Chorea

A mother and her daughter carrying a pathogenic expansion of the HTT gene with a phenotype encompassing motor neuron disease and Huntington's disease

Recently, pathogenic expansions (range 40-64 CAG repeats) in the HTT gene have been found in patients diagnosed with pure frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). We report a mother with Huntington's disease (HD) associated with motor neuron disease (MND) signs and her daughter suffering from ALS with subtle signs of HD, both carrying a pathogenic allele of the HTT gene (i.e., >39 repeats). The co-occurrence of MND and chorea has been reported in previous cases. Subjects showing both ALS and HD signs and carrying HTT pathogenic expansions in two generations of the same kindred have never been reported so far. The study of the overlap of disease mechanisms at the cellular level between TDP-43 and Huntingtin is relevant in an era offering promising strategies of targeted treatments in neurodegenerative disorders.

Assessment of Postural Control in Children with Movement Disorders by Means of a New Technological Tool: A Pilot Study

Considering the variability and heterogeneity of motor impairment in children with Movement Disorders (MDs), the assessment of postural control becomes essential. For its assessment, only a few tools objectively quantify and recognize the difference among children with MDs. In this study, we use the Virtual Reality Rehabilitation System (VRRS) for assessing the postural control in children with MD. Furthermore, 16 children (mean age 10.68 ± 3.62 years, range 4.29-18.22 years) were tested with VRRS by using a stabilometric balance platform. Postural parameters, related to the movements of the Centre of Pressure (COP), were collected and analyzed. Three different MD groups were identified according to the prevalent MD: dystonia, chorea and chorea-dystonia. Statistical analyses tested the differences among MD groups in the VRRS-derived COP variables. The mean distance, root mean square, excursion, velocity and frequency values of the dystonia group showed significant differences (p < 0.05) between the chorea group and the chorea-dystonia group. Technology provides quantitative data to support clinical assessment: in this case, the VRRS detected differences among the MD patterns, identifying specific group features. This tool could be useful also for monitoring the longitudinal trajectories and detecting post-treatment changes.

Movement disorders of the mouth: a review of the common phenomenologies

Movement disorders of the mouth encompass a spectrum of hyperactive movements involving the muscles of the orofacial complex. They are rare conditions and are described in the literature primarily in case reports originating from neurologists, psychiatrists, and the dental community. The focus of this review is to provide a phenomenological description of different oral motor disorders including oromandibular dystonia, orofacial dyskinesia and orolingual tremor, and to offer management strategies for optimal treatment based on the current literature. A literature search of full text studies using PubMed/Medline and Cochrane library combined with a manual search of the reference lists was conducted until June 2021. Results from this search included meta-analyses, systematic reviews, reviews, clinical studies, case series, and case reports published by neurologists, psychiatrists, dentists and oral and maxillofacial surgeons. Data garnered from these sources were used to provide an overview of most commonly encountered movement disorders of the mouth, aiding physicians in recognizing these rare conditions and in initiating appropriate therapy.

Autoimmune and Paraneoplastic Chorea: A Review of the Literature

Autoimmune chorea syndromes represent a vast array of paraneoplastic, parainfectious and idiopathic disorders. It is increasingly apparent that familiarity with these disorders is critically important, as they may be treatable or may be part of a syndrome requiring further work-up and monitoring. These disorders are mediated by an aberrant immunologic attack with resultant neuronal dysfunction, manifesting as chorea. These conditions are typically accompanied by other neurologic or systemic manifestations. In this review we outline the clinical features, epidemiologic factors, and delineate the specific antibodies associated with each of these autoimmune mediated disorders. We highlight up to date information regarding this heterogeneous group of disorders, including a discussion of parainfectious Sydenham's chorea; paraneoplastic syndromes associated with CRMP-5 (collapsin response mediated protein-5/CV2) and ANNA-1 (antineuronal nuclear antibody / Hu) antibodies, in addition to neuronal antibody-associated disorders including anti-NMDAR, LGI1 (leucine-rich glioma inactivated-1) and CASPR2 (contactin associated protein-2). We discuss the more recently described entities of IgLON5, which has evidence of both immunologic and degenerative pathophysiology, in addition to PDE-10A antibody-associated chorea. We also outline chorea secondary to systemic diseases including Systemic Lupus Erythematosus (SLE) and Primary Antiphospholipid Syndrome (PAPS). We provide a framework for diagnosis and treatment.

Combining Literature Review With a Ground Truth Approach for Diagnosing Huntington's Disease Phenocopy

One percent of patients with a Huntington's disease (HD) phenotype do not have the Huntington (HTT) gene mutation. These are known as HD phenocopies. Their diagnosis is still a challenge. Our objective is to provide a diagnostic approach to HD phenocopies based on medical expertise and a review of the literature. We employed two complementary approaches sequentially: a review of the literature and two surveys analyzing the daily clinical practice of physicians who are experts in movement disorders. The review of the literature was conducted from 1993 to 2020, by extracting articles about chorea or HD-like disorders from the database Pubmed, yielding 51 articles, and analyzing 20 articles in depth to establish the surveys. Twenty-eight physicians responded to the first survey exploring the red flags suggestive of specific disease entities. Thirty-three physicians completed the second survey which asked for the classification of paraclinical tests according to their diagnostic significance. The analysis of the results of the second survey used four different clustering algorithms and the density-based clustering algorithm DBSCAN to classify the paraclinical tests into 1st, 2nd, and 3rd-line recommendations. In addition, we included suggestions from members of the European Reference Network-Rare Neurological Diseases (ERN-RND Chorea &amp; Huntington disease group). Finally, we propose guidance that integrate the detection of clinical red flags with a classification of paraclinical testing options to improve the diagnosis of HD phenocopies.

One Side of the Story; Clues to Etiology in Patients with Asymmetric Chorea

Background:

Chorea can be due to a large number of etiologies. Unilateral chorea is classically related to a contralateral structural lesion, e.g. of the putamen or subthalamic nucleus, however, based upon personal impressions, we have observed that systemic disease, in particular metabolic or autoimmune conditions, can also lead to a unilateral or markedly asymmetric presentations. We sought to investigate this impression by reviewing the literature.

Methods:

A PubMed search was conducted using the terms asymmetric” AND “chorea” OR “hemichorea” OR “unilateral” AND “chorea” OR “monochorea” OR “right greater than left” AND “chorea” OR “left greater than right” AND “chorea” OR “right more than left” AND “chorea” OR “left more than right” AND “chorea” as well as “hemiballismus” NOT “stroke” NOT “infarct” NOT “dyskinesia. A total of 243 sources were felt to meet criteria and were reviewed.

Results:

The most common etiology of reported hemi- or asymmetric chorea was diabetic non-ketotic hyperglycemic hemichorea/hemiballismus. Other common diagnoses were Sydenham’s disease, antiphospholipid syndrome and drug-induced chorea. The vast majority of patients with hemi- or asymmetric chorea had acquired rather than genetic, degenerative or congenital causes.

Conclusion:

Despite the potential limitations of our literature review, the evidence presented here supports the observation that the vast majority of asymmetric or unilateral chorea presentations are due to acquired causes, and in this situation an exhaustive search for reversible etiology should be undertaken. However, presentation with symmetric, generalized chorea does not exclude reversible causes, and investigations should address these in addition to genetic and neurodegenerative etiologies.

Challenges in Clinicogenetic Correlations: One Phenotype - Many Genes

Background

In the field of movement disorders, what you see (phenotype) is seldom what you get (genotype). Whereas 1 phenotype was previously associated to 1 gene, the advent of next‐generation sequencing (NGS) has facilitated an exponential increase in disease‐causing genes and genotype–phenotype correlations, and the “one‐phenotype‐many‐genes” paradigm has become prominent.

Objectives

To highlight the “one‐phenotype‐many‐genes” paradigm by discussing the main challenges, perspectives on how to address them, and future directions.

Methods

We performed a scoping review of the various aspects involved in identifying the underlying molecular cause of a movement disorder phenotype.

Results

The notable challenges are (1) the lack of gold standards, overlap in clinical spectrum of different movement disorders, and variability in the interpretation of classification systems; (2) selecting which patients benefit from genetic tests and the choice of genetic testing; (3) problems in the variant interpretation guidelines; (4) the filtering of variants associated with disease; and (5) the lack of standardized, complete, and up‐to‐date gene lists. Perspectives to address these include (1) deep phenotyping and genotype–phenotype integration, (2) adherence to phenotype‐specific diagnostic algorithms, (3) implementation of current and complementary bioinformatic tools, (4) a clinical‐molecular diagnosis through close collaboration between clinicians and genetic laboratories, and (5) ongoing curation of gene lists and periodic reanalysis of genetic sequencing data.

Conclusions

Despite the rapidly emerging possibilities of NGS, there are still many steps to take to improve the genetic diagnostic yield. Future directions, including post‐NGS phenotyping and cohort analyses enriched by genotype–phenotype integration and gene networks, ought to be pursued to accelerate identification of disease‐causing genes and further improve our understanding of disease biology.

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.

Neurological Manifestations of Wilson's Disease: Pathophysiology and Localization of Each Component

Wilson's disease (WD) is an autosomal recessive disease that presents mainly with hepatic, neurological, and psychiatric manifestations. Neurological manifestations have been described in the past. Nevertheless, the pathophysiology and the clinical relevance of these manifestations have not been described in great detail in the medical literature. We aim to consolidate the knowledge about the neurological manifestations of WD and present the pathophysiology of each neurological manifestation of the disease. We will give a brief definition, the provenance, and the pathophysiology of the neurological conditions. We collected data from the National Library of Medicine (PubMed) using regular keywords and medical subject headings. Studies were selected applying the following inclusion/exclusion criteria: (1) studies that used exclusively human subjects, (2) papers published in English, and (3) papers from 1990 onward. The exclusion criteria were (1) studies that used animals, (2) papers not published in English, and (3) papers published before 1990. Additional studies were included via reference lists of identified papers and related articles featured in PubMed and Google Scholar. Copper toxicity is the principal factor for brain degeneration seen in WD. Parkinsonism seen in WD has been associated with a nigrostriatal dopaminergic deficit. Resting tremor may have the same pathophysiology as parkinsonism. Action tremor is related to an accumulation of copper in the cerebellum's vermis and hemispheres. At the same time, essential tremor can be explained due to affection of the dentate nucleus. Choreoathetosis is produced due to increased activity of the direct pathway. We did not find specifically associated pathophysiology related to dysarthria. We assume that multiple parts of the brain are involved in that problem. Putamen nucleus damage is the leading cause that explains dystonia seen in WD along with the globus palidus. We did not find a specific localization for seizures in WD, but the pathology seems to be related to decreased levels of B6 and direct toxicity of copper on the brain.

Review of Hereditary and Acquired Rare Choreas

Background:

Movement disorders are often a prominent part of the phenotype of many neurologic rare diseases. In order to promote awareness and diagnosis of these rare diseases, the International Parkinson’s and Movement Disorders Society Rare Movement Disorders Study Group provides updates on rare movement disorders.

Methods:

In this narrative review, we discuss the differential diagnosis of the rare disorders that can cause chorea.

Results:

Although the most common causes of chorea are hereditary, it is critical to identify acquired or symptomatic choreas since these are potentially treatable conditions. Disorders of metabolism and mitochondrial cytopathies can also be associated with chorea.

Discussion:

The present review discusses clues to the diagnosis of chorea of various etiologies. Authors propose algorithms to help the clinician in the diagnosis of these rare disorders.