Ataxia Rating Scales—Psychometric Profiles, Natural History and Their Application in Clinical Trials

Scale for the assessment and rating of ataxia: a live e-version

BACKGROUND

Measuring ataxia severity is primarily conducted in-person using tests such as the Scale for the Assessment and Rating of Ataxia (SARA). However, given the motor and cognitive impairments of people with cerebellar ataxia (PwA), there are major limitations in ensuring the assessment is accessible and scalable. We aimed to develop and validate a novel test, enabling the remote assessment of ataxia severity, SARA-Le (SARA Live e-version).

METHODS

SARA-Le is a structured step-by-step test for administering the SARA through video conferencing. In two experiments, we administered SARA-Le to 106 PwA. In Experiment 1 (n = 23), we assessed concurrent validity by comparing SARA-Le and in-person SARA scores administered by an independent neurologist. In addition, we evaluated associations between nine gait measures and both SARA and SARA-Le scores. In Experiment 2 (n = 83), we assessed the efficacy, internal consistency, and correlations between SARA-Le and other related measures.

RESULTS

First, we found a high correlation (r = 0.89, P = 0.001) between SARA-Le and in-person SARA scores, supporting convergent validity. Second, SARA-Le and SARA scores were both similarly associated with the nine gait measures, supporting construct validity. Third, SARA-Le's Cronbach's alpha was very high (0.831), supporting internal consistency. Fourth, SARA-Le scores exhibited a positive correlation with disease duration (r = 0.44, P < 0.001), and a negative correlation with MoCA scores (r = - 0.27, P = 0.007), supporting construct validity.

CONCLUSIONS

SARA-Le can serve as a remote technology-based protocol, improving the accessibility and scalability of ataxia severity evaluation.

Validation of the Italian Version of the Scale for the Assessment and Rating of Ataxia (SARA) in Multiple Sclerosis: A Cross-Sectional Study

Multiple sclerosis (MS) is a chronic neurodegenerative disorder often associated with cerebellar ataxia. Accurate assessment of ataxia is crucial for monitoring disease progression and guiding rehabilitation. The Scale for the Assessment and Rating of Ataxia (SARA) is a clinician-reported outcome measure (ClinRO) designed to evaluate ataxia severity. This study aimed to translate, culturally adapt, and validate the Italian version of SARA in individuals with MS. This study follows a cross-sectional design and was conducted at the Neurorehabilitation Unit of Sapienza University of Rome. The translation followed ISPOR and ISOQOL guidelines to ensure linguistic and cultural equivalence. Psychometric properties evaluation included internal consistency (Cronbach's alpha), test-retest reliability (intraclass correlation coefficient [ICC]), construct validity (correlation with Berg Balance Scale [BBS], Mini-Balance Evaluation Systems Test [Mini-BESTest], and Timed Up and Go [TUG] test), and cross-cultural validity. Seventy-five MS patients (EDSS ≤ 6.5) were recruited. The Italian SARA version demonstrated excellent internal consistency (Cronbach's alpha = 0.855) and test-retest reliability (ICC = 0.993). Strong negative correlations were found with BBS (r = -0.838, p < 0.001) and Mini-BESTest (r = -0.767, p < 0.001), supporting construct validity. Significant differences emerged based on age, employment status, and EDSS scores. The Italian SARA is a valid and reliable tool for assessing ataxia severity in MS. Its strong psychometric properties support its use in clinical and research settings. Future studies should explore its responsiveness to rehabilitation interventions.

Contrastive Learning Model for Wearable-based Ataxia Assessment

Objective

Frequent and objective assessment of ataxia severity is essential for tracking disease progression and evaluating the effectiveness of potential treatments. Wearable-based assessments have emerged as a promising solution. However, existing methods rely on inertial data features directly correlated with subjective and coarse clinician-evaluated rating scales, which serve as imperfect gold standards. This approach may introduce biases and restrict flexibility in feature design. To address these limitations, this study introduces a novel contrastive learning-based model that leverages motor severity differences in wearable inertial data to learn relevant features.

Methods

The model was trained on inertial data collected from 87 individuals with diagnostically heterogeneous ataxias and 44 healthy participants performing the finger-to-nose task. A pairwise contrastive loss function was proposed to learn representations capturing relative differences in ataxia severity, which were evaluated through downstream regression and classification tasks.

Results

The learned features demonstrated strong cross-sectional (r = 0.84) and longitudinal (r = 0.68) associations with clinical scores and robust measurement reliability (intraclass correlation coefficient = 0.96). Additionally, the model exhibited strong known-group validity, distinguishing between ataxia and healthy phenotypes with an area under the receiver operating characteristic curve of 0.95.

Conclusion

The proposed contrastive model captures robust representations of disease severity with reduced reliance on clinical scales, outperforming state-of-the-art methods that derive features directly from clinical scores.

Significance

Combining wearable sensors with contrastive learning enables a more objective, scalable, and frequent method for assessing ataxia severity, with the potential to enhance patient monitoring and improve clinical trial efficiency.

Longitudinal Changes in Patient- and Clinical-Reported Outcomes in Early Spinocerebellar Ataxia Types 1, 2, 3, and 6 from the IDEA Study

BACKGROUND

Clinical outcomes assessments (COAs) in spinocerebellar ataxia (SCA) need to be standardized, ataxia-specific, sensitive to change, clinically relevant, and meaningful to patients.

OBJECTIVES

To evaluate the longitudinal 1- and 2-year performances of different patient reported outcomes, including the Patient Reported Outcome Measure of Ataxia (PROM-Ataxia), and clinician reported outcomes, including FARS and SARA, in those with early manifest symptoms of SCA 1, 2, 3, and 6.

METHODS

We studied 53 patients with early stage SCA1-3 and SCA6 from The Instrumented Data Exchange for Ataxia Study and 24 age-matched healthy controls. Participants were seen every 6 months for 2 years. Mixed models were used to estimate change over 12- and 24-months of follow-up. Changes on the FARS-FS and PGI-C were used as anchors to estimate meaningful changes.

RESULTS

Among persons with SCA, mean age was 48.7 years and mean SARA score was 9.3. Few measures showed statistically significant changes at 12 months. At 24-months, the FARS-ADL, PROM-Ataxia total, PROM-Ataxia physical, and PROM-Ataxia ADL scores showed the strongest associations of change.

CONCLUSIONS

Patient reported or derived outcome measures, such as FARS-ADL and ADL sub domain of the PROM-Ataxia, can capture longitudinal change in patients' symptom experience over a 2-year period and its impact on daily activities, even in those with early disease. More work is needed to identify outcomes that reliably capture change earlier.

Cross-Cultural Translation and Validation of the Thai Version of the Scale for the Assessment and Rating of Ataxia (SARA-TH)

OBJECTIVE

To culturally adapt the original English Scale for the Assessment and Rating of Ataxia to Thai (SARA-TH) and to evaluate the reliability and validity of the SARA-TH in assessing ataxia in acute ischemic stroke or transient ischemic attack (TIA) patients, as assessed by three healthcare professionals.

METHODS

The SARA underwent translation and cross-cultural adaptation to Thai according to established guidelines. Reliability (e.g., internal consistency, intrarater reliability, interrater reliability) and validity (e.g., content validity, convergent validity) were assessed in a sample of 50 participants with ataxia after acute ischemic stroke or TIA. Spearman correlation analysis was used to examine the relationships between the SARA-TH and the Barthel Index (BI-TH), the National Institutes of Health Stroke Scale (NIHSS-TH), and the International Cooperative Ataxia Rating Scale (ICARS) to assess convergent validity. Interrater and intrarater reliability among experienced and novice neurologists, physiotherapists, and occupational therapists were assessed using weighted kappa.

RESULTS

The SARA-TH demonstrated good comprehension and exhibited no significant floor or ceiling effects. It showed excellent internal consistency (Cronbach's α≥0.776). Significant correlations were found between the SARA-TH score and the BI-TH score (rs=-0.743 to -0.665), NIHSS- TH score (rs=0.404-0.513), and ICARS score (rs=0.859-0.917). The intrarater reliability for each rater ranged from 0.724 to 1.000 (p<0.01), and the interrater reliability varied from 0.281 to 0.927 (p<0.01).

CONCLUSION

The SARA-TH has excellent internal consistency, validity, and intrarater reliability, as well as acceptable interrater reliability among health professionals with varying levels of experience. It is recommended for assessing ataxia severity in individuals following acute ischemic stroke or TIA.

The importance of synthetic pharmacotherapy for recessive cerebellar ataxias

INTRODUCTION

The last decade has witnessed major breakthroughs in identifying novel genetic causes of hereditary ataxias, deepening our understanding of disease mechanisms, and developing therapies for these debilitating disorders.

AREAS COVERED

This article reviews the currently approved and most promising candidate pharmacotherapies in relation to the known disease mechanisms of the most prevalent autosomal recessive ataxias. Omaveloxolone is an Nrf2 activator that increases antioxidant defense and was recently approved for treatment of Friedreich ataxia. Its therapeutic effect is modest, and further research is needed to find synergistic treatments that would halt or reverse disease progression. Promising approaches include upregulation of frataxin expression by epigenetic mechanisms, direct protein replacement, and gene replacement therapy. For ataxia-telangiectasia, promising approaches include splice-switching antisense oligonucleotides and small molecules targeting oxidative stress, inflammation, and mitochondrial function. Rare recessive ataxias for which disease-modifying therapies exist are also reviewed, emphasizing recently approved therapies. Evidence supporting the use of riluzole and acetyl-leucine in recessive ataxias is discussed.

EXPERT OPINION

Advances in genetic therapies for other neurogenetic conditions have paved the way to implement feasible approaches with potential dramatic benefits. Particularly, as we develop effective treatments for these conditions, we may need to combine therapies, consider newborn testing for pre-symptomatic treatment, and optimize non-pharmacological approaches.

Neurocognitive Impairment in Patients With Ataxia Telangiectasia and Their Unaffected Parents: Is It Similar?

BACKGROUND

Ataxia telangiectasia (AT) is a genetic multisystemic disorder affecting the nervous system. Data on neurocognitive functioning in AT are limited and focused on patients at various stages of disease. Because of the genetic nature of the disorder, parents of patients may also display subtle neurological problems. This study aimed to evaluate neurocognitive functioning in patients with AT and their unaffected parents.

METHODS

The study included 26 patients with AT and 41 parents among which 13 patients and 18 parents were evaluated with neurocognitive tests. Clinical and radiological data were reviewed retrospectively. Data were analyzed with descriptive statistics.

RESULTS

The median ages of patients and parents were 12.5 years (interquartile range [IQR] = 9.5) and 38.0 years (IQR = 12.0), respectively. Median intelligence quotients were 62.0 (IQR = 21.3) and 82.5 (IQR = 16.8), respectively, for patients and parents. Rates of intellectual disability for patients and parents were 100.0% and 83.3%, respectively. Areas of impairment in patients in decreasing order of frequency were motor skills, visual perception/memory, visual-manual coordination, spontaneous/focused and sustained attention (100.0% for each), social judgment, as well as vocabulary and arithmetic skills (75.0% for each). Areas of impairment in unaffected parents in decreasing order of frequency were visual-manual coordination (77.8%), working memory (76.5%), and visual perception and motor skills (66.7% for each).

CONCLUSION

Intellectual disabilities, visual-spatial disabilities, and reduced visual-motor coordination seem to be similar in patients with AT and their parents. These results should be replicated with larger samples from multiple centers and may form putative cognitive endophenotypes for the disorder.

Consensus Recommendations for Clinical Outcome Assessments and Registry Development in Ataxias: Ataxia Global Initiative (AGI) Working Group Expert Guidance

To accelerate and facilitate clinical trials, the Ataxia Global Initiative (AGI) was established as a worldwide research platform for trial readiness in ataxias. One of AGI's major goals is the harmonization and standardization of outcome assessments. Clinical outcome assessments (COAs) that describe or reflect how a patient feels or functions are indispensable for clinical trials, but similarly important for observational studies and in routine patient care. The AGI working group on COAs has defined a set of data including a graded catalog of COAs that are recommended as a standard for future assessment and sharing of clinical data and joint clinical studies. Two datasets were defined: a mandatory dataset (minimal dataset) that can ideally be obtained during a routine clinical consultation and a more demanding extended dataset that is useful for research purposes. In the future, the currently most widely used clinician-reported outcome measure (ClinRO) in ataxia, the scale for the assessment and rating of ataxia (SARA), should be developed into a generally accepted instrument that can be used in upcoming clinical trials. Furthermore, there is an urgent need (i) to obtain more data on ataxia-specific, patient-reported outcome measures (PROs), (ii) to demonstrate and optimize sensitivity to change of many COAs, and (iii) to establish methods and evidence of anchoring change in COAs in patient meaningfulness, e.g., by determining patient-derived minimally meaningful thresholds of change.

[Scale for the assessment and rating of ataxia (SARA): translation and cultural adaptation to German-speaking areas]

BACKGROUND/OBJECTIVE

The scale for the assessment and rating of ataxia (SARA) is a feasible assessment for the classification and evaluation of therapeutic interventions. In order to provide access to the SARA in German, the aim of this work was to translate the SARA into German and to adapt it according to international guidelines for German-speaking countries.

METHOD

The process involved six steps. The comprehensibility of the scale was assessed using interviews with potential users.

RESULTS

A total of nine physiotherapists and six physicians working in various clinical settings were interviewed, seven of them worked in Germany and four each in Austria and Switzerland. The interviews led to a refined version of the translation. The comprehensibility testing revealed no country-specific differences.

CONCLUSION

A German version of the SARA authorized by the co-author of the original publication, is now available. The results provide methodological insights into the translation process of observation-based standardized assessments.

The Scale for Assessment and Rating of Ataxia Is Reliable and Valid in the Telehealth Setting for Patients With Cerebellar Ataxia

OBJECTIVE

Health care has increasingly expanded into a hybrid in-person/telehealth model. Patients with a variety of health conditions, including cerebellar ataxia, have received virtual health evaluations; however, it remains unknown whether some outcome measures that clinicians utilize in the telehealth setting are reliable and valid. The goal of this project is to evaluate the psychometric properties of the Scale for Assessment and Rating of Ataxia (SARA) for patients with cerebellar ataxia in the telehealth setting.

METHODS

Nineteen individuals with cerebellar impairments were recruited on a voluntary basis. Participants completed 2 30-minute testing sessions during which a clinical examination and the SARA were performed. One session was performed in person, and the other session was assessed remotely. Outcome measure performance was video recorded in both environments and independently scored by 4 additional raters with varying levels of clinical experience (ranging from 6 months to 29 years). Concurrent validity was assessed with the Spearman rank order correlation coefficient (α < .05), comparing the virtual SARA scores to their gold standard in-person scores. Interrater reliability was evaluated with the intraclass correlation coefficient (ICC) (2,4) (α < .05).

RESULTS

Fourteen of the 19 participants completed both in-person and telehealth SARA evaluations. We found that the in-person SARA and the telehealth SARA have large concurrent validity (Spearman rho significant at the 2-tailed α of .01 = 0.90; n = 14). Additionally, raters of varying years of experience had excellent interrater reliability for both the in-person SARA (ICC [2,4] = 0.97; n = 19) and the telehealth SARA (ICC [2,4] = 0.98; n = 14).

CONCLUSION

Our results show that the telehealth SARA is comparable to the in-person SARA. Additionally, raters of varying years of clinical experience were found to have excellent interrater reliability scores for both remote and in-person SARA evaluations.

IMPACT

Our study shows that the SARA can be used in the telehealth setting for patients with ataxia.

Efficacy and Safety of Repetitive Transcranial Magnetic Stimulation in Cerebellar Ataxia: a Systematic Review and Meta-analysis

Cerebellar ataxia(CA) is defined as a degenerative disease of the nervous system. Repetitive transcranial magnetic stimulation (rTMS) has been a promising treatment for neurological and psychiatric diseases. Hence, to find out whether cerebellar rTMS impacts CA as a potential therapy, we performed a systematic review and meta-analysis. Qualified studies through a systematic search were retrieved for randomized controlled trials (RCTs) using acknowledged databases. Review Manager 5.4 software was employed to synthesize the data. A total of seven studies were identified as eligible and included in the quantitative review. Comparing real and sham-rTMS interventions, the utilization of rTMS on cerebellum improved the scale for the assessment and rating of ataxia (SARA) (SMD - 0.87, 95% CI - 1.41 to - 0.34; P = 0.001; I2 = 62%), the International Cooperative Ataxia Rating Scale (ICARS) (SMD - 1.06, 95% CI - 1.47 to - 0.64; P < 0.00001; I2 = 0%) and Berg balance Scale (BBS) (SMD 0.76, 95% CI 0.33 to 1.19; P = 0.0005; I2 = 39%). The subgroup analysis demonstrated high-frequency of rTMS had a positive effect (SMD - 1.28, 95% CI - 1.82 to - 0.74; P < 0.00001; I2 = 0%). For the safety, the incidence of adverse events between the two groups was not significantly different (OR 1.73, 95% CI 0.55 to 5.46; P = 0.35; I2 = 0%). In conclusion, this meta-analysis provided limited evidence, suggesting a possible strategy that rTMS over the cerebellum could be a viable therapy for symptoms associated with CA. Besides, rTMS intervention was well-attended and did not result in unanticipated negative effects.

French Translation and Cross-cultural Adaptation of the Scale for the Assessment and Rating of Ataxia

The Scale for the Assessment and Rating of Ataxia (SARA) is a widely used scale for assessing the severity of ataxia in clinics, natural history studies, and treatment trials worldwide. However, no French translation with validated cross-cultural adaptation is available. This study aimed to translate and adapt the SARA into French. The translation process was conducted according to the ISPOR guidelines for the translation and cultural adaptation process for patient-reported outcomes. A total of five translators, an expert committee, and two physiotherapists took part in the process to assess and ensure comprehension and language equivalences of the final French version. A few misinterpretations were pointed out during the translation process and were changed accordingly by the translation team. The French version of the SARA is ready to be used in clinical and research settings with French-speaking populations living with ataxia.

Ataxia Rating Scales Reveal Increased Scores in Very Preterm Born 5-6-Year-Old Preschool Children and Young Adults

The aim of this study is to investigate whether scores in ataxia rating scales (ARS) are different in very preterm (VP) preschool and adult participants compared to term controls. This is a case-control study. Sixty VP children (years: 5.5-6.5; gestational age: 23.9-31.7 weeks) and 56 VP adults (years: 17.8-27.9; gestational age: 23.3-32.0 weeks) without major cerebral lesions participated in the study; 60-age and sex-matched term children and 64 term adults for comparison were used in the study intervened with the assessment with International Cooperative Ataxia Rating Scale (ICARS) and Scale for Assessment and Rating of Ataxia (SARA). Main outcome measures are primary outcome: total icars and sara scores in preterm (vp) participants versus controls. Results showed that VP children showed significantly higher total ICARS (M 15.98, SD 6.29, range 4.0-32.0; p < .001) and SARA scores (M 6.5, SD 2.53, range 1.0-15.0; p < .001) than controls (ICARS: M 9.17, SD 3.88, range 2.0-20.0; SARA: M 3.51, SD 1.54, range 1.0-8.0). VP adults also showed significantly higher total ICARS (M 1.0, SD 1.99, range 0.0-11.0; p < .001) and SARA scores (M 0.54, SD 1.08, range 0.0-6.0; p < .001) than controls (ICARS: M 0.11, SD 0.44, range 0.0-2.0; SARA: M 0.04, SD 0.18, range 0.0-1.0). In conclusion, VP children showed significantly higher scores in ARS than controls. These differences were also present in VP adults, suggesting that deficits likely prevail until adulthood. ARS are a time and cost-effective method to screen for difficulties in coordination and balance in a patient group at risk.

Neurological and cerebellar soft signs in bipolar disorder: The role of staging, type and history of psychotic symptoms

AIM

Bipolar disorder (BD) patients show neurological abnormalities in form of neurological and cerebellar soft signs (NSS and CSS). NSS represents heterogeneous group of symptoms representing i.a. deficits of motor coordination, sequencing of complex motor acts and sensory integration. CSS were introduced as group of the neurological deficits of posture, gait, kinetic functions, eye movements and speech, associated more specifically to cerebellar abnormalities than NSS. Studies show significant effect size variability of those symptoms in BD group suggesting the existence of differing subpopulations. The aim of our study was to evaluate the effect of BD type, stage and the history of psychotic symptoms (HoPS) on the severity of CSS and NSS as none of the previous studies had verified the role of those categories.

METHODS

This study involved 181 participants: 116 euthymic BD patients (66 BD I, 50 BD II) and 65 healthy controls (HC). CSS was assessed with the International Cooperative Ataxia Rating Scale and NSS with Neurological Evaluation Scale. Patients were divided into early and late stage of the disorder according to Kapczinski's criteria. Rater was blind to patients' stage, type and HoPS.

RESULTS

Staging was related to vast majority of CSS and NSS scores. HoPS was related to oculomotor deficits. The effect of BD type was the least significant. Late stage BD showed more severe CSS and NSS than HC in every measure. There were no differences between early stage BD and HC, apart of posture and gait disturbances. Except of sensory integration scores, late stage BD showed higher CSS and NSS rates than early stage patients.

CONCLUSION

In this hitherto the largest study of neurological abnormalities in BD we have shown significant role of staging in CSS and NSS severity. Progression criteria based on inter-episode psychosocial functioning may stand as unrecognised factor responsible for variability observed in previous studies evaluating neurological abnormalities in BD. Our study suggests that in clinical practice NSS and CSS may be potentially used as easy-to-assess biological marker of BD staging. Observed severity of neurological impairments of BD patients may more likely correspond to the disease progression than to BD type and HoPS.

A Proof of Concept Combined Using Mixed Reality for Personalized Neurorehabilitation of Cerebellar Ataxic Patients

BACKGROUND

Guidelines for degenerative cerebellar ataxia neurorehabilitation suggest intensive coordinative training based on physiotherapeutic exercises. Scientific studies demonstrate virtual exergaming therapeutic value. However, patient-based personalization, post processing analyses and specific audio-visual feedbacks are not provided. This paper presents a wearable motion tracking system with recording and playback features. This system has been specifically designed for ataxic patients, for upper limbs coordination studies with the aim to retrain movement in a neurorehabilitation setting. Suggestions from neurologists and ataxia patients were considered to overcome the shortcomings of virtual systems and implement exergaming.

METHODS

The system consists of the mixed-reality headset Hololens2 and a proprietary exergaming implemented in Unity. Hololens2 can track and save upper limb parameters, head position and gaze direction in runtime.

RESULTS

Data collected from a healthy subject are reported to demonstrate features and outputs of the system.

CONCLUSIONS

Although further improvements and validations are needed, the system meets the needs of a dynamic patient-based exergaming for patients with cerebellar ataxia. Compared with existing solutions, the mixed-reality system is designed to provide an effective and safe therapeutic exergaming that supports both primary and secondary goals of an exergaming: what a patient should do and how patient actions should be performed.

Progression of Clinical and Eye Movement Markers in Preataxic Carriers of Machado-Joseph Disease

BACKGROUND

Little is known about preclinical stages of Machado-Joseph disease, a polyglutamine disorder characterized by progressive adult-onset ataxia.

OBJECTIVE

We aimed to describe the longitudinal progression of clinical and oculomotor variables in the preataxic phase of disease.

METHODS

Carriers and noncarriers were assessed at three visits. Preataxic carriers (Scale for Assessment and Rating of Ataxia score < 3) expected to start ataxia in ≤4 years were considered near onset (PAN). Progressions of ataxic and preataxic carriers, considering status at the end of the study, were described according to the start (or its prediction) of gait ataxia (TimeToAfterOnset) and according to the study time.

RESULTS

A total of 35 ataxics, 38 preataxics, and 22 noncarriers were included. The "TimeToAfterOnset" timeline showed that Neurological Examination Scale for Spinocerebellar Ataxias (NESSCA; effect size, 0.09), Inventory of Non-Ataxia Symptoms (INAS0.07), and the vestibulo-ocular reflex gain (0.12) progressed in preataxic carriers, and that most slopes accelerate in PAN, turning similar to those of ataxics. In the study time, NESSCA (1.36) and vertical pursuit gain (1.17) significantly worsened in PAN, and 6 of 11 PANs converted to ataxia. For a clinical trial with 80% power and 2-year duration, 57 PANs are needed in each study arm to detect a 50% reduction in the conversion rate.

CONCLUSIONS

NESSCA, INAS, vestibulo-ocular reflex, and vertical pursuit gains significantly worsened in the preataxic phase. The "TimeToAfterOnset" timeline unveiled that slopes of most variables are small in preataxics but increase and reach the ataxic slopes from 4 years before the onset of ataxia. For future trials in preataxic carriers, we recommend recruiting PANs and using the conversion rate as the primary outcome. © 2022 International Parkinson and Movement Disorder Society.

Ataxia Rating Scales: Content Analysis by Linking to the International Classification of Functioning, Disability and Health

Ataxia management is mainly based on rehabilitation, symptomatic management, and functional improvement. Therefore, it is important to comprehensively assess ataxic symptoms and their impact on function. Recently, the movement disorders society recommended four generic ataxia rating scales: scale for assessment and rating of ataxia (SARA), international cooperative ataxia rating scales, Friedreich's ataxia rating scale (FARS), and unified multiple system atrophy rating scale (UMSARS). The aim of the study was to analyze and compare the content of the recommended ataxia rating scales by linking them to the international classification of functioning, disability and health (ICF). A total of 125 meaningful concepts from 93 items of the four included scales were linked to 57 different ICF categories. The ICF categories were distributed in body structure (n = 8), body function (n = 26), activity and participation (n = 20), and environmental factors (n = 3) components. UMSARS and FARS were the only ones that have addressed the body structure or environmental factors component. The content analysis of ataxia rating scales would help clinicians and researchers select the most appropriate scale and understand ataxic symptoms and their impact on function. It seems that SARA is the optimal scale for rapid assessment of ataxia or in busy clinical settings. UMSARS or FARS are more appropriate for the investigating the impact of ataxia on overall health, and monitoring ataxia progression and disability.

The progression rate of spinocerebellar ataxia type 3 varies with disease stage

BACKGROUND

In polyglutamine (polyQ) diseases, the identification of modifiers and the construction of prediction model for progression facilitate genetic counseling, clinical management and therapeutic interventions.

METHODS

Data were derived from the longest longitudinal study, with 642 examinations by International Cooperative Ataxia Rating Scale (ICARS) from 82 SCA3 participants. Using different time scales of disease duration, we performed multiple different linear, quadratic and piece-wise linear growth models to fit the relationship between ICARS scores and duration. Models comparison was employed to determine the best-fitting model according to goodness-of-fit tests, and the analysis of variance among nested models.

RESULTS

An acceleration was detected after 13 years of duration: ICARS scores progressed 2.445 (SE: 0.185) points/year before and 3.547 (SE: 0.312) points/year after this deadline. Piece-wise growth model fitted better to studied data than other two types of models. The length of expanded CAG repeat (CAGexp) in ATXN3 gene significantly influenced progression. Age at onset of gait ataxia (AOga), a proxy for aging process, was not an independent modifier but affected the correlation between CAGexp and progression. Additionally, gender had no significant effect on progression rate of ICARS. The piece-wise growth models were determined as the predictive models, and ICARS predictions from related models were available.

CONCLUSIONS

We first confirmed that ICARS progressed as a nonlinear pattern and varied according to different stages in SCA3. In addition to ATXN3 CAGexp, AOga or aging process regulated the progression by interacting with CAGexp.

A Novel SCA3 Knock-in Mouse Model Mimics the Human SCA3 Disease Phenotype Including Neuropathological, Behavioral, and Transcriptional Abnormalities Especially in Oligodendrocytes

Spinocerebellar ataxia type 3 is the most common autosomal dominant inherited ataxia worldwide, caused by a CAG repeat expansion in the Ataxin-3 gene resulting in a polyglutamine (polyQ)-expansion in the corresponding protein. The disease is characterized by neuropathological, phenotypical, and specific transcriptional changes in affected brain regions. So far, there is no mouse model available representing all the different aspects of the disease, yet highly needed for a better understanding of the disease pathomechanisms. Here, we characterized a novel Ataxin-3 knock-in mouse model, expressing a heterozygous or homozygous expansion of 304 CAACAGs in the murine Ataxin-3 locus using biochemical, behavioral, and transcriptomic approaches. We compared neuropathological, and behavioral features of the new knock-in model with the in SCA3 research mostly used YAC84Q mouse model. Further, we compared transcriptional changes found in cerebellar samples of the SCA3 knock-in mice and post-mortem human SCA3 patients. The novel knock-in mouse is characterized by the expression of a polyQ-expansion in the murine Ataxin-3 protein, leading to aggregate formation, especially in brain regions known to be vulnerable in SCA3 patients, and impairment of Purkinje cells. Along these neuropathological changes, the mice showed a reduction in body weight accompanied by gait and balance instability. Transcriptomic analysis of cerebellar tissue revealed age-dependent differential expression, enriched for genes attributed to myelinating oligodendrocytes. Comparing these changes with those found in cerebellar tissue of SCA3 patients, we discovered an overlap of differentially expressed genes pointing towards similar gene expression perturbances in several genes linked to myelin sheaths and myelinating oligodendrocytes.

Relationship between neurological and cerebellar soft signs, and implicit motor learning in schizophrenia and bipolar disorder

BACKGROUND

Schizophrenia (SZ) and bipolar disorder (BD) patients share deficits in motor functions in the form of neurological (NSS) and cerebellar soft signs (CSS), and implicit motor learning disturbances. Here, we use cluster analysis method to assess (1) the relationship between those abnormalities in SZ and BD and (2) the differences between those groups.

METHODS

33 SZ patients, 33 BD patients as well as 31 healthy controls (HC) took part in the study. We assessed CSS with the International Cooperative Ataxia Rating Scale (ICARS) and NSS with the Neurological Evaluation Scale (NES). Implicit motor learning was evaluated with the Serial Reaction Time Task (SRTT). Participants were divided into clusters (Ward's method) based on the mean response time and mean error rate in SRTT. The difference in ICARS and NES scores, and SRTT variables between clusters were evaluated. We have measured associations between SRTT parameters and both ICARS and NES total scores and subscores.

RESULTS

Cluster analysis based on the SRTT parameters allowed to extract three clusters. Those were characterized by the increasing disruption of motor functioning (psychomotor retardation, the severity of NSS and CSS) regardless of the diagnosis. Cluster 1 covered almost all of HC and was characterized by faster reaction times and small number of errors. BD and SZ patients represented in cluster 1, although fully functional in performing the SRTT, showed higher rates of NSS and CSS. Patients with BD and SZ were set apart in clusters 2 and 3 in a similar proportion. Cluster 2 presented significantly slower reaction times but with the comparable number of errors to cluster 1. Cluster 3 consisted of participants with normal or decreased reaction time and significantly increased number of errors. None of the clusters were predominantly composed of the patients representing one psychiatric diagnosis.

CONCLUSIONS

To our best knowledge, we are presenting the first data indicating the relationship between implicit motor learning and NSS and CSS in SZ and BD patients' groups. Lack of clusters predominantly represented by patients with the diagnosis of SZ or BD may refer to the model of schizophrenia-bipolar disorder boundary, pointing out the similarities between those two disorders.

Safety and Efficacy of Acetyl-DL-Leucine in Certain Types of Cerebellar Ataxia: The ALCAT Randomized Clinical Crossover Trial

IMPORTANCE

Cerebellar ataxia is a neurodegenerative disease impairing motor function characterized by ataxia of stance, gait, speech, and fine motor disturbances.

OBJECTIVE

To investigate the efficacy, safety, and tolerability of the modified essential amino acid acetyl-DL-leucine in treating patients who have cerebellar ataxia.

DESIGN, SETTING, AND PARTICIPANTS

The Acetyl-DL-leucine on Cerebellar Ataxia (ALCAT) trial was an investigator-initiated, multicenter, double-blind, randomized, placebo-controlled, clinical crossover trial. The study was conducted at 7 university hospitals in Germany and Austria between January 25, 2016, and February 17, 2017. Patients were aged at least 18 years and diagnosed with cerebellar ataxia of hereditary (suspected or genetically confirmed) or nonhereditary or unknown type presenting with a total score of at least 3 points on the Scale for the Assessment and Rating of Ataxia (SARA). Statistical analysis was performed from April 2018 to June 2018 and January 2020 to March 2020.

INTERVENTIONS

Patients were randomly assigned (1:1) to receive acetyl-DL-leucine orally (5 g per day after 2 weeks up-titration) followed by a matched placebo, each for 6 weeks, separated by a 4-week washout, or vice versa. The randomization was done via a web-based, permuted block-wise randomization list (block size, 2) that was stratified by disease subtype (hereditary vs nonhereditary or unknown) and site.

MAIN OUTCOMES AND MEASURES

Primary efficacy outcome was the absolute change of SARA total score from (period-dependent) baseline to week 6.

RESULTS

Among 108 patients who were randomly assigned to sequence groups (54 patients each), 55 (50.9%) were female; the mean (SD) age was 54.8 (14.4) years; and the mean (SD) SARA total score was 13.33 (5.57) points. The full analysis set included 105 patients (80 patients with hereditary, 25 with nonhereditary or unknown cerebellar ataxia). There was no evidence of a difference in the mean absolute change from baseline to week 6 in SARA total scores between both treatments (mean treatment difference: 0.23 points [95% CI, -0.40 to 0.85 points]).

CONCLUSIONS AND RELEVANCE

In this large multicenter, double-blind, randomized, placebo-controlled clinical crossover trial, acetyl-DL-leucine in the investigated dosage and treatment duration was not superior to placebo for the symptomatic treatment of certain types of ataxia. The drug was well tolerated; and ALCAT yielded valuable information about the duration of treatment periods and the role of placebo response in cerebellar ataxia. These findings suggest that further symptom-oriented trials are needed for evaluating the long-term effects of acetyl-DL-leucine for well-defined subgroups of cerebellar ataxia.

TRIAL REGISTRATION

EudraCT 2015-000460-34.

Effects of Anodal Cerebellar Transcranial Direct Current Stimulation on Movements in Patients with Cerebellar Ataxias: A Systematic Review

Cerebellar transcranial direct current stimulation (cerebellar tDCS) is a promising therapy for cerebellar ataxias and has attracted increasing attention from researchers and clinicians. A timely systematic review focusing on randomized sham-controlled trials and repeated measures studies is warranted. This study was to systematically review existing evidence regarding effects of anodal cerebellar tDCS on movements in patients with cerebellar ataxias. The searched databases included Web of Science, MEDLINE, PsycINFO, CINAHL, EMBASE, Cochrane Library, and EBSCOhost. Methodological quality of the selected studies was assessed using the Physiotherapy Evidence Database scale. Five studies with 86 patients were identified. Among these, four studies showed positive effects of anodal cerebellar tDCS. Specifically, anodal cerebellar tDCS decreased disease severity and improved finger dexterity and quality of life in patients, but showed incongruent effects on gait control and balance, which may be due to heterogeneity of research participants and choices of measures. The protocols of anodal cerebellar tDCS that improved movements in patients commonly placed the anode over the whole cerebellum and provided ten 2-mA 20-min stimulation sessions. The results may show preliminary evidence that anodal cerebellar tDCS is beneficial to reducing disease severity and improving finger dexterity and quality of life in patients, which lays the groundwork for future studies further examining responses in the cerebello-thalamo-cortical pathway. An increase in sample size, the use of homogeneous patient groups, exploration of the optimal stimulation protocol, and investigation of detailed neural mechanisms are clearly needed in future studies.

Is the dynamic gait index a useful outcome to measure balance and ambulation in patients with cerebellar ataxia?

BACKGROUND

Ataxia can adversely affect balance and gait and increase the incidence of falls, which puts individuals at greater risk for injury. Thus, interventions focused on balance and gait are integral in rehabilitation training. In order to determine if rehabilitation interventions are effective, we need an outcome measure to detect change. To our knowledge, no activity level outcome measures have been established for balance and gait in cerebellar ataxia.

OBJECTIVE

The aim of the current study is to determine the reliability and validity of the Dynamic Gait Index (DGI) for ataxia.

DESIGN

Twenty adult participants (23-84 years) with ataxia were evaluated to assess construct validity, inter-rater reliability, and same day test-retest reliability of the DGI.

METHODS

Participants completed ataxia-specific impairment level outcome measures, as well as the DGI. In addition to the in-person rater, three additional physical therapists scored video recordings of DGI test and retests. Construct validity was assessed via Spearman's rank order correlation coefficient (Spearman's rho) between the impairment measures (Scale for Assessment and Rating of Ataxia (SARA), International Cooperative of Ataxia Rating Scale (ICARS) and the DGI. Reliability was assessed by Spearman's rho and Intraclass Correlation Coefficient ICC (2,1).

RESULTS

In terms of construct validity, we found significant correlations between the activity level DGI and impairment level outcome measures (-0.81 for SARA; -0.88 with ICARS). The interrater reliability of the DGI applied to participants with ataxia was high (Spearman rho: range 0.71-0.98; ICC (2,1) 0.98) as was test-retest reliability (Spearman rho: 0.95; ICC (2,1) 0.98).

CONCLUSION

We showed that the DGI is a reliable and valid outcome measure to be used in the clinic for individuals with cerebellar ataxia. The DGI had excellent inter-rater and test-retest reliability for raters with varying years of clinical experience. Therefore, the DGI can be a useful clinical outcome measure for assessing balance and ambulation for individuals with cerebellar ataxia.

Instrumented Objective Clinical Examination of Cerebellar Ataxia: the Upper and Lower Limb-a Review

Cerebellar dysfunction results in impairments in co-ordination or 'ataxia'. Bedside examination of cerebellar function has changed little since the early nineteenth century with the exception being the oculomotor examination which has become instrumented. Otherwise, competence and confidence in performing the clinical assessment relies heavily on the skill and experience of the clinician. Potentially, instrumented objective measurement will more accurately assess the severity of ataxia and the changes brought about by advancing therapies in pharmaceutical trials and in rehabilitation intervention. This study describes instrumented versions of several bedside tests of cerebellar function, including rhythmic tapping of the hand (RTH), finger-nose test (FNT), dysdiadochokinesia (DDK), ramp tracking (RMT), ballistic tracking (BT), rhythmic tapping of the foot (RTF) and the heel shin (HST) examination which were validated against scores from Ataxia Rating Scales (ARS) such as the Scale of Assessment and Rating of Ataxia (SARA). While all of the instrumented tests accurately distinguished between ataxic subjects and controls, there was a difference in performance, with the best four performing upper limb tests being RTH, FNT, DDK and BT. A combination of BT plus RTH provided the best correlation with the SARA and outperformed a combination of all the bedside tests (Spearman 0.8; p < 0.001 compared to 0.68; p < 0.001 for the combined set) in identifying the presence and severity of ataxia. This indicates that there is redundancy in the information provided by the bedside tests and that adding other tests to BT plus RTH does not add accuracy to the assessment of ataxia. This analysis highlighted the need for metrics that could be generalised to each of the assessments of ataxia, so, in turn, domains of stability, timing, accuracy and rhythmicity (STAR domains) were developed and compared to the SARA. The STAR criteria could potentially influence the future of instrumented assessment in CA and pave the way for further research into the objective measurement of the cerebellar examination.

Hand Dexterity and Pyramidal Dysfunction in Friedreich Ataxia, A Finger Tapping Study

Background

Loss of hand dexterity has a profound impact on disability in patients with cerebellar, pyramidal, or extrapyramidal diseases. Analysis of multiple finger tapping (FT) parameters can contribute to identify the underlying physiopathology, while providing a quantitative clinical assessment tool, particularly in patients not reliably evaluated using clinical rating scales. Here, we used an automated method of FT analysis in Friedreich ataxia (FRDA) to disentangle cerebellar (prominent FT rate variability), extrapyramidal (FT progressive amplitude reduction without slowing of tapping rate), and pyramidal (progressive decrease of FT rate and amplitude) contribution to upper limb loss of dexterity. FT parameters were then related to FRDA clinical parameters and upper limbs motor evoked potential (MEPs).

Methods

Twenty-four FRDA patients and matched healthy subjects performed FT with the dominant hand for 90 seconds. FT rate, FT rate variability, FT amplitude, and linear regressions of FT movement parameters were automatically computed. Eleven patients underwent MEPs, measured at the first dorsal interosseous of the dominant hand to determine central motor conduction time (CMCT).

Results

FRDA patients had slower and more regular FT rate than controls. Eleven FRDA patients showed FT rate slowing. Those patients had longer disease duration and higher Scale for the Assessment and Rating of Ataxia (SARA) scores. Seven patients with FT rate slowing had MEP and all displayed prolonged CMCT, whereas the 4 other patients with constant FT rate had normal CMCT.

Conclusion

This study provides evidence for a prominent involvement of pyramidal dysfunction in upper limb dexterity loss as well as a potential outcome measure for clinical studies in FRDA.

Rehabilitation for ataxia study: protocol for a randomised controlled trial of an outpatient and supported home-based physiotherapy programme for people with hereditary cerebellar ataxia

INTRODUCTION

Emerging evidence indicates that rehabilitation can improve ataxia, mobility and independence in everyday activities in individuals with hereditary cerebellar ataxia. However, with the rarity of the genetic ataxias and known recruitment challenges in rehabilitation trials, most studies have been underpowered, non-randomised or non-controlled. This study will be the first, appropriately powered randomised controlled trial to examine the efficacy of an outpatient and home-based rehabilitation programme on improving motor function for individuals with hereditary cerebellar ataxia.

METHODS AND ANALYSIS

This randomised, single-blind, parallel group trial will compare a 30-week rehabilitation programme to standard care in individuals with hereditary cerebellar ataxia. Eighty individuals with a hereditary cerebellar ataxia, aged 15 years and above, will be recruited. The rehabilitation programme will include 6 weeks of outpatient land and aquatic physiotherapy followed immediately by a 24- week home exercise programme supported with fortnightly physiotherapy sessions. Participants in the standard care group will be asked to continue their usual physical activity. The primary outcome will be the motor domain of the Functional Independence Measure. Secondary outcomes will measure the motor impairment related to ataxia, balance, quality of life and cost-effectiveness. Outcomes will be administered at baseline, 7 weeks, 18 weeks and 30 weeks by a physiotherapist blinded to group allocation. A repeated measures mixed-effects linear regression model will be used to analyse the effect of the treatment group for each of the dependent continuous variables. The primary efficacy analysis will follow the intention-to-treat principle.

ETHICS AND DISSEMINATION

The study has been approved by the Monash Health Human Research Ethics Committee (HREC/18/MonH/418) and the Human Research Ethics Committee of the Northern Territory Department of Health and Menzies School of Health Research (2019/3503). Results will be published in peer-reviewed journals, presented at national and/or international conferences and disseminated to Australian ataxia support groups.

TRIAL REGISTRATION NUMBER

ACTRN12618000908235.

Can the ARAT Be Used to Measure Arm Function in People With Cerebellar Ataxia?

OBJECTIVE

For people with ataxia, there are validated outcome measures to address body function and structure (BFS) impairments and participation; however, no outcome measure exists for upper extremity (UE) activity level in this population. The purpose of this study was to determine whether the action research arm test (ARAT), a measure of UE activity validated for other neurological conditions, might be a useful outcome measure for capturing UE activity limitations in ataxia.

METHODS

A total of 22 participants with ataxia were evaluated to assess construct validity of the ARAT; 19 of the participants were included in the interrater reliability assessment. Participants received a neurologic examination and completed a battery of outcome measures, including the ARAT. ARAT performance was video recorded and scored by 4 additional raters.

RESULTS

For construct validity, Spearman rho showed a significant moderate relationship between the ARAT and BSF outcome measures. A small, nonsignificant relationship was noted for the ARAT and the participation measure. For interrater reliability, Spearman rho showed a large, significant relationship among all raters for the ARAT (range = .87-.94). High reliability was demonstrated using the intraclass correlation coefficient ([2,1] = .97).

CONCLUSION

The ARAT is moderately correlated with ataxia BFS outcome measures, but not with participation scores. The ARAT is a measure of UE activity, which is different from BFS and participation outcome measures. The ARAT was identified to have strong interrater reliability among raters with varying amounts of experience administering the ARAT. Thus, for the ataxic population, the ARAT may be useful for assessing UE activity limitations.

IMPACT

Ataxia can negatively affect reaching tasks; therefore, it is important to assess UE activity level in people with ataxia. Until this study, no outcome measure had been identified for this purpose.

LAY SUMMARY

People with ataxia may have difficulty with daily tasks that require reaching. The ARAT is an outcome measure that clinicians can use to assess UE activity limitations to help design a treatment program.

Application of the Scale for the Assessment and Rating of Ataxia (SARA) in pediatric oncology patients: A multicenter study

Posterior cranial fossa (PCF) tumors in childhood are often associated with ataxia as well as other motor, neurobehavioral and linguistic impairment. The use of a reliable outcome measure is mandatory to evaluate the severity of impairment and monitor rehabilitation effectiveness. The aim of this work is to explore the validity of the Scale for the Assessment and Rating of Ataxia (SARA) in pediatric subjects with ataxia secondary to PCF tumor resection and evaluate the influence of age and comorbidities. Seventy eight patients (3-18 years) were recruited in 5 centers from 2016 to 2018. The age effect on SARA was analyzed by correlating total SARA scores and item scores with age and gradually excluding youngest subjects. The comorbidity effect was evaluated by comparing the ataxia-only group vs a group of subjects with ataxia + dysfunction of cranial nerves or cerebellar mutism (CM) and a group of patients with ataxia + hemiparesis. Several negative correlations between SARA scores and age were found under age 9. Differences between ataxia-only group and the other two groups were closely associated with specific comorbidities (e.g. speech disturbance in cranial nerves or CM group (p value < 0.001) and gait, stance, sitting and finger chase in the hemiparetic group (mean p value 0.022)).

Assessment of Ataxia Rating Scales and Cerebellar Functional Tests: Critique and Recommendations

BACKGROUND

We assessed the clinimetric properties of ataxia rating scales and functional tests, and made recommendations regarding their use.

METHODS

A systematic literature search was conducted to identify the instruments used to rate ataxia symptoms. The identified rating scales and functional ability tests were reviewed and ranked by the panel as "recommended," "suggested," or "listed" for the assessment of patients with discrete cerebellar disorders, using previously established criteria.

RESULTS

We reviewed 14 instruments (9 rating scales and 5 functional tests). "Recommended" rating scales for the assessment of symptoms severity were: for Friedreich's ataxia, the Friedreich's Ataxia Rating Scale, the International Cooperative Ataxia Rating Scale (ICARS), and the Scale for the Assessment and Rating of Ataxia (SARA); for spinocerebellar ataxias, ICARS and SARA; for ataxia telangiectasia: ICARS and SARA; for brain tumors, SARA; for congenital disorder of glycosylation-phosphomannomutase-2 deficiency, ICARS; for cerebellar symptoms in multiple sclerosis, ICARS; for cerebellar symptoms in multiple system atrophy: Unified Multiple System Atrophy Rating Scale and ICARS; and for fragile X-associated tremor ataxia syndrome, ICARS. "Recommended" functional tests were: for Friedreich's ataxia, Ataxia Functional Composite Score and Composite Cerebellar Functional Severity Score; and for spinocerebellar ataxias, Ataxia Functional Composite Score, Composite Cerebellar Functional Severity Score, and SCA Functional Index.

CONCLUSIONS

We identified some "recommended" scales and functional tests for the assessment of patients with major hereditary ataxias and other cerebellar disorders. The main limitations of these instruments include the limited assessment of patients in the more severe end of the spectrum and children. Further research in these populations is warranted. © 2020 International Parkinson and Movement Disorder Society.

MR Imaging of SCA3/MJD

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a progressive autosomal dominantly inherited cerebellar ataxia characterized by the aggregation of polyglutamine-expanded protein within neuronal nuclei in the brain, which can lead to brain damage that precedes the onset of clinical manifestations. Magnetic resonance imaging (MRI) techniques such as morphometric MRI, diffusion tensor imaging (DTI), functional magnetic resonance imaging (fMRI), and magnetic resonance spectroscopy (MRS) have gained increasing attention as non-invasive and quantitative methods for the assessment of structural and functional alterations in clinical SCA3/MJD patients as well as preclinical carriers. Morphometric MRI has demonstrated typical patterns of atrophy or volume loss in the cerebellum and brainstem with extensive lesions in some supratentorial areas. DTI has detected widespread microstructural alterations in brain white matter, which indicate disrupted brain anatomical connectivity. Task-related fMRI has presented unusual brain activation patterns within the cerebellum and some extracerebellar tissue, reflecting the decreased functional connectivity of these brain regions in SCA3/MJD subjects. MRS has revealed abnormal neurochemical profiles, such as the levels or ratios of N-acetyl aspartate, choline, and creatine, in both clinical cases and preclinical cases before the alterations in brain anatomical structure. Moreover, a number of studies have reported correlations of MR imaging alterations with clinical and genetic features. The utility of these MR imaging techniques can help to identify preclinical SCA3/MJD carriers, monitor disease progression, evaluate response to therapeutic interventions, and illustrate the pathophysiological mechanisms underlying the occurrence, development, and prognosis of SCA3/MJD.

Natural history and epidemiology of the spinocerebellar ataxias: Insights from the first description to nowadays

Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominant inherited diseases that share the degeneration of the cerebellum and its connections as their main feature. We performed a detailed description of the natural history of the main SCAs, focusing on epidemiology, progression, haplotype analysis and its correlation with founder effect, and perspective of future treatments. References for this review were identified by an in-depth literature search on PubMed and selected on the basis of relevance to the topic and on the authors' judgment. More than 40 SCAs have been described so far. SCA3 is the most common subtype worldwide, followed by SCA2 and 6. To evaluate the natural history and to estimate the progression of the main SCAs, consortiums were created all over the globe. Clinical rating scales have been developed to provide an accurate estimation of cerebellar clinical deficits, evaluating cerebellar and non-cerebellar signs. Natural history studies revealed that SCA1 patients' functional status worsened significantly faster than in other SCA subtypes, followed by SCA3, SCA2, SCA6, and SCA10. Number of CAG repeats, age of onset, and ataxia severity at baseline are strong contributors to the risk of death in most SCAs. Understanding the natural history of SCAs is extremely important. Although these are rare diseases, the impact they have on the affected individual are enormous. The advances in the field of genetics are helping understand neuronal functions and dysfunctions and allowing the study and development of possible therapies.

Action perception recruits the cerebellum and is impaired in patients with spinocerebellar ataxia

Our cerebellum has been proposed to generate prediction signals that may help us plan and execute our motor programmes. However, to what extent our cerebellum is also actively involved in perceiving the action of others remains to be elucidated. Using functional MRI, we show here that observing goal-directed hand actions of others bilaterally recruits lobules VI, VIIb and VIIIa in the cerebellar hemispheres. Moreover, whereas healthy subjects (n = 31) were found to be able to discriminate subtle differences in the kinematics of observed limb movements of others, patients suffering from spinocerebellar ataxia type 6 (SCA6; n = 21) were severely impaired in performing such tasks. Our data suggest that the human cerebellum is actively involved in perceiving the kinematics of the hand actions of others and that SCA6 patients’ deficits include a difficulty in perceiving the actions of other individuals. This finding alerts us to the fact that cerebellar disorders can alter social cognition.

Temporal but not spatial dysmetria relates to disease severity in FA

Friedreich's ataxia (FA) is an inherited disease that causes degeneration of the nervous system. Features of FA include proprioceptive and cerebellar deficits leading to impaired muscle coordination and, consequently, dysmetria in force and time of movement. The aim of this study is to characterize dysmetria and its association to disease severity. Also, we examine the neural mechanisms of dysmetria by quantifying the EMG burst area, duration, and time-to-peak of the agonist muscle. Twenty-seven individuals with FA and 13 healthy controls (HCs) performed the modified Functional Ataxia Rating Scale and goal-directed movements with the ankle. Dysmetria was quantified as position and time error during dorsiflexion. FA individuals exhibited greater time but not position error than HCs. Moreover, time error correlated with disease severity and was related to increased agonist EMG burst. Temporal dysmetria is associated to disease severity, likely due to altered activation of the agonist muscle.NEW & NOTEWORTHY For the first time, we quantified spatial and temporal dysmetria and its relation to disease severity in Friedreich's ataxia (FA). We found that FA individuals exhibit temporal but not spatial dysmetria relative to healthy controls. Temporal dysmetria correlated to disease severity in FA and was predicted from an altered activation of the agonist muscle. Therefore, these results provide novel evidence that FA exhibit temporal but not spatial dysmetria, which is different from previous findings on SCA6.

Developing an objective evaluating system to quantify the degree of upper limb movement impairment in patients with severe Friedreich's ataxia

BACKGROUND

The use of standardized tools and objective measurements is essential to test the effectiveness of new drugs or rehabilitative protocols. Friedreich's ataxia (FRDA) patients with severe disease are often unable to perform the quantitative measurement tests currently used.

AIM

The purpose of our study was to develop an easy-to-use application, for touchscreen devices, able to quantify the degree of upper limb movement impairment in patients with severe Friedreich's ataxia. The APP, which we named "Twelve-Red-Squares App-Coo-Test" (12-RSACT), assesses the upper limb ataxia by measuring the test execution time.

METHODS

All patients were clinically evaluated using the Composite Cerebellar Functional Severity (CCFS) and the Scale for the Assessment and Rating of Ataxia (SARA). We recruited 92 healthy subjects and 36 FRDA patients with a SARA mean value of 28.8.1 ± 8.2. All participants in our study underwent upper limb movement assessment using the new 12-RSACT, the Click Test, and a well-established system, i.e., the Nine-Hole Peg Test (9HPT).

RESULTS

We observed a strong linear correlation between the measurements obtained with the 12-RSACT and those obtained with 9HPT, Click Test, CCFS, and SARA. The 12-RSACT was characterized by excellent internal consistency and intra-rater and test-retest reliability. The minimal detectable change (MDC%) was excellent too. Additionally, the 12-RSACT turned out to be faster and easier to perform compared with the 9HPT.

CONCLUSION

The 12-RSACT is an inexpensive test and is easy to use, which can be administered quickly. Therefore, 12-RSACT is a promising tool to assess the upper limb ataxia in FRDA patients and even those with severe diseases.

Temporal Invariance in SCA6 Is Related to Smaller Cerebellar Lobule VI and Greater Disease Severity

Regulating muscle force and timing are fundamental for accurate motor performance. In spinocerebellar ataxia type 6 (SCA6), there is evidence that individuals have greater force dysmetria but display better temporal accuracy during fast goal directed contractions. Here, we test whether greater temporal accuracy occurs in all individuals with SCA6, and can be explained by lesser temporal variability. Further we examine whether it is linked to disease severity and specific degenerative changes in the cerebellum. Nineteen human participants with SCA6 (13 woman) and 18 healthy controls performed fast goal-directed ankle dorsiflexion contractions aiming at a spatiotemporal target. We quantified the endpoint control of these contractions, gray matter (GM) integrity of the cerebellum, and disease severity using the International Cooperative Ataxia Rating Scale (ICARS). SCA6 individuals exhibited lower temporal endpoint error and variability than the healthy controls (p = 0.008). Statistically, SCA6 clustered into two distinct groups for temporal variability. A group with low temporal variability ranging from 10 to 19% (SCA6a) and a group with temporal variability similar to healthy controls (SCA6b; 19-40%).SCA6a exhibited greater disease severity than SCA6b, as assessed with ICARS (p < 0.001). Lower temporal variability, which was not associated with disease duration (R ² = 0.1, p > 0.2), did correlate with both greater ICARS (R ² = 0.3) and reduced GM volume in cerebellar lobule VI (R ² = 0.35). Other cerebellar lobules did not relate to temporal variability. We provide new evidence that a subset of SCA6 with greater loss of GM in cerebellum lobule VI exhibit temporal invariance and more severe ataxia than other SCA6 individuals.SIGNIFICANCE STATEMENT Variability is an inherent feature of voluntary movement, and traditionally more variability in the targeted output infers impaired performance. For example, cerebellar patients present exacerbated temporal variability during multijoint movements, which is thought to contribute to their motor deficits. In the current work, we show that in a subgroup of spinocerebellar ataxia type 6 individuals, temporal variability is lower than that of healthy controls when performing single-joint fast-goal directed movements. This invariance related to exacerbated atrophy of lobule VI of the cerebellum and exacerbated disease severity. The relation between invariance and disease severity suggests that pathological motor variability can manifest not only as an exacerbation but also as a reduction relative to healthy controls.

Neurofilament light chain is a promising serum biomarker in spinocerebellar ataxia type 3

BACKGROUND

Spinocerebellar ataxia type 3 (SCA3) is the most common subtype of autosomal dominantly inherited spinocerebellar ataxias (SCAs). No validated blood biomarker is available to assess either disease progression or therapeutic response. Neurofilament light chain (NfL) was recently proposed as a serum biomarker for many neurodegenerative disorders. The present study investigated whether NfL was a promising serum biomarker for SCA3.

METHODS

Seventeen SCA3 patients and 9 controls were enrolled in cohort A, and 116 SCA3 individuals (preclinical and patients) and 91 controls were recruited as cohort B. We assessed whether serum NfL correlated with cerebrospinal fluid (CSF) NfL in cohort A and correlations between serum NfL levels and clinical features and brain volumes were determined in cohort B. The single-molecule array method was used to measure serum NfL levels. Disease severity was determined using the scale for the assessment and rating of ataxia (SARA) and the international cooperative ataxia rating scale (ICARS). Cerebellar and brainstem volumes were assessed using MRI neuroimaging measurements.

RESULTS

Serum/CSF NfL levels in cohort A were elevated in SCA3 patients, and serum and CSF NfL exhibited a significant positive correlation (r = 0.9179, p < 0.0001). Levels of serum NfL in cohort B were significantly higher in preclinical SCA3 (15.03 ± 7.49 vs 6.88 ± 2.72 pg/ mL, p < 0.0001) and manifest SCA3 subjects (37.56 ± 13.47 vs 9.07 ± 6.02 pg/ mL, p < 0.0001) compared to those in controls. Serum NfL concentrations increased from early disease stage to the next stage. Levels of serum NfL in ATXN3 mutation carriers were positively associated with SARA (r = 0.5458, p < 0.0001) and ICARS scores (r = 0.5522, p < 0.0001). Significant negative associations with cerebellar volumes (r = - 0.4217, p = 0.0003) and brainstem volumes (r = - 0.4263, p = 0.0003) were observed. All changes remained significant after adjustment for age and CAG repeat.

CONCLUSIONS

Levels of serum NfL were significantly elevated in SCA3 individuals and correlated with disease severity. Serum NfL is a promising serum biomarker of disease onset and progression, and a potential candidate biomarker of treatment response in SCA3.

Psychometric properties of the Friedreich Ataxia Rating Scale

Objective

To investigate the psychometric properties of the Friedreich Ataxia Rating Scale neurologic examination (FARSn) and its subscores, as well as the influence of the modifications resulting in the now widely used modified FARS (mFARS) examination.

Methods

Based on cross-sectional FARS data from the FA–Clinical Outcome Measures cohort, we conducted correlation-based psychometric analyses to investigate the interplay of items and subscores within the FARSn/mFARS constructs.

Results

The results provide support for both the FARSn and the mFARS constructs, as well as individually for their upper limb and lower limb coordination components. The omission of the peripheral nervous system subscore (D) and 2 items of the bulbar subscore (A) in the mFARS strengthens the overall construct compared with the complete FARS.

Conclusions

A correlation-based psychometric analysis of the neurologic FARSn score justifies the overall validity of the scale. In addition, omission of items of limited functional significance as created in the mFARS improves the features of the measures. Such information is crucial to the ongoing application of the mFARS in natural history studies and clinical trials. Additional analyses of longitudinal changes will be necessary to fully ascertain its utility, especially in nonambulant patients.

Carboxyl Terminus of Hsp70-Interacting Protein Is Increased in Serum and Cerebrospinal Fluid of Patients With Spinocerebellar Ataxia Type 3

Background: Spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease (MJD) is the most common type of autosomal dominant ataxia. Like other neurodegenerative diseases, is characterized by the dysfunction of the protein quality control (PQC) system. The carboxyl terminus of the Hsp70-interacting protein (CHIP), an important component of PQC, participates in the clearance of misfolded proteins to maintain cellular homeostasis. While no cure for SCA3 exists, the disease progresses slowly. Thus, the identification of biomarkers that indicate the severity and prognosis of this disease would be valuable.

Methods: In this exploratory case-control study, we quantitatively evaluated the concentrations of CHIP in the sera of 80 patients with SCA3 and 80 age and sex-matched controls, using the enzyme-linked immunosorbent assay (ELISA). CHIP levels in the cerebrospinal fluid (CSF) donated by six patients and six healthy volunteers, who were matched for sex and age were also measured. All the baseline data were collected, and the patients underwent clinical evaluation. The correlations between CHIP levels and several clinical measurements were analyzed.

Results: The serum CHIP level in the SCA3 group was (80.93 ± 28.68) ng/mL, which was significantly higher than those in the control group [(40.37 ± 18.55) ng/mL]. Similar results were observed for the CSF [(164.59 ± 42.99) ng/mL and (37.47 ± 7.85) ng/mL, respectively]. CSF CHIP levels were significantly higher than the serum CHIP levels in the SCA3 group but not in the control group. The Dunn-Bonferroni post-hoc for Kruskal-Wallis test revealed no significant difference between the serum and CSF of the patients and the control group. Multivariate linear regression showed that serum CHIP levels correlated positively with disease severity, as measured by the Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS). Moreover, we found that serum CHIP levels were moderately correlated with age in healthy controls.

Conclusion: The present study determined that CHIP levels increased significantly in the serum and CSF of patients with SCA3 and that serum CHIP levels were corelated with disease severity. Thus, CHIP is a promising biomarker for SCA3.

Moving Towards Therapy in SCA1: Insights from Molecular Mechanisms, Identification of Novel Targets, and Planning for Human Trials

The spinocerebellar ataxias (SCAs) are a group of neurodegenerative disorders inherited in an autosomal dominant fashion. The SCAs result in progressive gait imbalance, incoordination of the limbs, speech changes, and oculomotor dysfunction, among other symptoms. Over the past few decades, significant strides have been made in understanding the pathogenic mechanisms underlying these diseases. Although multiple efforts using a combination of genetics and pharmacology with small molecules have been made towards developing new therapeutics, no FDA approved treatment currently exists. In this review, we focus on SCA1, a common SCA subtype, in which some of the greatest advances have been made in understanding disease biology, and consequently potential therapeutic targets. Understanding of the underlying basic biology and targets of therapy in SCA1 is likely to give insight into treatment strategies in other SCAs. The diversity of the biology in the SCAs, and insight from SCA1 suggests, however, that both shared treatment strategies and specific approaches tailored to treat distinct genetic causes of SCA are likely needed for this group of devastating neurological disorders.

Molecular Targets and Therapeutic Strategies in Spinocerebellar Ataxia Type 7

Spinocerebellar ataxia type 7 (SCA7) is a rare autosomal dominant neurodegenerative disorder characterized by progressive neuronal loss in the cerebellum, brainstem, and retina, leading to cerebellar ataxia and blindness as major symptoms. SCA7 is due to the expansion of a CAG triplet repeat that is translated into a polyglutamine tract in ATXN7. Larger SCA7 expansions are associated with earlier onset of symptoms and more severe and rapid disease progression. Here, we summarize the pathological and genetic aspects of SCA7, compile the current knowledge about ATXN7 functions, and then focus on recent advances in understanding the pathogenesis and in developing biomarkers and therapeutic strategies. ATXN7 is a bona fide subunit of the multiprotein SAGA complex, a transcriptional coactivator harboring chromatin remodeling activities, and plays a role in the differentiation of photoreceptors and Purkinje neurons, two highly vulnerable neuronal cell types in SCA7. Polyglutamine expansion in ATXN7 causes its misfolding and intranuclear accumulation, leading to changes in interactions with native partners and/or partners sequestration in insoluble nuclear inclusions. Studies of cellular and animal models of SCA7 have been crucial to unveil pathomechanistic aspects of the disease, including gene deregulation, mitochondrial and metabolic dysfunctions, cell and non-cell autonomous protein toxicity, loss of neuronal identity, and cell death mechanisms. However, a better understanding of the principal molecular mechanisms by which mutant ATXN7 elicits neurotoxicity, and how interconnected pathogenic cascades lead to neurodegeneration is needed for the development of effective therapies. At present, therapeutic strategies using nucleic acid-based molecules to silence mutant ATXN7 gene expression are under development for SCA7.

Spinocerebellar ataxias: prospects and challenges for therapy development

The spinocerebellar ataxias (SCAs) comprise more than 40 autosomal dominant neurodegenerative disorders that present principally with progressive ataxia. Within the past few years, studies of pathogenic mechanisms in the SCAs have led to the development of promising therapeutic strategies, especially for SCAs caused by polyglutamine-coding CAG repeats. Nucleotide-based gene-silencing approaches that target the first steps in the pathogenic cascade are one promising approach not only for polyglutamine SCAs but also for the many other SCAs caused by toxic mutant proteins or RNA. For these and other emerging therapeutic strategies, well-coordinated preparation is needed for fruitful clinical trials. To accomplish this goal, investigators from the United States and Europe are now collaborating to share data from their respective SCA cohorts. Increased knowledge of the natural history of SCAs, including of the premanifest and early symptomatic stages of disease, will improve the prospects for success in clinical trials of disease-modifying drugs. In addition, investigators are seeking validated clinical outcome measures that demonstrate responsiveness to changes in SCA populations. Findings suggest that MRI and magnetic resonance spectroscopy biomarkers will provide objective biological readouts of disease activity and progression, but more work is needed to establish disease-specific biomarkers that track target engagement in therapeutic trials. Together, these efforts suggest that the development of successful therapies for one or more SCAs is not far away.

State biomarkers for Machado Joseph disease: Validation, feasibility and responsiveness to change

Machado-Joseph disease (SCA3/MJD) is the most common spinocerebellar ataxia worldwide, and particularly so in Southern Brazil. Due to an expanded polyglutamine at ataxin-3, SCA3/MJD presents a relentless course with no current disease modifying treatment. Clinical scales used to measure SCA3/MJD progression present moderate effect sizes, a major drawback for their use as main outcomes in clinical trials, given the rarity and slow progression of the disease. This limitation might be overcome by finding good surrogate markers. We present here a review of studies on peripheral and neurophysiological markers in SCA3/MJD that can be candidates for state biomarkers. Data on markers already studied were summarized, giving emphasis on validation against clinical scale, and responsiveness to change. While some biological fluid compounds and neurophysiological parameters showed poor responsiveness, others seemed to be good candidates. Some potential candidates that are waiting for responsiveness studies were serum levels of neuron specific enolase, vestibulo-ocular reflex and video-oculography. Candidates evaluated by RNA and microRNA expression levels need further studies to improve their measurements. Data on peripheral levels of Beclin-1 and DNAJB1 are promising but still incipient. We conclude that several potential candidates should follow onto validating studies for surrogate state biomarkers of SCA3/MJD.

Population medical genetics: translating science to the community

Rare genetic disorders are currently in the spotlight due to the elevated number of different conditions and significant total number of affected patients. The study of these disorders is extremely helpful for the elucidation of physiological processes related with complex disorders. Isolated populations are instrumental for the study of genetic disorders, considering their homogeneity and high proportion of affected patients in a small geographic area. These favorable conditions lead to the creation of a new discipline, known as “population medical genetics”, which integrates medical genetics, population genetics, epidemiological genetics and community genetics. In order to develop practical activities in this new discipline, the National Institute of Population Medical Genetics (INaGeMP) was created in 2008 in Brazil. INaGeMP has developed several tools and funded numerous research activities. In this review, we highlight three successful projects developed in the first 10 years of INaGeMP activities (2008-2018): a newborn screening pilot study for MPS VI in Northeast Brazil, the study of Machado-Joseph disease in Brazilian families with Azorian ancestry, and the high twinning rate in a small town in southern Brazil. The results of these projects in terms of scientific output and contributions to the affected communities highlight the success and importance of INaGeMP.

The role of robotic gait training and tDCS in Friedrich ataxia rehabilitation: A case report

RATIONALE

Friedrich ataxia (FA) is the most common inherited neurodegenerative cerebellar ataxic syndrome. In patients with FA, physiotherapy is highly recommended to improve motor function outcome. Cerebellar transcranial direct current stimulation (tDCS) has been demonstrated to be effective in improving symptoms by modulating cerebellar excitability. Recently, robotic rehabilitation with Lokomat-Pro has been used to treat motor impairment in ataxic syndromes by "modulating" cortical plasticity and cerebello-motor connectivity.

PATIENT CONCERNS

A 29-year-old Italian male with FA, come to our Institute to undergo intensive rehabilitation training. He presented a moderate-to-severe spastic tetraparesis, brisk deep tendon reflexes, moderate dysarthria, occasional difficulty in speaking, and mild delay in swallowing. He was able to stand for at least 10 seconds in the natural position with constant support, and thus he used a wheelchair.

DIAGNOSIS

Tetraparesis in a young patient with FA.

INTERVENTIONS

The effects of a stand-alone robotic gait training with Lokomat-Pro preceded by cerebellar anodal tDCS (a-tDCS) versus Lokomat-Pro preceded by cathodal-tDCS (c-tDCS) are compared.

OUTCOMES

The coupled approach (i.e., tDCS and Lokomat) demonstrated better improvement in functional motor outcomes on the Scale for the Assessment and Rating of Ataxia (SARA).

LESSONS

Although only a single case is described, we found that the combined neuromodulation-neurorobotic approach could become a promising tool in the rehabilitation of cerebellar ataxias, possibly by shaping cerebello-cerebral plasticity and connectivity.

Targeted ballet program mitigates ataxia and improves balance in females with mild-to-moderate multiple sclerosis

Background

Multiple sclerosis (MS) is a disease of the central nervous system that causes ataxia and deficits in balance. Exercise-based therapies have been identified as integral to the recovery of motor function in MS, but few studies have investigated non-traditional movement interventions. We examined a targeted ballet program (TBP) designed to mitigate ataxia and improve balance in females with mild-to-moderate relapsing-remitting MS.

Methods and findings

Twelve females with mild-to-moderate disability due to MS were assessed for study eligibility for the study. Ten participants met the inclusion criteria. Two were lost to unrelated health complications. Eight participants completed the TBP. The TBP met twice a week for 60 minutes for 16 weeks. Assessments included (a) the International Cooperative Ataxia Rating Scale (ICARS), (b) the Mini-Balance Evaluations Systems Test (Mini-BESTest), (c) smoothness of movement during a five-meter walk, and (d) balance in a step to stand task before and after the TBP. There were no TBP-related adverse events. Single-tailed paired samples t-tests and Wilcoxon tests were conducted. Improvements were observed in ICARS (p = 7.11E-05), Mini-BESTest (p = 0.001), smoothness of movement in the left (p = 0.027) and right (p = 0.028) sides of the body, and balance in a step-to-stand task in the back (p = 0.025) direction. Results yielded 42% and 58% improvements in the mean Mini-BESTest and ICARS scores, respectively.

Conclusions

This study adds to current research by providing support for a TBP intervention targeting ataxia and balance in MS. The TBP was well tolerated, improved balance, and mitigated ataxia. Clinical improvements were larger than those of previous studies on physical rehabilitation in MS with similar outcome measures.

Trial registration

ISRCTN ISRCTN67916624.

Neurorehabilitation therapy in spinocerebellar ataxia type 2: A 24-week, rater-blinded, randomized, controlled trial

BACKGROUND

Neurorehabilitation has become in a widely used approach in spinocerebellar ataxias, but there are scarce powerful clinical studies supporting this notion.

OBJECTIVE

The objective of this study was to assess the efficacy of a 24-week neurorehabilitative treatment in spinocerebellar ataxia type 2 patients.

METHODS

A total of 38 spinocerebellar ataxia type 2 patients were enrolled in a rater-blinded, 1:1 randomized, controlled trial using neurorehabilitation for 24 weeks. The treated group received 6 hours of neurorehabilitation therapy, emphasizing on balance, coordination, and muscle strengthening on weekdays, whereas the control group did not receive this intervention. Primary outcome measure was the Scale for the Assessment and Rating of Ataxia score, whereas secondary outcome measures included the count of Inventory of Non-Ataxia Symptoms and saccadic eye movement variables.

RESULTS

The rehabilitated group had high levels of adherence and retention to the therapy and showed a significant decrease of Scale for the Assessment and Rating of Ataxia score at 24 weeks when compared with the controls, mainly for the gait, stance, sitting, finger chase, and heel-shin test items. Changes in Scale for the Assessment and Rating of Ataxia scores were inversely correlated with the mutation size in the rehabilitated group. The nonataxia symptom count and saccadic measures were unchanged during the study.

CONCLUSIONS

A comprehensive 24-week rehabilitation program significantly improves the motor cerebellar symptoms of spinocerebellar ataxia type 2 patients as assessed by the ataxia rating score likely as result of the partial preservation of motor learning and neural plasticity mechanisms. These findings provide evidence in support of this therapeutic approach as palliative treatment in spinocerebellar ataxia type 2 suggesting its use in combination with other symptomatic or neuroprotective drugs and in prodromal stages. © 2018 International Parkinson and Movement Disorder Society.