can cause movement disorders. Several antibodies can cause distinctive phenotypes of movement disorders which are important to be aware of. Early diagnosis is important because immunotherapy can result in major improvement.In this review article we summarize the current knowledge of autoimmune movement disorders from a point of view focused on clinical syndromes. We discuss associated clinical phenomenology and antineuronal antibodies together with alternative etiologies with the aim of providing a diagnostic framework for clinicians considering underlying autoimmunity in patients with movement disorders.

Voluntary Inhibitory Control of Chorea: A Case Series

Background

Volitional control of involuntary movements has so far been considered a hallmark of tic disorders. However, modulation of involuntary movements can also be observed in other hyperkinesias.

Cases

Here, we present 6 patients with chorea able to suppress their involuntary movements, on demand. In 3 of them, surface electromyography was used to quantify degree of suppression and confirmed a reduction of muscle activity up to 68%, during volitional control.

Conclusion

This observation represents a first step toward a description of a new clinical feature in choreic syndromes and an opportunity to redefine the role of volitional inhibition in hyperkinetic movement disorders.

Temporal discrimination is altered in patients with isolated asymmetric and jerky upper limb tremor

BACKGROUND

Unilateral or very asymmetric upper limb tremors with a jerky appearance are poorly investigated. Their clinical classification is an unsolved problem because their classification as essential tremor versus dystonic tremor is uncertain. To avoid misclassification as essential tremor or premature classification as dystonic tremor, the term indeterminate tremor was suggested.

OBJECTIVES

The aim of this study was to characterize this tremor subgroup electrophysiologically and evaluate whether diagnostically meaningful electrophysiological differences exist compared to patients with essential tremor and dystonic tremor.

METHODS

We enrolled 29 healthy subjects and 64 patients with tremor: 26 with dystonic tremor, 23 with essential tremor, and 15 patients with upper limb tremor resembling essential tremor but was unusually asymmetric and jerky (indeterminate tremor). We investigated the somatosensory temporal discrimination threshold, the short-interval intracortical inhibition, and the cortical plasticity by paired associative stimulation.

RESULTS

Somatosensory temporal discrimination threshold was significantly increased in patients with dystonic tremor and indeterminate tremor, but it was normal in the essential tremor patients and healthy controls. Significant differences in short-interval intracortical inhibition and paired associative stimulation were not found among the three patient groups and controls.

CONCLUSION

These results indicate that indeterminate tremor, as defined in this study, shares electrophysiological similarities with dystonic tremor rather than essential tremor. Therefore, we propose that indeterminate tremor should be considered as a separate clinical entity from essential tremor and that it might be dystonic in nature. Somatosensory temporal discrimination appears to be a useful tool in tremor classification. © 2019 International Parkinson and Movement Disorder Society.

The spectrum of involuntary vocalizations in humans: A video atlas

In clinical practice, involuntary vocalizing behaviors are typically associated with Tourette syndrome and other tic disorders. However, they may also be encountered throughout the entire tenor of neuropsychiatry, movement disorders, and neurodevelopmental syndromes. Importantly, involuntary vocalizing behaviors may often constitute a predominant clinical sign, and, therefore, their early recognition and appropriate classification are necessary to guide diagnosis and treatment. Clinical literature and video-documented cases on the topic are surprisingly scarce. Here, we pooled data from 5 expert centers of movement disorders, with instructive video material to cover the entire range of involuntary vocalizations in humans. Medical literature was also reviewed to document the range of possible etiologies associated with the different types of vocalizing behaviors and to explore treatment options. We propose a phenomenological classification of involuntary vocalizations within different categorical domains, including (1) tics and tic-like vocalizations, (2) vocalizations as part of stereotypies, (3) vocalizations as part of dystonia or chorea, (4) continuous vocalizing behaviors such as groaning or grunting, (5) pathological laughter and crying, (6) vocalizations resembling physiological reflexes, and (7) other vocalizations, for example, those associated with exaggerated startle responses, as part of epilepsy and sleep-related phenomena. We provide comprehensive lists of their associated etiologies, including neurodevelopmental, neurodegenerative, neuroimmunological, and structural causes and clinical clues. We then expand on the pathophysiology of the different vocalizing behaviors and comment on available treatment options. Finally, we present an algorithmic approach that covers the wide range of involuntary vocalizations in humans, with the ultimate goal of improving diagnostic accuracy and guiding appropriate treatment. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Validation of a self-completed Dystonia Non-Motor Symptoms Questionnaire

OBJECTIVE

To develop and validate a novel 14-item self-completed questionnaire (in English and German) enquiring about the presence of non-motor symptoms (NMS) during the past month in patients with craniocervical dystonia in an international multicenter study.

METHODS

The Dystonia Non-Motor Symptoms Questionnaire (DNMSQuest) covers seven domains including sleep, autonomic symptoms, fatigue, emotional well-being, stigma, activities of daily living, sensory symptoms. The feasibility and clinimetric attributes were analyzed.

RESULTS

Data from 194 patients with CD (65.6% female, mean age 58.96 ± 12.17 years, duration of disease 11.95 ± 9.40 years) and 102 age- and sex-matched healthy controls (66.7% female, mean age 55.67 ± 17.62 years) were collected from centres in Germany and the UK. The median total NMS score in CD patients was 5 (interquartile range 3-7), significantly higher than in healthy controls with 1 (interquartile range 0.75-2.25) (P < 0.001, Mann-Whitney U-test). Evidence for intercorrelation and convergent validity is shown by moderate to high correlations of total DNMSQuest score with motor symptom severity (TWSTRS: r_s  = 0.61), clinical global impression (r_s  = 0.40), and health-related quality of life measures: CDQ-24 (r_s  = 0.74), EQ-5D index (r_s  = -0.59), and scale (r_s  = -0.49) (all P < 0.001). Data quality and acceptability was very satisfactory.

INTERPRETATION

The DNMSQuest, a patient self-completed questionnaire for NMS assessment in CD patients, appears robust, reproducible, and valid in clinical practice showing a tangible impact of NMS on quality of life in CD. As there is no specific, comprehensive, validated tool to assess the burden of NMS in dystonia, the DNMSQuest can bridge this gap and could easily be integrated into clinical practice.

Twenty years on: Myoclonus-dystonia and ε-sarcoglycan - neurodevelopment, channel, and signaling dysfunction

Myoclonus-dystonia is a clinical syndrome characterized by a typical childhood onset of myoclonic jerks and dystonia involving the neck, trunk, and upper limbs. Psychiatric symptomatology, namely, alcohol dependence and phobic and obsessive-compulsive disorder, is also part of the clinical picture. Zonisamide has demonstrated effectiveness at reducing both myoclonus and dystonia, and deep brain stimulation seems to be an effective and long-lasting therapeutic option for medication-refractory cases. In a subset of patients, myoclonus-dystonia is associated with pathogenic variants in the epsilon-sarcoglycan gene, located on chromosome 7q21, and up to now, more than 100 different pathogenic variants of the epsilon-sarcoglycan gene have been described. In a few families with a clinical phenotype resembling myoclonus-dystonia associated with distinct clinical features, variants have been identified in genes involved in novel pathways such as calcium channel regulation and neurodevelopment. Because of phenotypic similarities with epsilon-sarcoglycan gene-related myoclonus-dystonia, these conditions can be collectively classified as "myoclonus-dystonia syndromes." In the present article, we present myoclonus-dystonia caused by epsilon-sarcoglycan gene mutations, with a focus on genetics and underlying disease mechanisms. Second, we review those conditions falling within the spectrum of myoclonus-dystonia syndromes, highlighting their genetic background and involved pathways. Finally, we critically discuss the normal and pathological function of the epsilon-sarcoglycan gene and its product, suggesting a role in the stabilization of the dopaminergic membrane via regulation of calcium homeostasis and in the neurodevelopmental process involving the cerebello-thalamo-pallido-cortical network. © 2019 International Parkinson and Movement Disorder Society.

Mitochondrial complex I NUBPL mutations cause combined dystonia with bilateral striatal necrosis and cerebellar atrophy

Background and purpose

The recent advances in genetics have helped to unravel the cause of many dystonia syndromes. With the broadening spectrum of genetically defined dystonia syndromes, distinct clinico‐radiological phenotypes are a welcome handle to guide the diagnostic work‐up.

Methods

Exome sequencing was used to elucidate the genetic cause of a syndrome characterized by generalized dystonia, pyramidal and cerebellar involvement, with bilateral striatal necrosis (BSN) and cerebellar atrophy on magnetic resonance imaging. Homozygosity mapping and linkage analysis were used in a supportive role. Known genetic causes of BSN were excluded by use of exome data or Sanger sequencing.

Results

Compound heterozygous mutations were identified in the NUBPL gene in a small UK kindred. The gene lay in a region of positive linkage and segregated with disease in a family of six individuals.

Conclusion

NUBPL mutations cause early onset, autosomal recessive generalized dystonia with cerebellar ataxia, pyramidal signs, preserved cognition and a distinct magnetic resonance imaging appearance with BSN and cerebellar atrophy.