Quantitative assessment of the evolution of cerebellar signs in spinocerebellar ataxias

Functional Outcomes Associated With Independence in Walking Among People With Hereditary Ataxias: An Exploratory Cross-sectional Study

OBJECTIVE

This study aimed to identify functional outcomes related to independence in walking among people affected by hereditary ataxias.

METHODS

Sixty participants were selected by convenience in a list provided by an organization of people with ataxia. Sociodemographic and clinical data were collected using a semistructured questionnaire. The Assessment and Rating of Ataxia was used to assess and rate cerebellar ataxia. Changes in body structure and function, limitation in activities, and restriction in participation were evaluated with specific outcome measures. Participants were classified as independent in walking if they were able to walk without walking aids or human assistance and as dependent in walking if they have been using walking aids (sticks, crutches, or walkers) for more than 6 months, using a wheelchair for locomotion most of the day, or both. Multivariate logistic regression analyses were conducted hierarchically and in blocks considering upper limbs function, balance systems, sensory functions, postural control, walking, independence, cognition, and perception as independent variables. The prevalence ratio for walking independence was determined.

RESULTS

The final regression model pointed out that gait capacity assessed by the 6-Minute Walk Test and dexterity assessed by the Box and Blocks test were the main markers related to walking independence in individuals with hereditary ataxias.

CONCLUSION

The distance covered in 6 minutes of walking (walking endurance) and upper extremity dexterity can be used to better assess the progression of cerebellar disease related to walking independence in individuals with hereditary ataxias.

IMPACT

This study supports early detection of individuals who are at risk of loss of walking independence and an optimized rehabilitation plan.

Quantitative evaluation of upper limb ataxia in spinocerebellar ataxias

Objective

To quantitatively evaluate upper limb ataxia using a novel pen‐like sensor device in patients with spinocerebellar ataxia (SCA) and to assess its validity, reliability, and sensitivity to disease progression.

Methods

We designed a cross‐sectional and longitudinal study of patients with SCA and healthy controls. Upper limb ataxia was evaluated using a device that measures the three‐dimensional position every 10 msec. Participants were instructed to move a pen‐like part of the device iteratively between two buttons. We evaluated the time, length, velocity, and variation coefficient of the stroke, and calculated the distortion index using the mean squared error. The following scales were also evaluated: Scale for the Assessment and Rating of Ataxia (SARA), the International Cooperative Ataxia Rating Scale (ICARS), and the nine‐hole pegboard test. Subjects were followed 12 months after the baseline evaluation.

Results

A total of 42 patients with SCA and 33 healthy controls were enrolled and evaluated. For all ataxia indices measured using the device there were significant differences between healthy controls and patients with SCA. Among the ataxia indices, the distortion index showed the strongest correlation with the SARA and ICARS upper limb score (Pearson's r = 0.647 and 0.722, respectively). Test–retest reliability was high for most of the ataxia indices. In the longitudinal analysis, the distortion index showed high standardized response mean and adjusted effect size, regardless of disease severity.

Interpretation

Our study demonstrated that the distortion index is a reliable functional marker that is sensitive to longitudinal change in patients with SCA.

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.

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.

Friedreich and dominant ataxias: quantitative differences in cerebellar dysfunction measurements

BACKGROUND

Sensitive outcome measures for clinical trials on cerebellar ataxias are lacking. Most cerebellar ataxias progress very slowly and quantitative measurements are required to evaluate cerebellar dysfunction.

METHODS

We evaluated two scales for rating cerebellar ataxias: the Composite Cerebellar Functional Severity (CCFS) Scale and Scale for the Assessment and Rating of Ataxia (SARA), in patients with spinocerebellar ataxia (SCA) and controls. We evaluated these scales for different diseases and investigated the factors governing the scores obtained. All patients were recruited prospectively.

RESULTS

There were 383 patients with Friedreich's ataxia (FRDA), 205 patients with SCA and 168 controls. In FRDA, 31% of the variance of cerebellar signs with the CCFS and 41% of that with SARA were explained by disease duration, age at onset and the shorter abnormal repeat in the FXN gene. Increases in CCFS and SARA scores per year were lower for FRDA than for SCA (CCFS index: 0.123±0.123 per year vs 0.163±0.179, P<0.001; SARA index: 1.5±1.2 vs 1.7±1.7, P<0.001), indicating slower cerebellar dysfunction indexes for FRDA than for SCA. Patients with SCA2 had higher CCFS scores than patients with SCA1 and SCA3, but similar SARA scores.

CONCLUSIONS

Cerebellar dysfunction, as measured with the CCFS and SARA scales, was more severe in FRDA than in patients with SCA, but with lower progression indexes, within the limits of these types of indexes. Ceiling effects may occur at late stages, for both scales. The CCFS scale is rater-independent and could be used in a multicentre context, as it is simple, rapid and fully automated.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT02069509.

NESSCA Validation and Responsiveness of Several Rating Scales in Spinocerebellar Ataxia Type 2

Spinocerebellar ataxia type 2 (SCA2), caused by a CAG expansion (CAGexp) at ATXN2, has a complex clinical picture. While validated ataxia scales are available, comprehensive instruments to measure all SCA2 neurological manifestations are required. This study aims to validate the Neurological Examination Score for the assessment of Spinocerebellar Ataxias (NESSCA) to be used in SCA2 and to compare its responsiveness to those obtained with other instruments. NESSCA, SARA, SCAFI, and CCFS scales were applied in symptomatic SCA2 patients. Correlations were done with age at onset, disease duration, CAGexp, and between scales. Responsiveness was estimated by comparing deltas of stable to worse patients after 12 months, according to Patient Global Impression of change, and the area under the curve (AUC) of the Receiver Operating Characteristics curve of scores range. Eighty-eight evaluations (49 patients) were obtained. NESSCA had an even distribution and correlated with disease duration (r = 0.55), SARA (r = 0.63), and CAGexp (rho = 0.32): both explained 44% of NESSCA variance. Deltas (95% CI) after 1 year in stable and worse patients were only significantly different for SARA. NESSCA, SARA, SCAFI, and CCFS AUC were 0.63, 0.81, 0.49, and 0.48, respectively. NESSCA is valid to be used in SCA2. However, the only instrument that presented good responsiveness to change in 1 year was SARA. We suggest that NESSCA can be used as a secondary outcome in future trials in SCA2 due to the burden of neurological disabilities related to disease progression.

Planning Future Clinical Trials for Machado-Joseph Disease

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is an autosomal dominant multiple neurological systems degenerative disorder caused by a CAG repeat expansion at ATXN3 gene. Only a few treatments were evaluated in randomized clinical trials (RCT) in SCA3/MJD patients, with a lack of evidence for both disease-modifying and symptomatic therapies. The present chapter discuss in detail major methodological issues for planning future RCT for SCA3/MJD. There are several potential therapies for SCA3/MJD with encouraging preclinical results. Route of treatment, dosage titration and potential therapy biomarkers might differ among candidate drugs; however, the core study design and protocol will be mostly the same. RCT against placebo group is the best study design to test a disease-modifying therapy; the same cannot be stated for some symptomatic treatments. Main outcomes for future RCT are clinical scales: the Scale for the Assessment and Rating of ataxia (SARA) is currently the instrument of choice to prove efficacy of disease-modifying or symptomatic treatments against ataxia, the most important disease feature. Ataxia quantitative scales or its composite scores can be used as primary outcomes to provide preliminary evidence of efficacy in phase 2 RCT, due to a greater sensitivity to change. Details regarding eligibility criteria, randomization, sample size estimation, duration and type of analysis for both disease modifying and symptomatic treatment trials, were also discussed. Finally, a section anticipates the methodological issues for testing novel drugs when an effective treatment is already available. We conclude emphasizing four points, the first being the need of RCT for a number of different aims in the care of SCA3/MJD. Due to large sample sizes needed to warrant power, RCT for disease-modifying therapies should be multicenter enterprises. There is an urge need for surrogate markers validated for several drug classes. Finally, engagement of at risk or presymptomatic individuals in future trials will enable major advances on treatment research for SCA3/MJD.

Monitoring disease progression in spinocerebellar ataxias: implications for treatment and clinical research

INTRODUCTION

Spinocerebellar ataxias (SCAs) are autosomal dominant diseases characterized by progressive gait and limb incoordination, disequilibrium, dysarthria, and eye movement disturbances. Approximately 40 genetic subtypes of SCAs are known and classified according to the causative disease gene/locus. With the possibility of the specific genetic diagnosis in patients and at-risk family members, several clinical scales and functional tests have been validated and used in ataxic patients with the purposes of measuring the entity of disease progression in natural history studies and the possible slowing of neurological impairment in therapeutic trials. Areas covered: This paper reviews the most widely used clinical scales and quantitative tests that contributed in monitoring disease progression of the most common forms of SCAs. Expert commentary: The currently available and validated clinical scales and quantitative performance scores are adequate to measure disease severity, but may require a considerable number of subjects and a long period of treatment to allow the recognition of beneficial effect of interventional therapies. Advanced MRI techniques are a consistent biomarker and maybe useful to track disease progression from the preclinical to the manifest ataxic phase in association with appropriate clinical or paraclinical investigations.

Clinical and genetic study of hereditary spastic paraplegia in Canada

Objective:

To describe the clinical, genetic, and epidemiologic features of hereditary spastic paraplegia (HSP) in Canada and to determine which clinical, radiologic, and genetic factors determine functional outcomes for patients with HSP.

Methods:

We conducted a multicenter observational study of patients who met clinical criteria for the diagnosis of HSP in the provinces of Alberta, Ontario, and Quebec from 2012 to 2015. Characteristics of the participants were analyzed using descriptive statistics. The main outcome measure for a subset of the cohort (n = 48) was the Spastic Paraplegia Rating Scale. We also used the SPATAX-EUROSPA disability stage (disability score) to assess disability (n = 65).

Results:

A total of 526 patients were identified with HSP across the country, and 150 patients had a confirmed genetic diagnosis. Mutations were identified in 15 different genes; the most common were SPAST (SPG4, 48%), ATL1 (SPG3A, 16%), SPG11 (8%), SPG7 (7%), and KIAA0196 (SPG8, 5%). The diagnosis of SPG4 was associated with older age at symptom onset (p = 0.0017). SPG4 and SPG3A were less associated with learning disabilities compared to other subtypes of HSP, and SPG11 was strongly associated with progressive cognitive deficits (odds ratio 87.75, 95% confidence interval 14.04–548.24, p < 0.0001). SPG3A was associated with better functional outcomes compared to other HSP subtypes (p = 0.04) on multivariate analysis. The strongest predictor of significant disability was abnormal brain MRI (p = 0.014).

Conclusions:

The most important predictors of disability in our HSP cohort were SPG11 mutations and abnormal brain MRI. Accurate molecular characterization of well-phenotyped cohorts and international collaboration are essential to establish the natural history of these rare neurodegenerative disorders.

Standardized Assessment of Hereditary Ataxia Patients in Clinical Studies

BACKGROUND

Hereditary ataxias are a heterogeneous group of degenerative diseases of the cerebellum, brainstem, and spinal cord. They may present with isolated ataxia or with additional symptoms going beyond cerebellar deficits. There are an increasing number of clinical studies with the goal to define the natural history of these disorders, develop biomarkers, and investigate therapeutic interventions. Especially, early and preclinical disease stages are currently of particular interest.

METHODS AND RESULTS

Evidence-based, we review standards for sampling and storage of biomaterials, clinical and neuropsychological assessment, as well as neurophysiology and neuroimaging and recommendations for standardized assessment of ataxia patients in multicenter studies.

CONCLUSIONS

DNA, RNA, serum, and, if possible, cerebrospinal fluid samples should be processed following established standards. Clinical assessment in ataxia studies must include use of a validated clinical ataxia scale. There are several validated clinical ataxia scales available. There are no instruments that were specifically designed for assessing neuropsychological and psychiatric symptoms in ataxia disorders. We provide a list of tests that may prove valuable. Quantitative performance tests have the potential to supplement clinical scales. They provide additional objective and quantitative information. Posturography and quantitative movement analysis-despite valid approaches-require standardization before implemented in multicenter studies. Standardization of neurophysiological tools, as required for multicenter interventional trials, is still lacking. Future multicenter neuroimaging studies in ataxias should implement quality assurance measures as defined by the ADNI or other consortia. MRI protocols should allow morphometric analyses.

Planning future clinical trials in Machado Joseph disease: Lessons from a phase 2 trial

BACKGROUND

In a recent phase 2 clinical trial in spinocerebellar ataxia type 3/Machado Joseph disease (SCA3/MJD), a neurogenetic disorder without specific therapy, benefits of lithium carbonate were found only on secondary efficacy outcomes, all related to ataxic features. In order to help designing future studies, we further analyzed the trial data searching for treatment response modifiers and metric properties of spinocerebellar ataxia (SCA) scales.

METHODS

Efficacy analysis was performed with the Neurological Examination Score for the Assessment of Spinocerebellar Ataxia (NESSCA) and the Scale for the Assessment and Rating of Ataxia (SARA) subscores and with the subgroup of patients with independent gait according to the 8-meter walking-time (8MW). Interactions of clinical/molecular findings with treatment response, minimally important differences (MIDs), and sample size estimations for NESSCA, SARA, Spinocerebellar Ataxia Functional Index (SCAFI) and Composite Cerebellar Functional Score (CCFS) were evaluated.

RESULTS

62 SCA3/MJD patients had been randomly assigned (1:1) for the double-blind, placebo-controlled trial. While cerebellar NESSCA (range: 0-7 points) differed between groups 0.64 points (95% CI 0.23 to 1.05, p<0.001) over the whole 48weeks of study, favoring lithium, no effect was found on non-ataxia subscores. Among patients able to perform the 8MW on baseline, NESSCA (p=0.010) and SCAFI (p=0.015) differed between groups favoring lithium. Finally, estimated sample sizes for the scales were provided.

CONCLUSION

Lithium efficacy on cerebellar NESSCA, and on SCAFI and CCFS in the primary analysis, together with the lack of effect on non-ataxia features suggests that lithium should be tested in phase 3 trials in SCA3/MJD and that ataxia scales should be preferred to multisystem neurological instruments as the primary outcome. The inclusion of early stage patients is advisable in future clinical trials in SCA3/MJD.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT01096082.

Assessment of upper limb function in young Friedreich ataxia patients compared to control subjects using a new three-dimensional kinematic protocol

BACKGROUND

The assessment of Friedreich ataxia effects on upper limb function in clinical follow-up remains a challenging issue. To complete the usual clinical scales, an upper limb kinematic protocol adapted to Friedreich ataxia children and young adults has been developed and applied to both patients and control subjects.

METHODS

Nineteen Friedreich ataxia patients (7-24 years old) and fifteen healthy controls (9-24) were examined twice during three tasks (drawing, pointing, pro-supination) inspired from the "International Cooperative Ataxia Rating Scale". A custom-made and adjustable device allowed standardized positioning of the subject (in a seated position) and task execution. A three-dimensional kinematic analysis of the whole upper limb was performed using an electromagnetic device. The between session reliability and measurement errors of spatiotemporal and angular kinematic parameters were quantified before the analysis of their discriminative ability between healthy subjects and patients.

FINDINGS

Most of the parameters were significantly different between ataxia patients and controls, showing the discriminative ability between these two populations. In particular, the task duration, the drawing and pointing errors were higher for ataxia patients. In most of the cases, the between session reliability was found good to excellent for the spatiotemporal parameters and moderate to excellent for the kinematic parameters.

INTERPRETATION

Kinematic differences have been pointed out between Friedreich ataxia patients and controls, leading to a better understanding of the effect of this pathology on upper limb function. Discriminative ability and reliability of the developed protocol were demonstrated for many parameters, making it a relevant tool for clinical follow-up.

Update on degenerative ataxias

PURPOSE OF REVIEW

Degenerative ataxias are a heterogeneous group of disorders that are clinically characterized by progressive ataxia. They can be subdivided into three major groups: the acquired ataxias, which are due to exogenous or endogenous nongenetic causes, the hereditary ataxias, and the nonhereditary degenerative ataxias. On the basis of a review of the literature published in 2009 and 2010, this review gives an update of the most recent developments in the field of ataxia.

RECENT FINDINGS

Using advanced methods of molecular genetic analysis, novel genes for recessive and dominant ataxias were identified. Recent imaging studies in dominantly inherited spinocerebellar ataxias (SCAs) focussed on the analysis of connectivity in the brain. Novel clinical assessment methods were developed and validated in large patient cohorts. Although a phase 3 trial of idebenone in Friedreich ataxia (FRDA) failed, a smaller phase 2 trial of riluzole in a mixed population of ataxia patients suggested a possible antiataxic action of this compound.

SUMMARY

Recent molecular advances underline the diversity of degenerative ataxias. With the progress in the development of clinical assessment methods for ataxia, the methodological requirements to run large interventional trials are now met.