Paroxysmal movement disorders

Genetic testing for non-parkinsonian movement disorders: Navigating the diagnostic maze

Genetic testing has become a valuable diagnostic tool for movement disorders due to substantial advancements in understanding their genetic basis. However, the heterogeneity of movement disorders poses a significant challenge, with many genes implicated in different subtypes. This paper aims to provide a neurologist's perspective on approaching patients with hereditary hyperkinetic disorders with a focus on select forms of dystonia, paroxysmal dyskinesia, chorea, and ataxia. Age at onset, initial symptoms, and their severity, as well as the presence of any concurrent neurological and non-neurological features, contribute to the individual clinical profiles of hereditary non-parkinsonian movement disorders, aiding in the selection of appropriate genetic testing strategies. There are also more specific diagnostic clues that may facilitate the decision-making process and may be highly specific for certain conditions, such as diurnal fluctuations and l-dopa response in dopa-responsive dystonia, and triggering factors, duration and frequency of attacks in paroxysmal dyskinesia. While the genetic and mutational spectrum across non-parkinsonian movement disorders is broad, certain groups of diseases tend to be associated with specific types of pathogenic variants, such as repeat expansions in many of the ataxias. Some of these pathogenic variants cannot be detected by standard methods, such as panel or exome sequencing, but require the investigation of intronic regions for repeat expansions, such as Friedreich's or FGF14-linked ataxia. With our advancing knowledge of the genetic underpinnings of movement disorders, the incorporation of precise and personalized diagnostic strategies can enhance patient care, prognosis, and the application and development of targeted therapeutic interventions.

Identification of ferroptosis‑associated genes in chronic kidney disease

Ferroptosis serves a pivotal role in developing chronic kidney disease (CKD). The present study aimed to detect and confirm the relevance of potential ferroptosis-related genes in CKD using bioinformatics and experimentation strategies. The original GSE15072 mRNA expression dataset was retrieved from the Gene Expression Omnibus database. Subsequently, the potential differentially expressed genes associated with ferroptosis of CKD were screened using R software. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analyses, correlation analysis and protein-protein interactions (PPI) were performed for differentially expressed ferroptosis-associated genes (DFGs). Lastly, the expression levels of the top nine DFGs were measured in the kidney tissue of Adriamycin-induced CKD rats and healthy controls via reverse transcription-quantitative (RT-q)PCR analysis. Overall, 49 DFGs among 21 patients with CKD and nine healthy controls were identified. GO and KEGG enrichment analyses demonstrated that these DFGs were primarily involved in 'ferroptosis' and 'mitophagy'. PPI findings indicated that these ferroptosis-associated genes interacted with one another. RT-qPCR of CKD tissue from the rat model revealed that STAT3, MAPK14, heat shock protein (HSP)A5, MTOR and solute carrier family 2 member 1 (SLC2A1) mRNA levels in CKD were upregulated. Overall, 49 potential ferroptosis-associated genes of CKD were identified via bioinformatics analyses. STAT3, MAPK14, HSPA5, MTOR and SLC2A1 may influence CKD onset by regulating ferroptosis. The present results add to the existing body of knowledge about CKD and may be useful in the treatment of CKD.

Phenotypic characterisation of paroxysmal dyskinesia in Sphynx cats

OBJECTIVES

The aim of this study was to identify the phenotypic features of a paroxysmal dyskinesia observed in Sphynx cats.

METHODS

The owners of affected Sphynx cats were invited to provide video footage of abnormal episodes for review. Those that demonstrated episodes consistent with paroxysmal dyskinesia were then invited to complete an online questionnaire designed to allow further characterisation.

RESULTS

Ten Sphynx cats were included in the study. All affected cats were <4 years of age at the onset of the episodes (range 0.5-4.0). The episodes had a duration of <5 mins in 9/10 cats (range 0.5-10), while episode frequency was variable between and within individual cats. The episodes were characterised by impaired ambulation due to muscle hypertonicity, most commonly affecting the hips and pelvic limbs (9/10) and shoulders and thoracic limbs (8/10). The head and neck (6/10), tail (5/10), and back and abdomen (3/10) were also involved in some cats. Sudden movement, excitement and stress were identified as possible triggers for the episodes in three cats. Therapeutic intervention was not attempted in 7/10 cases, although two cats were reported to become free of the episodes while receiving acetazolamide. The two cats that were followed beyond 2 years from onset entered spontaneous remission. None of the owners believed that the abnormal episodes had affected the quality of life of their cat.

CONCLUSIONS AND RELEVANCE

The phenotype of paroxysmal dyskinesia in Sphynx cats presented in this study appears to share similarities with paroxysmal kinesigenic dyskinesia described in human classification systems. Some cats appear to achieve episode freedom spontaneously. Subsequent research should focus on evaluating response to treatment and determining an underlying genetic cause.

Paroxysmal dyskinesia and electrodermal volatility: The role of mindfulness, self-compassion and psychophysiological interventions

To date, there are no behavioral or psychophysiological treatment studies on paroxysmal dyskinesia (PD). PD is a group of debilitating movement disorders that present with severe episodes of dystonia, chorea, and/or ballistic like movements. This is a first case report of a 50-year-old male who received behavioral interventions (e.g., mindfulness, CBT, and biofeedback interventions) to manage his PD episodes in tandem with multidisciplinary treatments (e.g., neurology, psychiatry, etc.). The paper primarily discusses the serendipitous observation of galvanic skin response (GSR) elevations and spikes immediately before and after the onset of PD episodes. GSR volatility was noted in wave amplitude and wave morphology. Graphs are presented to illustrate GSR volatility associate with PD episodes and the reduction of GSR volatility in response to behavioral approaches. The discussion highlights the feasibility of using GSR biofeedback as an adjunct to mindfulness and CBT to manage PD as part of a multidisciplinary treatment approach. Peripherally, issues that related to misclassification of somatic symptoms and related disorders (e.g., psychogenic non-epileptic seizures) and aspects of neurocognitive disorders are discussed. The paper reviews neurological findings, MRI, neuropsychological data, and psychiatric assessment to highlight the dilemma clinician's face and clarify behavioral practices to further the management of PD.

Clinical characterisation of a novel paroxysmal dyskinesia in Welsh terrier dogs

Breed specific paroxysmal dyskinesias are increasingly recognised in veterinary medicine. We aimed to characterise the phenomenology, clinical course and prevalence of a previously unreported paroxysmal dyskinesia in the Welsh terrier breed. Clinical records of five Welsh terriers with paroxysmal episodes were reviewed. Additionally, owners of Welsh terriers were invited to complete a questionnaire with the aim of characterising paroxysmal episodes in the wider breed population. Clinical examinations (n = 5) and diagnostic investigations (n = 2) of affected Welsh terriers were within normal limits, apart from mild-moderate ventriculomegaly on cranial magnetic resonance imaging (n = 3). The survey of Welsh terrier owners revealed episodes consistent with a paroxysmal dyskinesia in 41 (22.8%) of 177 respondents. Median age of onset was 59 months. Episodes were predominantly characterised by sustained hypertonicity with periods of limb flexion, abnormal head and body posture, with preserved consciousness. Episode duration ranged from 30 s to 30 min (median, 3 min 30 s), with frequency varying widely between dogs. Affected dogs demonstrated a stable to improving clinical course in most cases. This study investigated a previously unreported paroxysmal dyskinesia in Welsh terriers. Similar clinical signs within the breed were potentially consistent with an inherited cause, worthy of further investigation.

Tics, tremors and other movement disorders in childhood

Movement disorders presenting in childhood include tics, dystonia, chorea, tremor, stereotypy, myoclonus, and parkinsonism, each of which can be part of various clinical syndromes with distinct etiologies.  Some of these conditions are benign and require only reassurance; others are bothersome and require treatment, or may be clues that herald underlying pathology.  Answers lie in the inherent characteristics of the movements themselves, together with the clinical context provided in the history obtained by the examiner.  The aim of this review is to present an overview of the categories of involuntary movements, along with examples of common acquired and genetic causes, and an approach to history-taking, examination, and treatment.

Recommendations for the diagnosis and treatment of paroxysmal kinesigenic dyskinesia: an expert consensus in China

Paroxysmal dyskinesias are a group of neurological diseases characterized by intermittent episodes of involuntary movements with different causes. Paroxysmal kinesigenic dyskinesia (PKD) is the most common type of paroxysmal dyskinesia and can be divided into primary and secondary types based on the etiology. Clinically, PKD is characterized by recurrent and transient attacks of involuntary movements precipitated by a sudden voluntary action. The major cause of primary PKD is genetic abnormalities, and the inheritance pattern of PKD is mainly autosomal-dominant with incomplete penetrance. The proline-rich transmembrane protein 2 (PRRT2) was the first identified causative gene of PKD, accounting for the majority of PKD cases worldwide. An increasing number of studies has revealed the clinical and genetic characteristics, as well as the underlying mechanisms of PKD. By seeking the views of domestic experts, we propose an expert consensus regarding the diagnosis and treatment of PKD to help establish standardized clinical evaluation and therapies for PKD. In this consensus, we review the clinical manifestations, etiology, clinical diagnostic criteria and therapeutic recommendations for PKD, and results of genetic analyses in PKD patients performed in domestic hospitals.

Disruption of gray matter morphological networks in patients with paroxysmal kinesigenic dyskinesia

This study explores the topological properties of brain gray matter (GM) networks in patients with paroxysmal kinesigenic dyskinesia (PKD) and asks whether GM network features have potential diagnostic value. We used 3D T1-weighted magnetic resonance imaging and graph theoretical approaches to investigate the topological organization of GM morphological networks in 87 PKD patients and 115 age- and sex-matched healthy controls. We applied a support vector machine to GM morphological network matrices to classify PKD patients versus healthy controls. Compared with the HC group, the GM morphological networks of PKD patients showed significant abnormalities at the global level, including an increase in characteristic path length (Lp) and decreases in local efficiency (Eloc ), clustering coefficient (Cp), normalized clustering coefficient (γ), and small-worldness (σ). The decrease in Cp was significantly correlated with disease duration and age of onset. The GM morphological networks of PKD patients also showed significant changes in nodal topological characteristics, mainly in the basal ganglia-thalamus circuitry, default-mode network and central executive network. Finally, we used the GM morphological network matrices to classify individuals as PKD patients versus healthy controls, achieving 87.8% accuracy. Overall, this study demonstrated disruption of GM morphological networks in PKD, which might extend our understanding of the pathophysiology of PKD; further, GM morphological network matrices might have the potential to serve as network neuroimaging biomarkers for the diagnosis of PKD.

Phenotypic characterization of PIGN-associated paroxysmal dyskinesia in Soft-coated wheaten terriers and preliminary response to acetazolamide therapy

A hereditary movement disorder in Soft coated wheaten terriers (SCWT) has been associated with a mutation in PIGN which encodes an enzyme involved in synthesis of glycosylphosphatidylinositol (GPI). The objective of this study was to describe and classify the clinical phenotype and assess therapeutic response. Twenty-five SCWT and related dogs homozygous for PIGN:c.398C>T with paroxysmal dyskinesia were available for inclusion. Medical records and video recordings of 17 dogs were evaluated in a retrospective case series. Affected dogs had episodes of involuntary, hyperkinetic movements and dystonia. Median age of onset was 2.5 years. A typical episode consisted of rapid, irregular hyperflexion and extension of the pelvic limbs with some degree of truncal dystonia. A mild episode consisted of spontaneous flexion of one pelvic limb while walking which could resemble a lameness. Episodes lasted several minutes to several hours and occurred up to 10 times/day or more. They were not associated with exercise or fasting but were sometimes triggered by excitement or stress. Acetazolamide therapy improved nine of 11 dogs, in seven cases abolishing episodes. Five of 17 dogs treated with other agents had mild improvement with clonazepam (n = 2), levetiracetam (n = 1), or phenobarbital (n = 2). Paroxysmal dyskinesias must be differentiated from seizure disorders since they often respond to different therapies. The SCWT phenotype consisted predominantly of hyperkinesia, and can respond dramatically to acetazolamide. GPI anchors proteins to the cell surface including carbonic anhydrase IV which modulates synaptic pH in the brain. Altered activity of this enzyme may be the target of acetazolamide therapy.

Shedding light on thyroid hormone disorders and Parkinson disease pathology: mechanisms and risk factors

Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons. Dopaminergic system is interconnected with the hypothalamic-pituitary-thyroid axis. Dopamine (DA) upregulates thyrotropin releasing hormone (TRH) while downregulating thyroid stimulating hormone (TSH) and thyroid hormones. Moreover, TRH stimulates DA release. PD is associated with impaired regulation of TSH and thyroid hormones (TH) levels, which in turn associate with severity and different subtypes of PD, while levodopa and bromocriptine treatment can interfere with hypothalamic-pituitary-thyroid axis. Thyroid disturbances, including hypothyroidism, Hashimoto's thyroiditis (HT), hyperthyroidism and Graves' disease (GD) not only increase the risk of PD but also share some clinical signs with PD. Also, several genes including RASD2, WSB1, MAPT, GIRK2, LRRK2 and gene products like neurotensin and NOX/DUOX affect the risk for both PD and thyroid disease. Hypothyroidism is associated with obesity, hypercholesterolemia, anemia and altered cerebral blood flow which are associated with PD pathology. Herein we provide a comprehensive view on the association between PD and thyroid hormones regulation and dysregulations, hoping to provide new avenues towards targeted treatment of PD. We performed a comprehensive search in literature using Pubmed and Scopus, yielding to a total number of 36 original articles that had addressed the association between thyroid hormone disorders and PD.

Neural Mechanisms of Paroxysmal Kinesigenic Dyskinesia: Insights from Neuroimaging

Paroxysmal kinesigenic dyskinesia (PKD) is a rare movement disorder of the nervous system, and little is known about its pathogenesis. Currently, the diagnosis of PKD is primarily based on clinical manifestations, with little objective evidence. Neuroimaging has been used to explore the pathological changes in cerebral structure and function associated with PKD. The current review highlights recent advances in neuroimaging to provide a better understanding of the neural mechanisms and early diagnosis of this disorder. Several studies utilizing single-photon emission computed tomography (CT), positron emission tomography, and structural and functional magnetic resonance imaging have found significant localized abnormalities in the caudate nucleus, putamen, pallidum, thalamus, and frontoparietal cortex in PKD patients. These studies have also revealed alterations in interhemispheric functional connectivity between the brain regions of bilateral cerebral hemispheres such as the putamen, primary motor cortex, supplementary motor area, dorsal lateral prefrontal cortex, and primary somatosensory cortex in these patients. In addition, proline-rich transmembrane protein 2 gene mutations can affect the functional organization of the brain in PKD. These results suggest that the neural mechanisms of PKD are associated with the disruption of both structural and/or functional properties in basal ganglia-thalamo-cortical circuitry and interhemispheric functional connectivity. PKD can be considered a circuitry/network disorder and is not restricted to localized structural and/or functional abnormalities. Multimodal neuroimaging combined with gene analysis can provide additional valuable information for a better understanding of the pathogenesis and early diagnosis of this disorder.

Treatment of Secondary Chorea: A Review of the Current Literature

Background

Chorea consists of involuntary movements affecting the limbs, trunk, neck or face, that can move from one body part to another. Chorea is conceptualized as being "primary" when it is attributed to Huntington's disease (HD) or other genetic etiologies, or "secondary" when it is related to infectious, pharmacologic, metabolic, autoimmune disorders, or paraneoplastic syndromes. The mainstay of the secondary chorea management is treating the underlying causative disorder; here we review the literature regarding secondary chorea. We also discuss the management of several non-HD genetic diseases in which chorea can be a feature, where metabolic targets may be amenable to intervention and chorea reduction.

Methods

A PubMed literature search was performed for articles relating to chorea and its medical and surgical management. We reviewed the articles and cross-references of pertinent articles to assess the current clinical practice, expert opinion, and evidence-based medicine to synthesize recommendations for the management of secondary chorea.

Results

There are very few double-blind randomized controlled trials assessing chorea treatments regardless of etiology. Most recommendations are based on small open-label studies, case reports, and expert opinion.

Discussion

Treatment of secondary chorea is currently based on expert opinion, clinical experience, and small case studies, with limited evidence-based medical data. When chorea is secondary to an underlying infection, medication, metabolic abnormality, autoimmune process, or paraneoplastic illness, the movements typically resolve following treatment of the underlying disease. Tardive dyskinesia is most rigorously studied secondary chorea with the best evidence-based medicine treatment guidelines recommending the use of pre-synaptic dopamine-depleting agents. Even though there is an insufficient pool of EBM, small clinical trials, case reports, and expert opinion are valuable for guiding treatment and improving the quality of life for patients with chorea.

Highlights

There is a dearth of well-controlled studies regarding the treatment of chorea. Expert opinion and clinical experiences are fundamental in guiding chorea management and determining successful treatment. In general, secondary chorea improves with treating the underlying medical abnormality; treatments include antibiotics, antivirals, immunosuppression, dopamine depleting agents, chelation, and supportive care.

Clinical and Genetic Overview of Paroxysmal Movement Disorders and Episodic Ataxias

Paroxysmal movement disorders (PMDs) are rare neurological diseases typically manifesting with intermittent attacks of abnormal involuntary movements. Two main categories of PMDs are recognized based on the phenomenology: Paroxysmal dyskinesias (PxDs) are characterized by transient episodes hyperkinetic movement disorders, while attacks of cerebellar dysfunction are the hallmark of episodic ataxias (EAs). From an etiological point of view, both primary (genetic) and secondary (acquired) causes of PMDs are known. Recognition and diagnosis of PMDs is based on personal and familial medical history, physical examination, detailed reconstruction of ictal phenomenology, neuroimaging, and genetic analysis. Neurophysiological or laboratory tests are reserved for selected cases. Genetic knowledge of PMDs has been largely incremented by the advent of next generation sequencing (NGS) methodologies. The wide number of genes involved in the pathogenesis of PMDs reflects a high complexity of molecular bases of neurotransmission in cerebellar and basal ganglia circuits. In consideration of the broad genetic and phenotypic heterogeneity, a NGS approach by targeted panel for movement disorders, clinical or whole exome sequencing should be preferred, whenever possible, to a single gene approach, in order to increase diagnostic rate. This review is focused on clinical and genetic features of PMDs with the aim to (1) help clinicians to recognize, diagnose and treat patients with PMDs as well as to (2) provide an overview of genes and molecular mechanisms underlying these intriguing neurogenetic disorders.

Companion animal models of neurological disease

Clinical translation of novel therapeutics that improve the survival and quality of life of patients with neurological disease remains a challenge, with many investigational drug and device candidates failing in advanced stage clinical trials. Naturally occurring inherited and acquired neurological diseases, such as epilepsy, inborn errors of metabolism, brain tumors, spinal cord injury, and stroke occur frequently in companion animals, and many of these share epidemiologic, pathophysiologic and clinical features with their human counterparts. As companion animals have a relatively abbreviated lifespan and genetic background, are immunocompetent, share their environment with human caregivers, and can be clinically managed using techniques and tools similar to those used in humans, they have tremendous potential for increasing the predictive value of preclinical drug and device studies. Here, we review comparative features of spontaneous neurological diseases in companion animals with an emphasis on neuroimaging methods and features, illustrate their historical use in translational studies, and discuss inherent limitations associated with each disease model. Integration of companion animals with naturally occurring disease into preclinical studies can complement and expand the knowledge gained from studies in other animal models, accelerate or improve the manner in which research is translated to the human clinic, and ultimately generate discoveries that will benefit the health of humans and animals.

Treatment of Chorea in Childhood

Chorea is a movement disorder characterized by ongoing random-appearing sequences of discrete involuntary movements or movement fragments. Chorea results from dysfunction of the complex neuronal networks that interconnect the basal ganglia, thalamus, and related frontal lobe cortical areas. The complexity of basal ganglia circuitry and vulnerability of those circuits to injury explains why chorea results from a wide variety of conditions. Because etiology-specific treatments or effective symptomatic treatments are available for causes of chorea, defining the underlying disease is important. The treatment of chorea can be considered in three main categories: (1) terminating or modifying exposure to the causative agent, (2) symptomatic treatment of chorea, and (3) treatment targeting the underlying etiology. Symptomatic treatment decision of chorea should be based on the functional impact on the child caused by chorea itself. There have been no reported randomized, placebo-controlled trials of symptomatic treatment for chorea in childhood. Thus the recommendations are based on clinical experience, case reports, expert opinions, and small comparative studies. Better knowledge of mechanisms underlying childhood chorea will provide more etiology-based treatments in the future.

The spectrum of paroxysmal dyskinesias

Paroxysmal dyskinesias (PxD) comprise a group of heterogeneous syndromes characterized by recurrent attacks of mainly dystonia and/or chorea, without loss of consciousness. PxD have been classified according to their triggers and duration as paroxysmal kinesigenic dyskinesia, paroxysmal nonkinesigenic dyskinesia and paroxysmal exertion-induced dyskinesia. Of note, the spectrum of genetic and nongenetic conditions underlying PxD is continuously increasing, but not always a phenotype–etiology correlation exists. This creates a challenge in the diagnostic work-up, increased by the fact that most of these episodes are unwitnessed. Furthermore, other paroxysmal disorders, included those of psychogenic origin, should be considered in the differential diagnosis. In this review, some key points for the diagnosis are provided, as well as the appropriate treatment and future approaches discussed.

Paroxysmal Movement Disorders: Recent Advances

PURPOSE OF REVIEW

Recent advancements in next-generation sequencing (NGS) have enabled techniques such as whole exome sequencing (WES) and whole genome sequencing (WGS) to be used to study paroxysmal movement disorders (PMDs). This review summarizes how the recent genetic advances have altered our understanding of the pathophysiology and treatment of the PMDs. Recently described disease entities are also discussed.

RECENT FINDINGS

With the recognition of the phenotypic and genotypic heterogeneity that occurs amongst the PMDs, an increasing number of gene mutations are now implicated to cause the disorders. PMDs can also occur as part of a complex phenotype. The increasing complexity of PMDs challenges the way we view and classify them. The identification of new causative genes and their genotype-phenotype correlation will shed more light on the underlying pathophysiology and will facilitate development of genetic testing guidelines and identification of novel drug targets for PMDs.

Restless Legs Syndrome in NKX2-1-related chorea: An expansion of the disease spectrum

BACKGROUND

Molecular technologies are expanding our knowledge about genetic variability underlying early-onset non-progressive choreic syndromes. Focusing on NKX2-1-related chorea, the clinical phenotype and sleep related disorders have been only partially characterized.

METHODS

We propose a retrospective and longitudinal observational study in 7 patients with non-progressive chorea due to NKX2-1 mutations. In all subjects sleep and awake EEG, brain MRI with study of pituitary gland, chest X-rays, endocrinological investigations were performed. Movement disorders, pattern of sleep and related disorders were investigated using structured clinical evaluation and several validated questionnaires.

RESULTS

In patients carrying NKX2-1 mutations, chorea was mainly distributed in the upper limbs and tended to improve with age. All patients presented clinical or subclinical hypothyroidism and delayed motor milestones. Three subjects had symptoms consistent with Restless Legs Syndrome (RLS) that improved with Levodopa.

CONCLUSIONS

Patients with NKX2-1 gene mutations should be investigated for RLS, which, similarly to chorea, can sometimes be ameliorated by Levodopa.

Paroxysmal movement disorders: Recent advances and proposal of a classification system

The increasing recognition of the phenotypic and genotypic heterogeneity that exists amongst the paroxysmal movement disorders (PMDs) is challenging the way these disorders have been traditionally classified. The present review aims to summarize how recent genetic advances have influenced our understanding of the nosology, pathophysiology and treatment strategies of paroxysmal movement disorders. We propose classifying PMDs using a system that would combine both phenotype and genotype information to allow these disorders to be better categorized and studied. In the era of next generation sequencing, the use of a standardized algorithm and employment of selective genetic screening will lead to greater diagnostic certainty and targeted therapeutics for the patients.

Paroxysmal Dyskinesias in a PRRT2 Mutation Carrier

Background

Paroxysmal movement disorders are rare and heterogeneous genetic conditions characterized by the recurrence of transient involuntary movements.

Phenomenology Shown

The phenomenology of a paroxysmal kinesigenic dyskinesia in a young professional athlete.

Educational Value

Providing basic clinical and genetic elements for the early recognition and diagnosis of a rare movement disorder.

Paroxysmal Dyskinesias

Paroxysmal dyskinesias (PD) are hyperkinetic movement disorders where patients usually retain consciousness. Paroxysmal dyskinesias can be kinesigenic (PKD), nonkinesigenic (PNKD), and exercise induced (PED). These are usually differentiated from each other based on their phenotypic and genotypic characteristics. Genetic causes of PD are continuing to be discovered. Genes found to be involved in the pathogenesis of PD include MR-1, PRRT2, SLC2A1, and KCNMA1. The differential diagnosis is broad as PDs can mimic psychogenic events, seizure, or other movement disorders. This review also includes secondary causes of PDs, which can range from infections, metabolic, structural malformations to malignancies. Treatment is usually based on the correct identification of type of PD. PKD responds well to antiepileptic medications, whereas PNKD and PED respond to avoidance of triggers and exercise, respectively. In this article, we review the classification, clinical features, genetics, differential diagnosis, and management of PD.

Precipitation and inhibition of seizures in focal epilepsies

INTRODUCTION

There is growing awareness that reflex epileptic seizures offer unique insight into natural seizure generation in humans. In the last years, focus has mostly been on reflex seizures in generalized epilepsies whereas a comprehensive review of their role in focal epilepsies has been missing. Areas covered: This paper reviews reflex seizures strictly in focal epilepsies, not including focal reflex seizures in system epilepsies that also exist. They were categorized according to their triggers which can be sensory or cognitive, simple or complex. Numerous diverse conditions exist some of which are much better investigated than others. They required separate individual literature search in PubMed. Where recent review papers exist, it refers to these, but several conditions have never been reviewed, and here it refer to and discusses original reports. Miscellaneous case reports were only exceptionally included when they contributed aspects otherwise missing. Expert commentary: Research on focal reflex seizures with advanced methods of imaging and neurophysiology to elucidate mechanisms of focal ictogenesis will probably be rapidly increasing and will soon provide much new insight. Sensory and cognitive inhibition, i.e. the counterpart of reflex ictogenesis, is promising but needs more structured and controlled research to establish robust therapeutic approaches.

Paroxysmal Dyskinesia in Border Terriers: Clinical, Epidemiological, and Genetic Investigations

Background

In the last decade, a disorder characterized by episodes of involuntary movements and dystonia has been recognized in Border Terriers.

Objectives

To define clinical features of paroxysmal dyskinesia (PD) in a large number of Border Terriers and to study the genetics of the disease.

Animals

110 affected and 128 unaffected client‐owned Border Terriers.

Methods

A questionnaire regarding clinical characteristics of PD was designed at Utrecht University and the University of Helsinki. Thirty‐five affected Border Terriers underwent physical examination and blood testing (hematology and clinical biochemistry). Diagnostic imaging of the brain was performed in 17 affected dogs and electroencephalograms (EEG) between episodes were obtained in 10 affected dogs. A genomewide association study (GWAS) was performed with DNA of 110 affected and 128 unaffected dogs.

Results

One hundred forty‐seven questionnaires were included in the study. The most characteristic signs during episodes were dystonia, muscle fasciculations, and falling over. The majority of owners believed that their dogs remained conscious during the episodes. A beneficial effect of anti‐epileptic therapy was observed in 29 of 43 dogs. Fifteen owners changed their dogs’ diet to a hypoallergenic, gluten‐free diet, and all reported reasonable to good improvement of signs. Clinical examinations and diagnostic test results were unremarkable. The GWAS did not identify significantly associated chromosome regions.

Conclusions and Clinical Importance

The survey results and EEG studies provided further evidence that the observed syndrome is a PD rather than epilepsy. Failure to achieve conclusive results by GWAS indicates that inheritance of PD in Border Terriers probably is complex.

Treatment options for chorea

INTRODUCTION

Chorea is defined as jerk-like movements that move randomly from one body part to another. It is due to a variety of disorders and although current symptomatic therapy is quite effective there are few etiology- or pathogenesis-targeted therapies. The aim of this review is to summarize our own experience and published evidence in the treatment of chorea. Areas covered: After evaluating current guidelines and clinical practices for chorea of all etiologies, PubMed was searched for the most recent clinical trials and reviews using the term 'chorea' cross referenced with specific drug names. Expert commentary: Inhibitors of presynaptic vesicular monoamine transporter type 2 (VMAT2) that cause striatal dopamine depletion, such as tetrabenazine, deutetrabenazine, and valbenazine, are considered the treatment of choice in patients with chorea. Some clinicians also use dopamine receptor blockers (e.g. antipsychotics) and other drugs, including anti-epileptics and anti-glutamatargics. 'Dopamine stabilizers' such as pridopidine and other experimental drugs are currently being investigated in the treatment of chorea. Deep brain stimulation is usually reserved for patients with disabling chorea despite optimal medical therapy.

Secondary paroxysmal dyskinesia in multiple sclerosis: Clinical–radiological features and treatment. Case report of seven patients

Secondary paroxysmal dyskinesias (SPDs) are short, episodic, and recurrent movement disorders, classically related to multiple sclerosis (MS). Carbamazepine is effective, but with risk of adverse reactions. We identified 7 patients with SPD among 457 MS patients (1.53%). SPD occurred in face ( n = 1), leg ( n = 2), or arm +leg ( n = 4) several times during the day. Magnetic resonance imaging (MRI) showed new or enhancing lesions in thalamus ( n = 1), mesencephalic tegmentum ( n = 1), and cerebellar peduncles ( n = 5). Patients were treated with clonazepam and then acetazolamide ( n = 1), acetazolamide ( n = 5), or levetiracetam ( n = 1) with response within hours (acetazolamide) to days (levetiracetam). No recurrences or adverse events were reported after a median follow-up of 33 months.

Ataxia in children: early recognition and clinical evaluation

Background

Ataxia is a sign of different disorders involving any level of the nervous system and consisting of impaired coordination of movement and balance. It is mainly caused by dysfunction of the complex circuitry connecting the basal ganglia, cerebellum and cerebral cortex.

A careful history, physical examination and some characteristic maneuvers are useful for the diagnosis of ataxia. Some of the causes of ataxia point toward a benign course, but some cases of ataxia can be severe and particularly frightening.

Methods

Here, we describe the primary clinical ways of detecting ataxia, a sign not easily recognizable in children. We also report on the main disorders that cause ataxia in children.

Results

The causal events are distinguished and reported according to the course of the disorder: acute, intermittent, chronic-non-progressive and chronic-progressive.

Conclusions

Molecular research in the field of ataxia in children is rapidly expanding; on the contrary no similar results have been attained in the field of the treatment since most of the congenital forms remain fully untreatable. Rapid recognition and clinical evaluation of ataxia in children remains of great relevance for therapeutic results and prognostic counseling.

Recurrent Ataxia in Children and Adolescents

Background: Recurrent ataxia is encountered infrequently in clinical pediatric neurology practise and presents with diagnostic challenges. It is caused by several disorders. Our aims were to describe the epidemiology and clinical features in children with recurrent ataxia. Materials and Methods: A retrospective review was undertaken in 185 children with chronic ataxia, who presented during 1991 to 2008. Several databases were searched to ensure optimum ascertainment. Patients with brain tumors or isolated disorders of the peripheral nerves or vestibular system were excluded. Results: Recurrent ataxia was reported in 21 patients. Their age range was between 6 and 32.75 years (males=12). The crude period prevalence rate for the 18-year study period was 7.44/100,000. Eight patients had episodic ataxia and seven had inflammatory and metabolic disorders. In the rest the etiology was unknown. Many patients presented with ataxia, dizziness, and vertigo. The frequency and duration of the ataxic episodes varied from several per day to one every few months. Other clinical features included developmental delay and seizures. Neuroimaging in episodic ataxia was normal and abnormal in inflammatory or metabolic disorders. Acetazolamide provided symptomatic relief in patients with episodic ataxia, while steroids were beneficial in patients with an inflammatory etiology. One child with a metabolic disorder died. Conclusions: Recurrent ataxia is an uncommon presentation in children and mortality is rare. Genetic, metabolic, and inflammatory disorders should be considered in these patients. Neuroimaging is essential. Acetazolamide in selected patients provides good symptomatic relief.

A homozygous PIGN missense mutation in Soft-Coated Wheaten Terriers with a canine paroxysmal dyskinesia

Hereditary paroxysmal dyskinesias (PxD) are a heterogeneous group of movement disorders classified by frequency, duration, and triggers of the episodes. A young-adult onset canine PxD has segregated as an autosomal recessive trait in Soft-Coated Wheaten Terriers. The medical records and videos of episodes from 25 affected dogs were reviewed. The episodes of hyperkinesia and dystonia lasted from several minutes to several hours and could occur as often as >10/day. They were not associated with strenuous exercise or fasting but were sometimes triggered by excitement. The canine PxD phenotype most closely resembled paroxysmal non-kinesigenic dyskinesia (PNKD) of humans. Whole genome sequences were generated with DNA from 2 affected dogs and analyzed in comparison to 100 control canid whole genome sequences. The two whole genome sequences from dogs with PxD had a rare homozygous PIGN:c.398C > T transition, which predicted the substitution of an isoleucine for a highly conserved threonine in the encoded enzyme. All 25 PxD-affected dogs were PIGN:c.398T allele homozygotes, whereas there were no c.398T homozygotes among 1185 genotyped dogs without known histories of PxD. PIGN encodes an enzyme involved in the biosynthesis of glycosylphosphatidylinositol (GPI), which anchors a variety of proteins including CD59 to the cell surface. Flow cytometry of PIGN-knockout HEK239 cells expressing recombinant human PIGN with the c.398T variant showed reduced CD59 expression. Mutations in human PIGN have been associated with multiple congenital anomalies-hypotonia-seizures syndrome-1 (MCAHS1). Movement disorders can be a part of MCAHS1, but this is the first PxD associated with altered GPI anchor function.

Medical treatment of dystonia

Therapeutic strategies in dystonia have evolved considerably in the past few decades. Three major treatment modalities include oral medications, botulinum toxin injections and surgical therapies, particularly deep brain stimulation. Although there has been a tremendous interest in the later two modalities, there are relatively few recent reviews of oral treatment. We review the medical treatment of dystonia, focusing on three major neurotransmitter systems: cholinergic, GABAergic and dopaminergic. We also provide a practical guide to medication selection, therapeutic strategy and unmet needs.

Movement disorders in multiple sclerosis and their treatment

Hyperkinetic movement disorders such as tremors are not uncommon in patients with multiple sclerosis (MS). The classical feature is intention tremor, whereas rest tremors appear not to occur. Treatment is mainly invasive, with options of Gamma Knife surgery, thalamotomy or deep brain stimulation depending on individual circumstances. Deep brain stimulation is the only option for patients who require a bilateral intervention. All treatment recommendations have only low evidence. Tremors can also be cured spontaneously by a subsequent strategic MS lesion. Paroxysmal dyskinesias are rarer than tremors. The rarest MS movement disorder is symptomatic paroxysmal choreoathetosis, tonic spasms or ‘brain stem fits’; attacks are short but frequent, up to 200 per day and generally respond well to carbamazepine.

Paroxysmal Nonepileptic Events in Glut1 Deficiency

Movement disorders are a major feature of Glut1 deficiency. As recently identified in adults with paroxysmal exercise‐induced dystonia, similar events were reported in pediatric Glut1 deficiency. In a case series, parent videos of regular motor state and paroxysmal events were requested from children with Glut1 deficiency on clinical follow‐up. A questionnaire was sent out to 60 families. Videos of nonparoxysmal/paroxysmal states in 3 children illustrated the ataxic‐dystonic, choreatiform, and dyskinetic‐dystonic nature of paroxysmal events. Fifty‐six evaluated questionnaires confirmed this observation in 73% of patients. Events appeared to increase with age, were triggered by low ketosis, sleep deprivation, and physical exercise, and unrelated to sex, hypoglycorrhachia, SLC2A1 mutations, or type of ketogenic diet. We conclude that paroxysmal events are a major clinical feature in Glut1 deficieny, linking the pediatric disease to adult Glut1D‐associated exercise‐induced paroxysmal dyskinesias.

Paroxysmal Dyskinesia in Norwich Terrier Dogs

Background

Episodic muscular hypertonicity in Norwich terrier dogs was first reported in a brief communication in 1984. Since then, the condition has remained poorly characterized.

Objectives

The aims of this study were to characterize the phenomenology, clinical course, and family history of paroxysmal dyskinesia in the Norwich terrier and to estimate its prevalence in the United Kingdom.

Methods

The owners of Norwich terrier dogs born since January 1, 2000 were invited to complete a specifically designed questionnaire aimed at identifying affected and unaffected dogs and investigating the clinical characteristics of this paroxysmal dyskinesia. Pedigrees were collected and reviewed.

Results

The questionnaire was returned for 198 Norwich terrier dogs. Of these, 26 (13%) were classified as affected by paroxysmal dyskinesia after revision of the questionnaires and after obtaining videos of the episodes, veterinary medical records, and telephone interviews with the owners. All dogs were neurologically normal between episodes. No significant abnormalities were detected on diagnostic investigations. Mean age at the first episode was 3 years. The episodes were characterized by sustained muscular hypertonicity in the pelvic limbs, lumbar region, and thoracic limbs, impairing posture and locomotion without loss of consciousness. Episode frequency varied both between and within individuals. Stress, anxiety, excitement, and variation in daily routine were recognized as episode triggers in 13 dogs. Episode duration generally was from 2 to 5 minutes (range, from < 2 to 30 minutes). The majority of affected dogs were related.

Conclusions

Paroxysmal dyskinesia segregates in an extended pedigree of Norwich terrier dogs and thus is potentially an inherited disorder in this breed.

Phenotypic insights into ADCY5-associated disease

Background

Adenylyl cyclase 5 (ADCY5) mutations is associated with heterogenous syndromes: familial dyskinesia and facial myokymia; paroxysmal chorea and dystonia; autosomal‐dominant chorea and dystonia; and benign hereditary chorea. We provide detailed clinical data on 7 patients from six new kindreds with mutations in the ADCY5 gene, in order to expand and define the phenotypic spectrum of ADCY5 mutations.

Methods

In 5 of the 7 patients, followed over a period of 9 to 32 years, ADCY5 was sequenced by Sanger sequencing. The other 2 unrelated patients participated in studies for undiagnosed pediatric hyperkinetic movement disorders and underwent whole‐exome sequencing.

Results

Five patients had the previously reported p.R418W ADCY5 mutation; we also identified two novel mutations at p.R418G and p.R418Q. All patients presented with motor milestone delay, infantile‐onset action‐induced generalized choreoathetosis, dystonia, or myoclonus, with episodic exacerbations during drowsiness being a characteristic feature. Axial hypotonia, impaired upward saccades, and intellectual disability were variable features. The p.R418G and p.R418Q mutation patients had a milder phenotype. Six of seven patients had mild functional gain with clonazepam or clobazam. One patient had bilateral globus pallidal DBS at the age of 33 with marked reduction in dyskinesia, which resulted in mild functional improvement.

Conclusion

We further delineate the clinical features of ADCY5 gene mutations and illustrate its wide phenotypic expression. We describe mild improvement after treatment with clonazepam, clobazam, and bilateral pallidal DBS. ADCY5‐associated dyskinesia may be under‐recognized, and its diagnosis has important prognostic, genetic, and therapeutic implications. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society

Primary and secondary ataxias

PURPOSE OF REVIEW

This article discusses recent advances in the understanding of clinical and genetic aspects of primary ataxias, including congenital, autosomal recessive, autosomal dominant, episodic, X-linked, and mitochondrial ataxias, as well as idiopathic degenerative and secondary ataxias.

RECENT FINDINGS

Many important observations have been published in recent years in connection with primary ataxias, particularly new loci and genes. The most commonly inherited ataxias may present with typical and atypical phenotypes. In the group of idiopathic degenerative ataxias, genes have been found in patients with multiple system atrophy type C. Secondary ataxias represent an important group of sporadic, cerebellar, and afferent/sensory ataxias.

SUMMARY

Knowledge of primary ataxias has been growing rapidly in recent years. Here we review different forms of primary ataxia, including inherited forms, which are subdivided into congenital, autosomal recessive cerebellar ataxias, autosomal dominant cerebellar ataxias, episodic ataxias, X-linked ataxias, and mitochondrial ataxias, as well as sporadic ataxias and idiopathic degenerative ataxias. Secondary or acquired ataxias are also reviewed and the most common causes are discussed.