Structural Brain Correlates of Sleep Microstructure in Spinocerebellar Ataxia Type 2 and its Role on Clinical Phenotype.

The influence of brain atrophy on sleep microstructure in Spinocerebellar Ataxias (SCAs) has not been extensively explored limiting the use of these sleep traits as surrogate biomarkers of neurodegeneration and clinical phenotype. The objective of the study is to explore the relationship between sleep microstructure and brain atrophy in SCA2 and its role in the clinical phenotype. Fourteen SCA2 mutation carriers (7 pre-manifest and 7 manifest subjects) underwent polysomnographic, structural MRI, and clinical assessments. Particularly, markers of REM and non-REM sleep microstructure, measures of cerebellar and brainstem atrophy, and clinical scores were analyzed through correlation and mediation analyses. The sleep spindle activity exhibited a negative correlation with the number of trials required to complete the verbal memory test (VMT), and a positive correlation with the cerebellar volume, but the significance of the latter correlation did not survive multiple testing corrections. However, the causal mediation analyses unveiled that sleep spindle activity significantly mediates the association between cerebellar atrophy and VMT performance. Regarding REM sleep, both phasic EMG activity and REM sleep without atonia exhibited significant associations with pontine atrophy and disease severity measures. However, they did not demonstrate a causal mediation effect between the atrophy measures and disease severity. Our study provides evidence about the association of the pontocerebellar atrophy with sleep microstructure in SCA2 offering insights into the cerebellar involvement in cognition via the control of the sleep spindle activity. Therefore, our findings may help to understand the disease pathogenesis and to better characterize sleep microstructure parameters as disease biomarkers.Clinical trial registration number (TRN): No applicable.

Serum S100ß Levels Are Linked with Cognitive Decline and Peripheral Inflammation in Spinocerebellar Ataxia Type 2.

Experimental and clinical studies have indicated a potential role of the protein S100ß in the pathogenesis and phenotype of neurodegenerative diseases. However, its impact on spinocerebellar ataxia type 2 (SCA2) remains to be elucidated. The objective of the study is to determine the serum levels of S100ß in SCA2 and its relationship with molecular, clinical, cognitive, and peripheral inflammatory markers of the disease. Serum concentrations of S100ß were measured by enzyme-linked immunosorbent assay in 39 SCA2 subjects and 36 age- and gender-matched controls. Clinical scores of ataxia, non-ataxia symptoms, cognitive dysfunction, and some blood cell count-derived inflammatory indices were assessed. The SCA2 individuals manifested S100ß levels similar to the control group, at low nanomolar concentrations. However, the S100ß levels were directly associated with a better performance of cognitive evaluation within the SCA2 cohort. Moreover, the S100ß levels were inversely correlated with most peripheral inflammatory indices. Indeed, the neutrophil-to-lymphocyte ratio significantly mediated the effect of serum S100ß on cognitive performance, even after controlling for the ataxia severity in the causal mediation analysis. Our findings suggested that, within physiologic concentrations, the protein S100ß exerts a neuroprotective role against cognitive dysfunction in SCA2, likely via the suppression of pro-inflammatory mechanisms.

Optic Disc and Retinal Architecture Changes in Patients with Spinocerebellar Ataxia Type 2.

BACKGROUND: ATXN2 is the causative gene of spinocerebellar ataxia type 2 (SCA2) and has been implicated in glaucoma pathogenesis. Therefore, studying ocular changes in SCA2 could uncover clinically relevant changes. OBJECTIVE: The aim was to investigate optic disc and retinal architecture in SCA2. METHODS: We evaluated 14 patients with SCA2 and 26 controls who underwent intraocular pressure measurement, fundoscopy, and macular and peripapillary spectral domain optical coherence tomography (SD-OCT). We compared SD-OCT measurements in SCA2 and controls, and the frequency of glaucomatous changes among SCA2, controls, and 76 patients with other SCAs (types 1, 3, 6, and 7). RESULTS: The macula, peripapillary retinal nerve fiber and inner plexiform layers were thinner in SCA2 than in controls. Increased cup-to-disc ratio was more frequent in SCA2 than in controls and other SCAs. CONCLUSIONS: Ocular changes are part of SCA2 phenotype. Future studies should further investigate retinal and optic nerve architecture in this disorder.

A model for the dynamics of expanded CAG repeat alleles: ATXN2 and ATXN3 as prototypes.

Background: Spinocerebellar ataxia types 2 (SCA2) and 3 (SCA3/MJD) are diseases due to dominant unstable expansions of CAG repeats (CAGexp). Age of onset of symptoms (AO) correlates with the CAGexp length. Repeat instability leads to increases in the expanded repeats, to important AO anticipations and to the eventual extinction of lineages. Because of that, compensatory forces are expected to act on the maintenance of expanded alleles, but they are poorly understood. Objectives: we described the CAGexp dynamics, adapting a classical equation and aiming to estimate for how many generations will the descendants of a de novo expansion last. Methods: A mathematical model was adapted to encompass anticipation, fitness, and allelic segregation; and empirical data fed the model. The arbitrated ancestral mutations included in the model had the lowest CAGexp and the highest AO described in the literature. One thousand generations were simulated until the alleles were eliminated, fixed, or 650 generations had passed. Results: All SCA2 lineages were eliminated in a median of 10 generations. In SCA3/MJD lineages, 593 were eliminated in a median of 29 generations. The other ones were eliminated due to anticipation after the 650th generation or remained indefinitely with CAG repeats transitioning between expanded and unexpanded ranges. Discussion: the model predicted outcomes compatible with empirical data - the very old ancestral SCA3/MJD haplotype, and the de novo SCA2 expansions -, which previously seemed to be contradictory. This model accommodates these data into understandable dynamics and might be useful for other CAGexp disorders.

COVID-19 Impacts the Mental Health and Speech Function in Spinocerebellar Ataxia Type 2: Evidences from a Follow-Up Study.

Limited evidence suggests that the SARS-CoV-2 infection can accelerate the progression of neurodegenerative diseases, but this has been not verified in the spinocerebellar ataxias (SCA). The objective of this study is to assess the impact of COVID-19 on the mental health and motor features of SCA2. A follow-up study was carried out in 170 Cuban SCA2 subjects and 87 community controls between 2020 and 2021. All subjects underwent a structured questionnaire to assess the risks of exposure to COVID-19, the confirmation of COVID-19 diagnosis, and the Hospital Anxiety and Depression Scale (HADS). Moreover, 36 subjects underwent the Scale for the Assessment and Rating of ataxia (SARA). The risk of exposure to SARS-CoV-2 and the frequency of COVID-19 were similar between the ataxia cohort and the community controls. Within the ataxia group, significantly increased HADS scores existed at the 2nd visit in both groups, but this increase was more evident for the infected group regarding the depression score. Moreover, a significant within-group increase of SARA score was observed in the infected group but not the non-infected group, which was mainly mediated by the significant increase of the speech item score in the infected group. Similar results were observed within the subgroup of preclinical carriers. Our study identified no selective vulnerability nor protection to COVID-19 in SCA2, but once infected, the patients experienced a deterioration of mental health and speech function, even at preclinical disease stage. These findings set rationales for tele-health approaches that minimize the detrimental effect of COVID-19 on SCA2 progression and identify SCA2 individuals as clinical model to elucidate the link between SARS-CoV-2 infection and neurodegeneration.

Signo de la cruz en una paciente peruana con ataxia espinocerebelosa tipo 2: reporte de un caso / Hot cross bun sign in a Peruvian patient with spinocerebellar ataxia type 2: A case report

RESUMEN La ataxia espinocerebelosa tipo 2 (SCA2) es una enfermedad neurodegenerativa hereditaria autosómica dominante, causada por una expansión anormal del trinucleótido CAG en el gen ATXN2. La SCA2 se presenta habitualmente en la edad adulta, con ataxia progresiva asociada a neuropatía periférica, alteración de movimientos oculares, parkinsonismo, entre otros síntomas. Exámenes auxiliares aplicables incluyen pruebas bioquímicas, neuroimágenes, como resonancia magnética cerebral, y estudio genético molecular. Describimos, por primera vez en la población peruana, el caso de una mujer de mediana edad con diagnóstico confirmado de SCA2, cuya resonancia magnética cerebral muestra el signo de la cruz (o hot cross bun sign).

ABSTRACT Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant inherited neurodegenerative disease, caused by an abnormal CAG trinucleotide expansion in the ATXN2 gene. SCA2 usually occurs in adulthood, with progressive ataxia associated with peripheral neuropathy, impaired eye movements, parkinsonism, and other symptoms. Auxiliary exams include biochemical tests, neuroimaging such as brain MRI, and a molecular genetic study. We describe, for the first time in the Peruvian population, the case of a middle-aged woman with a confirmed diagnosis of SCA2, whose brain MRI shows the "Hot Cross Bun Sign".

Peripheral Inflammation Links with the Severity of Clinical Phenotype in Spinocerebellar Ataxia 2.

BACKGROUND: The role of peripheral inflammation in spinocerebellar ataxia type 2 (SCA2) is unknown. OBJECTIVE: The objective of this study was to identify peripheral inflammation biomarkers and their relationship with the clinical and molecular features. METHODS: Blood cell count-derived inflammatory indices were measured in 39 SCA2 subjects and their matched controls. Clinical scores of ataxia, nonataxia, and cognitive dysfunction were assessed. RESULTS: The neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the Systemic Inflammation Index (SII), and the Aggregate Index of Systemic Inflammation (AISI) were significantly increased in SCA2 subjects compared with controls. The increases in PLR, SII, and AISI were even observed in preclinical carriers. NLR, PLR, and SII were correlated with the Scale for the Assessment and Rating of Ataxia speech item score rather than with the total score. The NLR and SII were correlated with the nonataxia and the cognitive scores. CONCLUSIONS: Peripheral inflammatory indices are biomarkers in SCA2, which may help to design future immunomodulatory trials and advance our understanding of the disease. © 2023 International Parkinson and Movement Disorder Society.

Curso optativo sobre ataxia espinocerebelosa tipo 2 en la Universidad de Ciencias Médicas de Holguín

Introducción: Recientemente inició la formación de profesionales en una nueva modalidad de Programas Técnico Superior de Ciclo Corto en la especialidad Neurofisiología Clínica, en la Universidad de Ciencias Médicas de Holguín, atendiendo a la alta incidencia de enfermedades neurológicas, como la ataxia espinocerebelosa tipo 2, que constituye un serio problema de salud en Cuba. Un programa de curso optativo que aborde esta temática, contribuye al conocimiento de esta enfermedad para su investigación y posibles tratamientos. Objetivo: Diseñar un programa de curso optativo sobre diagnóstico e intervención físico-terapéutica en la fase prodrómica de la ataxia espinocerebelosa tipo 2 para estudiantes de Neurofisiología Clínica Primer Año en la Facultad de Enfermería ¨Arides Estévez Sánchez¨ de Holguín. Método: Se realizó una investigación didáctica metodológica utilizando los métodos empíricos: observación; teóricos: histórico-lógico, estudio documental, dialéctico; análisis-síntesis e inducción-deducción. Resultados: Se propuso un programa para curso optativo basado en la búsqueda de información científica y métodos empíricos, el cual fue estructurado en cuatro temas, con carácter presencial y duración de 24 horas. Se presentaron los contenidos por temas, objetivos, conocimientos esenciales a adquirir, habilidades principales a dominar y sistema de evaluación. Conclusiones: La aplicación de este programa contribuye a desarrollar habilidades en los profesionales en formación, en el conocimiento de la fase prodrómica de esta enfermedad.

Introduction: It recently began the training of professionals in a new modality of Programas Técnico Superior de Ciclo Corto (Short Cycle Superior Technical Programs) in the Clinical Neurophysiology specialty, at the Universidad de Ciencias Médicas de Holguín, attending to the high incidence of neurological diseases, such as spinocerebellar ataxia type 2, which constitutes a serious health problem in Cuba. This is an elective course program that addresses this topic and contributes to the knowledge of this disease, in order to improve research and possible treatments. Objective: To design an elective course program on diagnosis and physical-therapeutic intervention in the prodromal phase of spinocerebellar ataxia type 2 for first year Clinical Neurophysiology students at the ¨Arides Estévez Sánchez¨ School of Nursing in Holguín. Method: A methodological didactic research was carried out using the empirical methods: observation; theoretical: historical-logical, documentary study, dialectical; analysis-synthesis and induction-deduction. Results: A program was proposed for an optional course, based on the search for scientific information and empirical methods, which was structured in four themes, in face-to-face modality and with a duration of 24 hours. The contents were presented by themes, objectives, essential knowledge to acquire, main skills to master and evaluation system. Conclusions: The application of this program contributes to developing skills in training professionals, in the knowledge of the prodromal phase of this disease.

Introdução: Iniciou-se recentemente a formação de profissionais em uma nova modalidade de Programas Técnicos Superiores de Ciclo Curto na especialidade de Neurofisiologia Clínica, na Universidad de Ciencias Médicas de Holguín, atendendo à alta incidência de doenças neurológicas, como a ataxia espinocerebelar tipo 2, que constitui um grave problema de saúde em Cuba. Um programa de disciplina eletiva que aborde esse tema contribui para o conhecimento dessa doença para sua investigação e possíveis tratamentos. Objetivo: Elaborar um programa de disciplina eletiva sobre diagnóstico e intervenção fisioterapêutica na fase prodrômica da ataxia espinocerebelar tipo 2 para alunos do primeiro ano de Neurofisiologia Clínica da Escola de Enfermagem ¨Arides Estévez Sánchez¨ de Holguín. Método: Foi realizada uma pesquisa didática metodológica utilizando os métodos empíricos: observação; teórico: histórico-lógico, estudo documental, dialético; análise-síntese e indução-dedução. Resultados: Foi proposto um programa para um curso opcional baseado na busca de informações científicas e métodos empíricos, o qual foi estruturado em quatro temas, com caráter presencial e duração de 24 horas. Os conteúdos foram apresentados por temas, objetivos, conhecimentos essenciais a adquirir, principais competências a dominar e sistema de avaliação. Conclusões: A aplicação deste programa contribui para o desenvolvimento de competências nos profissionais em formação, no conhecimento da fase prodrómica desta doença.

Erythropoietin in Spinocerebellar Ataxia Type 2: Feasibility and Proof-of-Principle Issues from a Randomized Controlled Study.

BACKGROUND: Several pieces of evidence have shown the neurotrophic effect of erythropoietin (EPO) and its introduction in the therapeutic practice of neurological diseases. However, its usefulness in the treatment of spinocerebellar ataxia type 2 (SCA2) has not been proven despite the fact that it is endogenously reduced in these patients. OBJECTIVE: The study aims to investigate the safety, tolerability, and clinical effects of a nasally administered recombinant EPO in SCA2 patients. METHODS: Thirty-four patients were enrolled in this double-blind, randomized, placebo-controlled, phase I-II clinical trial of the nasally administered human-recombinant EPO (NeuroEPO) for 6 months. The primary outcome was the change in the spinocerebellar ataxia functional index (SCAFI), while other motor, neuropsychological, and oculomotor measures were assessed. RESULTS: The 6-month changes in SCAFI score were slightly higher in the patients allocated to NeuroEPO treatment than placebo in spite of the important placebo effect observed for this parameter. However, saccade latency was significantly decreased in the NeuroEPO group but not in placebo. The frequency and severity of adverse events were similar between both groups, without evidences of hematopoietic activity of the drug. CONCLUSIONS: This study demonstrated the safety and tolerability of NeuroEPO in SCA2 patients after 6 months of treatments and suggested a small clinical effect of this drug on motor and cognitive abnormalities, but confirmatory studies are warranted. © 2022 International Parkinson and Movement Disorder Society.

Weight loss is correlated with disease severity in Spinocerebellar ataxia type 2: a cross-sectional cohort study.

BACKGROUND: Body weight changes occur frequently during advanced stages of Spinocerebellar Ataxia type 2 (SCA2), nevertheless limited information exists on biomarkers of nutritional status of these patients. OBJECTIVE.: To assess changes in surrogate nutritional markers of SCA2 patients; to explore their associations with expanded CAG repeats and disease severity. METHODS: One-hundred-thirteen SCA2 patients and 50 healthy controls underwent a comprehensive anthropometrical and biochemical assessment protocol of the nutritional status. Neurological and genotype assessments were also performed. RESULTS: A decrease in weight, body mass index (BMI), cutaneous skinfold thickness, fat mass, arm muscle circumference, calf circumference and skeletal muscle mass was observed in SCA2 patients compared to the controls. The total/HDL cholesterol ratio was significantly reduced in patients. BMI was correlated with the age at onset. Overall, anthropometric measures were correlated with clinical markers of disease severity and were more evident in severe and moderate cases. CONCLUSIONS: Using anthropometric measures in the assessment of the nutritional status of SCA2 patients might provide hints about pathophysiological mechanisms that underlie metabolic abnormalities in SCA2. Anthropometric are close related with disease severity and progression, and trigger preventive therapies aimed to ameliorate weight loss and wasting in these patients.

Cognitive Decline Is Closely Associated with Ataxia Severity in Spinocerebellar Ataxia Type 2: a Validation Study of the Schmahmann Syndrome Scale.

The cerebellar cognitive affective syndrome scale (CCAS-S) was designed to detect specific cognitive dysfunctions in cerebellar patients but is scarcely validated in spinocerebellar ataxias (SCA). The objective of this study is to determine the usefulness of the CCAS-S in a Cuban cohort of SCA2 patients and the relationship of its scores with disease severity. The original scale underwent a forward and backward translation into Spanish language, followed by a pilot study to evaluate its comprehensibility. Reliability, discriminant, and convergent validity assessments were conducted in 64 SCA2 patients and 64 healthy controls matched for sex, age, and education. Fifty patients completed the Montreal Cognitive Assessment (MoCA) test. The CCAS-S showed an acceptable internal consistency (Cronbach's alpha = 0.74) while its total raw score and the number of failed tests showed excellent (ICC = 0.94) and good (ICC = 0.89) test-retest reliability, respectively. Based on original cut-offs, the sensitivity of CCAS-S to detect possible/probable/definite CCAS was notably high (100%/100%/91%), but specificities were low (6%/30/64%) because the decreased specificity observed in four items. CCAS-S performance was significantly influenced by ataxia severity in patients and by education in both groups. CCAS-S scores correlated with MoCA scores, but showed higher sensitivity than MoCA to detect cognitive impairments in patients. The CCAS-S is particularly useful to detect cognitive impairments in SCA2 but some transcultural and/or age and education-dependent adaptations could be necessary to improve its diagnostic properties. Furthermore, this scale confirmed the parallelism between cognitive and motor deficits in SCA2, giving better insights into the disease pathophysiology and identifying novel outcomes for clinical trials.

Aproximación a la ingesta nutricional en pacientes con Ataxia Espinocerebelosa tipo 2 / An approach to nutritional intake in patients with Spinocerebellar Ataxia type 2

Introducción: La Ataxia Espinocerebelosa tipo 2 (SCA2) es una enfermedad neurodegenerativa y hereditaria. No se ha realizado ningún estudio para la caracterización de la ingesta nutricional en pacientes cubanos con SCA2. Objetivo: Comprobar la reproducibilidad y fiabilidad del método de recordatorio de 24 horas para la evaluación de la ingesta nutricional en pacientes cubanos con SCA2, y obtener una caracterización preliminar de la misma en estos pacientes. Material y Métodos: Se realizó un estudio transversal con test-retest que incluyó 35 pacientes con diagnóstico de SCA2. Se empleó el cuestionario dietético de recordatorio de 24 horas incorporado al sistema CERES+. Resultados: Se obtuvieron correlaciones altamente significativas entre la primera y segunda mediciones para la ingesta estimada de energía, nutrientes y según grupos de alimentos. En la mayoría de los elementos relativos a la ingesta estimada de energía y nutrientes, y en todos los grupos de alimentos, se obtuvieron coeficientes de correlación intraclase (0,75. Se obtuvieron diferencias significativas entre pacientes de sexo masculino o femenino en cuanto a la ingesta de proteínas, carbohidratos, cobalamina, hierro, sodio y cinc. Se obtuvo un incremento en la ingesta de sodio y una disminución en la ingesta de ácido fólico y cobre, con respecto a las recomendaciones de ingesta nutricional diaria para la población cubana. Conclusiones: Se comprobó la elevada reproducibilidad y fiabilidad del cuestionario dietético recordatorio de 24 horas para la evaluación de la ingesta nutricional en pacientes con SCA2 y se logró una caracterización preliminar de la ingesta nutricional en estos pacientes(AU)

Introduction: Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative and inherited disorder. No study has been conducted to characterize nutritional intake in Cuban SCA2 patients. Objective: To test the reproducibility and reliability of the 24-hour dietary recall method for the assessment of nutritional intake in Cuban patients with SCA2, as well as to obtain a preliminary characterization of nutritional intake in these patients. Material and Methods: A cross-sectional test-retest study was conducted on 35 SCA2 patients. The 24-hour dietary recall questionnaire in the CERES+ system was used. Results: Highly significant correlations between the first and second measurements were obtained for energy and nutrients intake, and according to food groups. Intraclass correlation coefficients higher than 0.75 were obtained for energy and most of the nutrients and according to food groups. Significant differences were obtained between male and female patients in terms of proteins, carbohydrates, cobalamin, iron, sodium, and zinc intake. An increase in sodium intake and a decrease in folic acid and copper intake were obtained. SCA2 patients showed increased sodium intake, and decreased folic acid and copper intake relative to nutritional intake recommendations for the Cuban population. Conclusions: The 24-hour recall dietary questionnaire is reproducible and reliable for the assessment of nutritional intake in SCA2 patients. Preliminary characterization of nutritional intake in SCA2 patients was obtained(AU)

Spinocerebellar ataxia type 2 from an evolutionary perspective: Systematic review and meta-analysis.

Dominant diseases due to expanded CAG repeat tracts, such as spinocerebellar ataxia type 2 (SCA2), are prone to anticipation and worsening of clinical picture in subsequent generations. There is insufficient data about selective forces acting on the maintenance of these diseases in populations. We made a systematic review and meta-analysis on the effect of the CAG length over age at onset, instability of transmissions, anticipation, de novo or sporadic cases, fitness, segregation of alleles, and ancestral haplotypes. The correlation between CAG expanded and age at onset was r2  = 0.577, and transmission of the mutant allele was associated with an increase of 2.42 CAG repeats in the next generation and an anticipation of 14.62 years per generation, on average. One de novo and 18 sporadic cases were detected. Affected SCA2 individuals seem to have more children than controls. The expanded allele was less segregated than the 22-repeat allele in children of SCA2 subjects. Several ancestral SCA2 haplotypes were published. Data suggest that SCA2 lineages may tend to disappear eventually, due to strong anticipation phenomena. Whether or not the novel cases come from common haplotypes associated with a predisposition to further expansions is a question that needs to be addressed by future studies.

Body Mass Index Is Significantly Associated With Disease Severity in Spinocerebellar Ataxia Type 2 Patients.

BACKGROUND: Spinocerebellar ataxia type 2 is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Although weight loss has been associated with disease progression in several neurodegenerative conditions, it has been barely assessed in patients with spinocerebellar ataxia type 2. OBJECTIVE: The objective of this study was to test whether body mass index is altered in patients with spinocerebellar ataxia type 2 with varying expansion sizes from early to late disease stages. METHODS: A cross-sectional case-control study was performed, which included 222 clinically and molecularly diagnosed patients and 214 sex- and age-matched healthy individuals. ATXN2 genotypes and sex were considered as risk factors. Clinical outcomes included the body mass index, age at onset, disease duration, Scale for the Assessment and Rating of Ataxia score, disease stage, dysphagia, and progression rate. Multiple linear regression models were generated. RESULTS: Body mass index was significantly decreased in male patients, but not in female patients, relative to control subjects. In addition to sex, body mass index was significantly associated with age at onset and progression rate. Conversely, body mass index, along with repeat length in ATXN2 expanded alleles and disease duration, was associated with Scale for the Assessment and Rating of Ataxia score. In addition, body mass index, along with the age at onset and the repeat length in ATXN2 normal and expanded alleles, has a significant influence on progression rate. CONCLUSIONS: Body mass index might be a useful biomarker of disease severity, particularly in male patients with spinocerebellar ataxia type 2 in the context of nutritional interventions or clinical trials assessing the efficacy of promising new drugs. © 2021 International Parkinson and Movement Disorder Society.

Prodromal Spinocerebellar Ataxia Type 2 Subjects Have Quantifiable Gait and Postural Sway Deficits.

BACKGROUND: The search for valid preclinical biomarkers of cerebellar dysfunction is a key research goal for the upcoming era of early interventional approaches in spinocerebellar ataxias. This study aims to describe novel preclinical biomarkers of subtle gait and postural sway abnormalities in prodromal spinocerebellar ataxia type 2 (pre-SCA2). METHODS: Thirty pre-SCA2 patients and their matched healthy controls underwent quantitative assessments of gait and postural sway using a wearable sensor-based system and semiquantitative evaluation of cerebellar features by SARA (Scale for the Assessment and Rating of Ataxia) score. RESULTS: Quantitative analysis of natural gait showed a significantly larger variability of the swing period, toe-off angle and toe-out angle in pre-SCA2, and larger mean coronal and transverse ranges of motion of the trunk at the lumbar location and of the sagittal range of motion of the trunk at the sternum location compared to controls. During tandem gait, pre-SCA2 subjects showed larger lumbar, trunk, and arm ranges of motion than controls. Postural sway analysis showed excessive body oscillation that was increased in tandem stance. Overall, these abnormalities were detected in pre-SCA2 patients without clinical evidence of abnormalities in SARA. The toe-off angle and swing time variability were significantly correlated with the time to ataxia onset, whereas the toe-off angle and transverse range of motion at trunk position during tandem gait were significantly associated with the SARA score. CONCLUSIONS: This study demonstrates early alteration of gait and postural sway control in prodromal SCA2 using a wearable sensor-based system. This offers new pathophysiological hints into this early disease stage and provides novel potential biomarkers for future clinical trials. © 2020 International Parkinson and Movement Disorder Society.

EMG Rectification Is Detrimental for Identifying Abnormalities in Corticomuscular and Intermuscular Coherence in Spinocerebellar Ataxia Type 2.

Corticomuscular and intermuscular coherence (CMC, IMC) reflect connectivity between neuronal activity in the motor cortex measured by electroencephalography (EEG) and muscular activity measured by electromyography (EMG), or between activity in different muscles, respectively. There is an ongoing debate on the appropriateness of EMG rectification prior to coherence estimation. This work examines the effects of EMG rectification in CMC and IMC estimation in 20 spinocerebellar ataxia type 2 (SCA2) patients, 16 prodromal SCA2 gene mutation carriers, and 26 healthy controls during a repetitive upper or lower limb motor task. Coherence estimations were performed using the non-rectified raw EMG signal vs. the rectified EMG signal. EMG rectification decreases the level of significance of lower beta-frequency band CMC and IMC values in SCA2 patients and prodromal SCA2 mutation carriers vs. healthy controls, and also results in overall lower coherence values. EMG rectification is detrimental for beta-frequency band CMC and IMC estimation. One likely reason for this effect is distortion of coherence estimation in high-frequency signals, where the level of amplitude cancelation is high.

Testosterone Levels Are Decreased and Associated with Disease Duration in Male Spinocerebellar Ataxia Type 2 Patients.

Spinocerebellar ataxia type 2 (SCA2) is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Despite clinical and experimental evidence indicating the relevance of the gonadotropic axis to the prognosis and therapeutics for several late-onset neurodegenerative disorders, its functioning and association with disease severity have not been previously explored in SCA2. To assess serum levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), and their clinical relevance in SCA2 patients. A case-control study involving 94 Cuban SCA2 patients and 101 gender- and age-matched healthy controls was conducted. Testosterone, LH, and FSH serum levels were determined by radioimmunoassay or immunoradiometric assay systems. Clinical outcomes included age at onset, disease duration, Scale for the Assessment and Rating of Ataxia (SARA) score, and progression rate. Univariate general linear models were generated. Testosterone, LH, and FSH serum levels were significantly reduced in male SCA2 patients relative to control individuals. On average, there was a 35% reduction in testosterone levels in male patients versus male control individuals. Testosterone levels were associated with disease duration (r = 0.383; p = 0.025) and age at onset (r = 0.414; p = 0.011) in male SCA2 patients, but no association was observed between testosterone and CAG expansion size, SARA score, or progression rate. Testosterone levels might be a biomarker of disease progression in male SCA2 patients. Further studies are needed to explore the effects of low testosterone levels on non-motor symptoms, and to assess the potential of testosterone replacement therapy in male SCA2 patients.

Founder Effects of Spinocerebellar Ataxias in the American Continents and the Caribbean.

Spinocerebellar ataxias (SCAs) comprise a heterogeneous group of autosomal dominant disorders. The relative frequency of the different SCA subtypes varies broadly among different geographical and ethnic groups as result of genetic drifts. This review aims to provide an update regarding SCA founders in the American continents and the Caribbean as well as to discuss characteristics of these populations. Clusters of SCAs were detected in Eastern regions of Cuba for SCA2, in South Brazil for SCA3/MJD, and in Southeast regions of Mexico for SCA7. Prevalence rates were obtained and reached 154 (municipality of Báguano, Cuba), 166 (General Câmara, Brazil), and 423 (Tlaltetela, Mexico) patients/100,000 for SCA2, SCA3/MJD, and SCA7, respectively. In contrast, the scattered families with spinocerebellar ataxia type 10 (SCA10) reported all over North and South Americas have been associated to a common Native American ancestry that may have risen in East Asia and migrated to Americas 10,000 to 20,000 years ago. The comprehensive review showed that for each of these SCAs corresponded at least the development of one study group with a large production of scientific evidence often generalizable to all carriers of these conditions. Clusters of SCA populations in the American continents and the Caribbean provide unusual opportunity to gain insights into clinical and genetic characteristics of these disorders. Furthermore, the presence of large populations of patients living close to study centers can favor the development of meaningful clinical trials, which will impact on therapies and on quality of life of SCA carriers worldwide.

Involvement of the Auditory Pathway in Spinocerebellar Ataxia Type 7.

BACKGROUND: Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant disorder caused by a mutation in the ATXN7 gene. The involvement of the brainstem auditory pathway in pathogenesis of this disease has not been systematically assessed. AIM: To determine involvement of the brainstem auditory pathway in SCA7 patients and its relationship to clinical features of the disease. METHODS: In this case-control study, brainstem auditory-evoked potentials (BAEPs) were assessed in 12 SCA7 patients with clinical and molecular diagnosis, compared to 2 control groups of 16 SCA2 patients and 16 healthy controls. RESULTS: SCA7 patients exhibited significant prolongation of I-wave and III-wave latencies, whereas SCA2 patients showed increased latencies for III and V waves and I-III interpeak interval. SCA7 patients with larger I-wave latencies exhibited larger CAG repeats, earlier onset age, and higher SARA scores, but in SCA2 cases, these were not observed. CONCLUSIONS: BAEP tests revealed functional involvement of the auditory pathway in SCA7 (mainly at) peripheral portions, which gave new insights into the disease physiopathology different from SCA2 and may unravel distinct pathoanatomical effects of polyQ expansions in the central nervous system. SIGNIFICANCE: These findings offer important insights into the distinctive disease mechanisms in SCA7 and SCA2, which could be useful for differential diagnosis and designing specific precision medicine approaches for both conditions.

Neurorehabilitation Improves the Motor Features in Prodromal SCA2: A Randomized, Controlled Trial.

BACKGROUND: The search for early interventions is a novel approach in spinocerebellar ataxias, but there are few studies supporting this notion. This article aimed to assess the efficacy of neurorehabilitation treatment in prodromal spinocerebellar ataxia type 2. METHODS: Thirty spinocerebellar ataxia type 2 preclinical carriers were enrolled in a randomized, controlled trial using neurorehabilitation. The intervention in the treated group was 4 hours per day, 5 days per week for 12 weeks, emphasizing static balance, gait, and limb coordination. The control group did not receive rehabilitation. The primary outcome measure was the time for 5-m tandem gait over the floor. Secondary outcomes included other timed tests with increased motor complexity, as well as the scores of the SARA and the Inventory of Non-ataxia Symptoms. RESULTS: The times for 5-m tandem gait over the floor and the mattress were significantly reduced only in the rehabilitated group. Moreover, the times upholding the tandem stance over a mattress and the seesaw were notably increased only in this group. Likewise, the finger-nose and the heel-shin tests were improved in the rehabilitated group alone. The SARA score and the count of nonataxia symptoms were unchanged. CONCLUSIONS: This rehabilitation program improves the subtle gait, postural and coordinative deficits in prodromal spinocerebellar ataxia type 2, which provided novel hints about the preservation of motor learning and neural plasticity mechanisms in early disease stages, leading chances for other interventional approaches in this and other spinocerebellar ataxias. © 2019 International Parkinson and Movement Disorder Society.