[Phenotypic and genotypic spectrum of KMT2B dystonia. Description of three Colombian patients]. / Espectro fenotípico y genotípico de la distonía causada por el gen KMT2B. Descripción de tres casos colombianos.

INTRODUCTION: KMT2B-related dystonia is a childhood-onset movement disorder characterized by focal dystonia of the lower extremities progressing to generalized dystonia with predominant cervical, cranial, and laryngeal involvement. So far, fewer than 100 variants have been reported, the vast majority being de novo mutations. The presenting frame of KMT2B dystonia, with dysmorphology features and other complex neurologic symptoms shows the spectrum of KMT2B dystonia as a probable syndromic disease, rather than an isolated early-onset dystonia, which has been the classic view of the condition. CASE REPORTS: We report three patients who presented regression in their neurodevelopment, focal dystonia of the lower limbs with subsequent generalization, in whom two de novo variants were reported in the KMT2B gene, with a mean age of presentation lower than the average reported worldwide. CONCLUSIONS: We describe the largest local series of patients with KMT2B dystonia in Colombia (to our knowledge), which allows us to expand the genotype-phenotype relationship of this genetic dystonia. Although many affected individuals follow a similar disease course, it is important to determine clinical features that may be associated such as neurodevelopmental regression.

TITLE: Espectro fenotípico y genotípico de la distonía causada por el gen KMT2B. Descripción de tres casos colombianos.Introducción. La distonía relacionada con KMT2B es un trastorno del movimiento hipercinético, de inicio en la infancia, caracterizado inicialmente por distonía focal de las extremidades inferiores que progresa a una distonía generalizada con mayor afectación cervical, craneal y laríngea. Hasta el momento se han descrito aproximadamente 100 variantes causantes de enfermedad, y la mayoría son de novo. La presentación clínica de la distonía con hallazgos fenotípicos comunes en los pacientes, asociada a frecuente afectación del neurodesarrollo, afectación intelectual y otros trastornos del movimiento, hace pensar más en el espectro KMT2B como una condición sindrómica, más que en una distonía aislada de inicio temprano, como clásicamente se ha clasificado. Casos clínicos. Se presenta el caso de tres pacientes con regresión del neurodesarrollo, distonía focal de los miembros inferiores con posterior generalización, en quienes se identificaron tres variantes en el gen KMT2B, en dos de los casos de novo (en una de ellas se desconoce la segregación), y dos de ellas comunicadas por primera vez en la bibliografía. La edad media de presentación fue menor a la edad promedio notificada a nivel mundial. Conclusiones. Describimos una serie de pacientes colombianos con distonía DYT-KMT2B (la más grande en nuestro conocimiento a nivel local), lo que nos permite ampliar la relación genotipo-fenotipo de esta distonía genética. Si bien múltiples individuos afectados siguen un curso de enfermedad similar, es importante determinar las características clínicas que pueden estar asociadas, como la regresión del neurodesarrollo y su potencial clasificación como distonía compleja. Describimos, además, dos nuevas variantes asociadas al fenotipo.

Effects of onabotulinum toxin type A injections in patients with Meige's syndrome.

BACKGROUND: Meige's syndrome is a type of facial dystonia characterized by the simultaneous occurrence of blepharospasm and oromandibular dystonia. Although botulinum toxin type A (OBTA) injections are the standard treatment, evidence of their effectiveness and safety in this scenario is still lacking. OBJECTIVE: Our research aimed to evaluate the improvement and occurrence of side effects following injections of onabotulinum toxin type A (OBTA) in patients with Meige's syndrome. METHODS: Patients with Meige's syndrome undergoing botulinum toxin injections were enrolled in this study. We assessed dystonia intensity before and 14 days after OBTA injection using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) to measure the response of symptoms in the eyes (blepharospasm) and mouth (oromandibular dystonia). Other variables, such as dosage, side effects, and demographic data, were also recorded. RESULTS: The study included 41 participants, with a mean age of 67.7 years and a female-to-male ratio of 3.5:1. The mean BFMDRS score before the injections was 8.89, and after 14 days, it was 2.88. The most reported side effect was ptosis, with a 7.3% incidence. OBTA significantly reduced dystonia severity (p < 0.0001). The clinical response for the blepharospasm component was superior to the oromandibular dystonia component. CONCLUSION: Our results support that OBTA seems to be an effective and safe therapeutic option for treating Meige's syndrome. The effect of OBTA was more pronounced in the treatment of blepharospasm than in oromandibular dystonia.

ANTECEDENTES: A síndrome de Meige (SM) é caracterizada pela ocorrência concomitante de blefarospasmo e distonia oromandibular. Embora a toxina onabotulínica do tipo A (TBA) seja o tratamento de escolha, há uma falta de evidências sobre sua eficácia e segurança nesse cenário. OBJETIVO: O objetivo do nosso estudo foi avaliar os efeitos obtidos com a aplicação de TBA em pacientes com SM. MéTODOS: Pacientes com SM que realizam aplicação de TBA foram convidados a participar desse estudo. Os participantes foram questionados sobre a intensidade da distonia antes e 14 dias após a injeção de TBA, utilizando a Escala de Distonia de Burke-Fahn-Marsden (EDBFM) para mensurar a resposta obtida em cada segmento. Outras variáveis, como dose, ocorrência de efeitos colaterais e dados demográficos, também foram registradas. RESULTADOS: O estudo contou com 41 participantes (idade média de 67,7; razão de 3,5 pacientes do sexo feminino para cada participante do sexo masculino). O escore médio na EDBFM antes das aplicações de TBA era 8,89, e, após 14 dias, 2,88. O efeito colateral mais reportado foi ptose (7.3%). A TBA foi capaz de reduzir a severidade da distonia (p < 0.0001), principalmente do blefarospasmo. CONCLUSãO: Nossos resultados corroboram que a TBA é uma terapêutica eficaz e segura no tratamento da SM. O efeito da TBA é superior no manejo do blefarospasmo em relação à distonia oromandibular.

Genetic Update and Treatment for Dystonia.

A neurological condition called dystonia results in abnormal, uncontrollable postures or movements because of sporadic or continuous muscular spasms. Several varieties of dystonia can impact people of all ages, leading to severe impairment and a decreased standard of living. The discovery of genes causing variations of single or mixed dystonia has improved our understanding of the disease's etiology. Genetic dystonias are linked to several genes, including pathogenic variations of VPS16, TOR1A, THAP1, GNAL, and ANO3. Diagnosis of dystonia is primarily based on clinical symptoms, which can be challenging due to overlapping symptoms with other neurological conditions, such as Parkinson's disease. This review aims to summarize recent advances in the genetic origins and management of focal dystonia.

Myoclonus and Dystonia as Recurrent Presenting Features in Patients with the SCA21-Associated TMEM240 p.Pro170Leu Variant.

Background: Spinocerebellar ataxia 21 (SCA21) is a rare neurological disorder caused by heterozygous variants in TMEM240. A growing, yet still limited number of reports suggested that hyperkinetic movements should be considered a defining component of the disease. Case Series: We describe two newly identified families harboring the recurrent pathogenic TMEM240 p.Pro170Leu variant. Both index patients and the mother of the first proband developed movement disorders, manifesting as myoclonic dystonia and action-induced dystonia without co-occurring ataxia in one case, and pancerebellar syndrome complicated by action-induced dystonia in the other. We reviewed the literature on TMEM240 variants linked to hyperkinetic disorders, comparing our cases to described phenotypes. Discussion: Adding to prior preliminary observations, our series highlights the relevance of hyperkinetic movements as clinically meaningful features of SCA21. TMEM240 mutation should be included in the differential diagnosis of myoclonic dystonia and ataxia-dystonia syndromes.

The integrated stress response pathway and neuromodulator signaling in the brain: lessons learned from dystonia.

The integrated stress response (ISR) is a highly conserved biochemical pathway involved in maintaining proteostasis and cell health in the face of diverse stressors. In this Review, we discuss a relatively noncanonical role for the ISR in neuromodulatory neurons and its implications for synaptic plasticity, learning, and memory. Beyond its roles in stress response, the ISR has been extensively studied in the brain, where it potently influences learning and memory, and in the process of synaptic plasticity, which is a substrate for adaptive behavior. Recent findings demonstrate that some neuromodulatory neuron types engage the ISR in an "always-on" mode, rather than the more canonical "on-demand" response to transient perturbations. Atypical demand for the ISR in neuromodulatory neurons introduces an additional mechanism to consider when investigating ISR effects on synaptic plasticity, learning, and memory. This basic science discovery emerged from a consideration of how the ISR might be contributing to human disease. To highlight how, in scientific discovery, the route from starting point to outcomes can often be circuitous and full of surprise, we begin by describing our group's initial introduction to the ISR, which arose from a desire to understand causes for a rare movement disorder, dystonia. Ultimately, the unexpected connection led to a deeper understanding of its fundamental role in the biology of neuromodulatory neurons, learning, and memory.

Posterior Interosseous Neuropathy with Peripheral Dystonia: A Case Report.

Background: Posterior interosseous neuropathy is an uncommon cause of peripheral dystonia. Case Report: A 62-year-old man awakened and noticed right finger drop. A neurological examination revealed posterior interosseous neuropathy with dystonia-like finger movements. Abnormal movements were predominantly observed in the right thumb, ring finger, and little finger. Within 2 weeks, the muscle weakness in the right fingers had completely improved. However, a brief abnormal posture of the right thumb was persistent. Discussion: The residual abnormal posture of the right thumb may reflect pre-existing motor control abnormalities, which may have contributed to the onset of posterior interosseous neuropathy-associated peripheral dystonia.

Successful treatment of cranial dystonia using a Zolpidem+Melatonin combination: A video case-series.

INTRODUCTION: Cranial dystonias (CrD) are challenging to treat. Oral pharmacotherapy is often sub-optimal, while delicate anatomy and limited availability of skilled botulinum toxin injectors makes this approach risky, and often difficult to access; neurosurgical options e.g. deep brain stimulation, are high-risk in the elderly populations most affected. We observed significant improvement in CrD in 2 patients prescribed Zolpidem+Melatonin combination treatment for insomnia, and therefore trialled this treatment in a further 4 patients with CrD. METHODS: Six patients were treated with Zolpidem+Melatonin. Pre- and post-treatment videotaped clinical examinations were blindly rated by an independent assessor (EM) and scored using the 'Facial and Oral Movements' section of the abnormal involuntary movements scale (AIMS), as well as the Jankovic rating scale for blepharospasm. RESULTS: Dystonic features, as measured by the abnormal involuntary movements scale (AIMS) improved by an average of 75% after treatment (6.5±3.1 before treatment to 1.7 +/- 0.8 after treatment). Improvements were also observed in blepharospasm severity scores, and in cervical dystonic features. CONCLUSION: Zolpidem+Melatonin combination treatment represents a safe and effective treatment for CrD. Low cost and wide availability makes it an attractive option, particularly in resource-constrained healthcare settings, or in patients who have failed, or lack access to alternatives.

CHD8-related disorders redefined: an expanding spectrum of dystonic phenotypes.

BACKGROUND: Heterozygous loss-of-function variants in CHD8 have been associated with a syndromic neurodevelopmental-disease spectrum, collectively referred to as CHD8-related neurodevelopmental disorders. Several different clinical manifestations, affecting neurodevelopmental and systemic domains, have been described, presenting with highly variable expressivity. Some expressions are well established and comprise autism spectrum disorders, psychomotor delay with cognitive impairment, postnatal overgrowth with macrocephaly, structural brain abnormalities, gastrointestinal disturbances, and behavioral and sleep-pattern problems. However, the complete phenotypic spectrum of CHD8-related disorders is still undefined. In 2021, our group described two singular female patients with CHD8-related neurodevelopmental disorder and striking dystonic manifestations, prompting the suggestion that dystonia should be considered a possible component of this condition. CASE SERIES PRESENTATION: We describe three additional unrelated female individuals, each carrying a different CHD8 frameshift variant and whose clinical presentations were primarily characterized by young-onset dystonia. Their dystonic manifestations were remarkably heterogeneous and ranged from focal, exercise-dependent, apparently isolated forms to generalized permanent phenotypes accompanied by spasticity and tremor. Neurocognitive impairment and autistic behaviors, typical of CHD8-related disorders, were virtually absent or at the mild end of the spectrum. CONCLUSIONS: This work validates our previous observation that dystonia is part of the phenotypic spectrum of CHD8-related neurodevelopmental disorders with potential female preponderance, raising new challenges and opportunities in the diagnosis and management of this condition. It also highlights the importance of in-depth neurologic phenotyping of patients carrying variants associated with neurodevelopmental disorders, as the connection between neurodevelopmental and movement disorders is proving closer than previously appreciated.

Musician's dystonia in a percussionist - clinical video analysis and botulinum toxin intervention: a case report.

OBJECTIVE: Musician's focal hand dystonia is a painless task-specific focal dystonia, which presents with involuntary movements, abnormal postures, and loss of fine motor dexterity. We report here the case of a 63-year-old male, percussionist, with african ethnicity, with musician's focal hand dystonia who was treated with botulinum toxin, and describe the results at 4-weeks follow up. METHODS: Clinical examination and video analysis revealed abnormal flexion of the 3rd finger, followed by flexion of the 4th and 5th fingers while playing the congas. Based on these findings, a diagnosis of musician's focal hand dystonia was established. Ten units of botulinum toxin were injected into the muscle fibres of the flexor digitorum superficialis corresponding to the 4th finger using electromyography and ultrasound guidance. Four weeks later, the patient reported a subjective 60% improvement in his performance. He emphasized the effect of botulinum toxin on performance speed and tension over the forearm and hand. CONCLUSION: Botulinum toxin is not a definitive treatment for musician's focal hand dystonia, but it may potentiate other definitive rehabilitation techniques. More research is needed to determine the long-term effects of botulinum toxin on function enhancement in musician's focal hand dystonia.

Emergence of lingual dystonia and strabismus in early-onset SCN8A self-limiting familial infantile epilepsy.

Pathogenic variants in SCN8A are associated with a broad phenotypic spectrum, including Self-Limiting Familial Infantile Epilepsy (SeLFIE), characterized by infancy-onset age-related seizures with normal development and cognition. Movement disorders, particularly paroxysmal kinesigenic dyskinesia typically arising after puberty, may represent another core symptom. We present the case of a 1-year-old girl with a familial disposition to self-limiting focal seizures from the maternal side and early-onset orofacial movement disorders associated with SCN8A-SeLFIE. Brain MRI was normal. Genetic testing revealed a maternally inherited SCN8A variant [c.4447G > A; p.(Glu1483Lys)]. After the introduction of valproic acid, she promptly achieved seizure control as well as complete remission of strabismus and a significant decrease in episodes of tongue deviation. Family history, genetic findings, and epilepsy phenotype are consistent with SCN8A-SeLFIE. Movement disorders are an important part of the SCN8A phenotypic spectrum, and this case highlights the novel early-onset orofacial movement disorders associated with this condition. The episodes of tongue deviation and protrusion suggest focal oromandibular (lingual) dystonia. Additionally, while infantile strabismus or esophoria is a common finding in healthy individuals, our case raises the possibility of an ictal origin of the strabismus. This study underscores the importance of recognizing and addressing movement disorders in SCN8A-SeLFIE patients, particularly the rare early-onset orofacial manifestations. It adds to the growing body of knowledge regarding the diverse clinical presentations of SCN8A-associated disorders and suggests potential avenues for clinical management and further research.

Dissecting genetic architecture of rare dystonia: genetic, molecular and clinical insights.

BACKGROUND: Dystonia is one of the most common movement disorders. To date, the genetic causes of dystonia in populations of European descent have been extensively studied. However, other populations, particularly those from the Middle East, have not been adequately studied. The purpose of this study is to discover the genetic basis of dystonia in a clinically and genetically well-characterised dystonia cohort from Turkey, which harbours poorly studied populations. METHODS: Exome sequencing analysis was performed in 42 Turkish dystonia families. Using co-expression network (CEN) analysis, identified candidate genes were interrogated for the networks including known dystonia-associated genes and genes further associated with the protein-protein interaction, animal model-based characteristics and clinical findings. RESULTS: We identified potentially disease-causing variants in the established dystonia genes (PRKRA, SGCE, KMT2B, SLC2A1, GCH1, THAP1, HPCA, TSPOAP1, AOPEP; n=11 families (26%)), in the uncommon forms of dystonia-associated genes (PCCB, CACNA1A, ALDH5A1, PRKN; n=4 families (10%)) and in the candidate genes prioritised based on the pathogenicity of the variants and CEN-based analyses (n=11 families (21%)). The diagnostic yield was found to be 36%. Several pathways and gene ontologies implicated in immune system, transcription, metabolic pathways, endosomal-lysosomal and neurodevelopmental mechanisms were over-represented in our CEN analysis. CONCLUSIONS: Here, using a structured approach, we have characterised a clinically and genetically well-defined dystonia cohort from Turkey, where dystonia has not been widely studied, and provided an uncovered genetic basis, which will facilitate diagnostic dystonia research.

RANBP17 Overexpression Restores Nucleocytoplasmic Transport and Ameliorates Neurodevelopment in Induced DYT1 Dystonia Motor Neurons.

DYT1 dystonia is a debilitating neurological movement disorder, and it represents the most frequent and severe form of hereditary primary dystonia. There is currently no cure for this disease due to its unclear pathogenesis. In our previous study utilizing patient-specific motor neurons (MNs), we identified distinct cellular deficits associated with the disease, including a deformed nucleus, disrupted neurodevelopment, and compromised nucleocytoplasmic transport (NCT) functions. However, the precise molecular mechanisms underlying these cellular impairments have remained elusive. In this study, we revealed the genome-wide changes in gene expression in DYT1 MNs through transcriptomic analysis. We found that those dysregulated genes are intricately involved in neurodevelopment and various biological processes. Interestingly, we identified that the expression level of RANBP17, a RAN-binding protein crucial for NCT regulation, exhibited a significant reduction in DYT1 MNs. By manipulating RANBP17 expression, we further demonstrated that RANBP17 plays an important role in facilitating the nuclear transport of both protein and transcript cargos in induced human neurons. Excitingly, the overexpression of RANBP17 emerged as a substantial mitigating factor, effectively restoring impaired NCT activity and rescuing neurodevelopmental deficits observed in DYT1 MNs. These findings shed light on the intricate molecular underpinnings of impaired NCT in DYT1 neurons and provide novel insights into the pathophysiology of DYT1 dystonia, potentially leading to the development of innovative treatment strategies.

The role of genetics in the treatment of dystonia with deep brain stimulation: Systematic review and Meta-analysis.

BACKGROUND: Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions that lead to involuntary postures or repetitive movements. Genetic mutations are being increasingly recognized as a cause of dystonia. Deep brain stimulation (DBS) is one of the limited treatment options available. However, there are varying reports on its efficacy in genetic dystonias. This systematic review of the characteristics of genetic dystonias treated with DBS and their outcomes aims to aid in the evaluation of eligibility for such treatment. METHODS: We performed a PUBMED search of all papers related to genetic dystonias and DBS up until April 2022. In addition to performing a systematic review, we also performed a meta-analysis to assess the role of the mutation on DBS response. We included cases that had a confirmed genetic mutation and DBS along with pre-and post-operative BFMDRS. RESULTS: Ninety-one reports met our inclusion criteria and from them, 235 cases were analyzed. Based on our analysis DYT-TOR1A dystonia had the best evidence for DBS response and Rapid-Onset Dystonia Parkinsonism was among the least responsive to DBS. CONCLUSION: While our report supports the role of genetics in DBS selection and response, it is limited by the rarity of the individual genetic conditions, the reliance on case reports and case series, and the limited ability to obtain genetic testing on a large scale in real-time as opposed to retrospectively as in many cases.

An Evidence-Based Update on Anticholinergic Use for Drug-Induced Movement Disorders.

Drug-induced movement disorders (DIMDs) are associated with use of dopamine receptor blocking agents (DRBAs), including antipsychotics. The most common forms are drug-induced parkinsonism (DIP), dystonia, akathisia, and tardive dyskinesia (TD). Although rare, neuroleptic malignant syndrome (NMS) is a potentially life-threatening consequence of DRBA exposure. Recommendations for anticholinergic use in patients with DIMDs were developed on the basis of a roundtable discussion with healthcare professionals with extensive expertise in DIMD management, along with a comprehensive literature review. The roundtable agreed that "extrapyramidal symptoms" is a non-specific term that encompasses a range of abnormal movements. As such, it contributes to a misconception that all DIMDs can be treated in the same way, potentially leading to the misuse and overprescribing of anticholinergics. DIMDs are neurobiologically and clinically distinct, with different treatment paradigms and varying levels of evidence for anticholinergic use. Whereas evidence indicates anticholinergics can be effective for DIP and dystonia, they are not recommended for TD, akathisia, or NMS; nor are they supported for preventing DIMDs except in individuals at high risk for acute dystonia. Anticholinergics may induce serious peripheral adverse effects (e.g., urinary retention) and central effects (e.g., impaired cognition), all of which can be highly concerning especially in older adults. Appropriate use of anticholinergics therefore requires careful consideration of the evidence for efficacy (e.g., supportive for DIP but not TD) and the risks for serious adverse events. If used, anticholinergic medications should be prescribed at the lowest effective dose and for limited periods of time. When discontinued, they should be tapered gradually.