Natural History of Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay: a 4-Year Longitudinal Study.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a neurologic disorder with generally well-known clinical manifestations. However, few studies assessed their progression rate using a longitudinal design. This study aimed to document the natural history of ARSACS over a 4-year period in terms of upper and lower limb functions, balance, walking capacity, performance in daily living activities, and disease severity. Forty participants were assessed on three occasions over 4 years. Participant performance was reported in raw data as well as in percentage from reference values to consider the normal aging process. Severe balance and walking capacity impairments were found, with a significant performance decrease over the 4 years. Balance reached a floor score of around 6 points on the Berg Balance Scale for participants aged >40 years, while other participants lost about 1.5 points per year. The mean loss in walking speed was 0.044 m/s per year and the mean decrease in the distance walked in 6 min was 20.8 m per year for the whole cohort. Pinch strength, balance, walking speed, and walking distance decreased over time even when reported in percentage from reference values. Major impairments and rapid progression rates were documented in the present study for upper limb coordination, pinch strength, balance, and walking capacity in the ARSACS population. A progression rate beyond the normal aging process was observed. These results provide fundamental insights regarding the disease prognosis that will help to better inform patients, develop specific rehabilitation programs, and improve trial readiness.

A Real-World Study of Nusinersen Effects in Adults with Spinal Muscular Atrophy Type 2 and 3.

BACKGROUND: Spinal muscular atrophy (SMA) is a progressive genetic disorder characterized by muscle weakness ultimately leading to pulmonary impairments that can be fatal. The recent approval of nusinersen, a disease-modifying therapy, substantially changed the prognosis for patients, particularly in children. However, real-world evidence about its long-term effectiveness in adults remains limited. This study aimed to document longitudinal data on motor function, pulmonary function and patient-reported outcome measures of Canadian adults with SMA type 2 and 3 treated with nusinersen. METHODS: Outcomes from 17 patients were collected at the Institut de réadaptation en déficience physique de Québec during routine clinical visits over 36 months post nusinersen treatment, using the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE), Revised Upper Limb Module (RULM), 6-Minute Walk Test (6MWT), Children's Hospital of Philadelphia Adult Test of Neuromuscular Disorders (CHOP-ATEND), SMA functional rating scale (SMAFRS), pulmonary function testing and subjective changes reported by patients. RESULTS: After 36 months, 9 patients showed motor function improvement. Changes beyond the minimal clinically important difference were seen for four patients on the HFMSE, four patients on the RULM and five patients on the 6MWT. Pulmonary function remained stable for most subjects. Subjective positive changes were reported in 88% of patients and five patients showed improvement in the SMAFRS. CONCLUSION: This real-world study demonstrates the positive effects of nusinersen in adults with SMA types 2 and 3. Although stabilizing the patient's condition is considered therapeutic success, this study shows an improvement in motor function and subjective gains in several patients.

A National Spinal Muscular Atrophy Registry for Real-World Evidence.

BACKGROUND: Spinal muscular atrophy (SMA) is a devastating rare disease that affects individuals regardless of ethnicity, gender, and age. The first-approved disease-modifying therapy for SMA, nusinursen, was approved by Health Canada, as well as by American and European regulatory agencies following positive clinical trial outcomes. The trials were conducted in a narrow pediatric population defined by age, severity, and genotype. Broad approval of therapy necessitates close follow-up of potential rare adverse events and effectiveness in the larger real-world population. METHODS: The Canadian Neuromuscular Disease Registry (CNDR) undertook an iterative multi-stakeholder process to expand the existing SMA dataset to capture items relevant to patient outcomes in a post-marketing environment. The CNDR SMA expanded registry is a longitudinal, prospective, observational study of patients with SMA in Canada designed to evaluate the safety and effectiveness of novel therapies and provide practical information unattainable in trials. RESULTS: The consensus expanded dataset includes items that address therapy effectiveness and safety and is collected in a multicenter, prospective, observational study, including SMA patients regardless of therapeutic status. The expanded dataset is aligned with global datasets to facilitate collaboration. Additionally, consensus dataset development aimed to standardize appropriate outcome measures across the network and broader Canadian community. Prospective outcome studies, data use, and analyses are independent of the funding partner. CONCLUSION: Prospective outcome data collected will provide results on safety and effectiveness in a post-therapy approval era. These data are essential to inform improvements in care and access to therapy for all SMA patients.

Wheelchair mobility, motor performance and participation of adult wheelchair users with ARSACS: a cross-sectional study.

PURPOSE: Although approximately 45% of adults with Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) are permanent wheelchair users, this sub population has been less studied. The purpose of this study was to document wheelchair mobility, motor performance, and participation in a cohort of adult wheelchair users with ARSACS. METHODS: We recruited 36 manual and powered wheelchair users with ARSACS, aged between 34 and 64 years, for this cross-sectional study. Participants completed measures regarding wheelchair mobility (Wheelchair Skills Test Questionnaire [WST-Q-F], Wheelchair Use Confidence Scale [WheelCon-F] and Wheelchair Outcome Measure [WhOM-F]), motor performance (Scale for the Assessment and Rating of Ataxia [SARA], Disease Severity Index for adults with ARSACS [DSI-ARSACS], Upper Extremity Performance Test for the Elderly [TEMPA], Standardised Finger to Nose Test [SFNT], grip strength, pinch strength, Lower Extremity Motor Coordination Test [LEMOCOT], Berg Balance Scale [BBS], Timed Up and Go [TUG] and 10-meter Walk Test [10mWT]), and participation (Barthel Index, LSA-F and LIFE-H). Results were compared between age groups (≤49 years and ≥50 years), types of wheelchair used, and available reference values. Correlations were computed between wheelchair mobility, upper limb function, and participation. RESULTS: Participants presented limitations regarding wheelchair skills, motor performance, and participation in daily activities. Despite preserved upper limb strength, wheelchair skills, upper and lower limb coordination, standing balance, and functional independence were generally more impaired after 50 years of age and among powered wheelchair users. Significant moderate correlations were found between wheelchair skills and self-efficacy, upper limb strength and coordination, and participation in daily and social activities. CONCLUSIONS: This study provided the first data sets describing specific characteristics of manual and powered wheelchair users with ARSACS. It supports a need to offer wheelchair skills training interventions to adults with ARSACS, which could increase their daily and social participation.IMPLICATIONS FOR REHABILITATIONAdult wheelchair users with ARSACS present with limited wheelchair skills, significantly impaired motor performance, and reduced participation that generally decreases with age. This profile may serve as comparative data for clinicians to anticipate disease progression.This study provides the first data on distinguishing characteristics between PWC users and MWC users with ARSACS. The main characteristics of PWC users include more severe functional limitations and motor impairments, as well as limited grip strength that contrasts with the general preservation of this function among other adults with ARSACS.There is a need to offer and evaluate wheelchair skills training interventions in the future for adults with ARSACS. The general preservation of grip and pinch strength observed in this population suggests a potential for improvement. Considering the associations found between wheelchair mobility and participation, such interventions may increase users' daily and social participation.

Scale for Ocular motor Disorders in Ataxia (SODA).

Eye movements are fundamental diagnostic and progression markers of various neurological diseases, including those affecting the cerebellum. Despite the high prevalence of abnormal eye movements in patients with cerebellar disorders, the traditional rating scales do not focus on abnormal eye movements. We formed a consortium of neurologists focusing on cerebellar disorders. The consortium aimed to design and validate a novel Scale for Ocular motor Disorders in Ataxia (SODA). The primary purpose of the scale is to determine the extent of ocular motor deficits due to various phenomenologies. A higher score on the scale would suggest a broader range of eye movement deficits. The scale was designed such that it is easy to implement by non-specialized neurological care providers. The scale was not designed to measure each ocular motor dysfunction's severity objectively. Our validation studies revealed that the scale reliably measured the extent of saccade abnormalities and nystagmus. We found a lack of correlation between the total SODA score and the total International Cooperative Ataxia Rating Scale (ICARS), Scale for Assessment and Rating of Ataxia (SARA), or Brief Ataxia Rating Scale (BARS). One explanation is that conventionally reported scales are not dedicated to eye movement disorders; and when present, the measure of ocular motor function is only one subsection of the ataxia rating scales. It is also possible that the severity of ataxias does not correlate with eye movement abnormalities. Nevertheless, the SODA met the consortium's primary goal: to prepare a simple outcome measure that can identify ocular motor dysfunction in patients with cerebellar ataxia.

A Canadian Adult Spinal Muscular Atrophy Outcome Measures Toolkit: Results of a National Consensus using a Modified Delphi Method.

BACKGROUND: Spinal Muscular Atrophy (SMA) is a rare disease that affects 1 in 11 000 live births. Recent developments in SMA treatments have included new disease-modifying therapies that require high quality data to inform decisions around initiation and continuation of therapy. In Canada, there are no nationally agreed upon outcome measures (OM) used in adult SMA. Standardization of OM is essential to obtain high quality data that is comparable among neuromuscular clinics. OBJECTIVE: To develop a recommended toolkit and timing of OM for assessment of adults with SMA. METHODS: A modified delphi method consisting of 2 virtual voting rounds followed by a virtual conference was utilized with a panel of expert clinicians treating adult SMA across Canada. RESULTS: A consensus-derived toolkit of 8 OM was developed across three domains of function, with an additional 3 optional measures. Optimal assessment frequency is 12 months for most patients regardless of therapeutic access, while patients in their first year of receiving disease-modifying therapy should be assessed more frequently. CONCLUSIONS: The implementation of the consensus-derived OM toolkit will improve monitoring and assessment of adult SMA patients, and enrich the quality of real-world evidence. Regular updates to the toolkit must be considered as new evidence becomes available.

A Moving Residual Limb: Botulinum Toxin to the Rescue.

Movement disorders post-amputation are a rare complication and can manifest as the jumping stump phenomenon, a form of peripheral myoclonus. The pathophysiology remains unknown and there is currently no standardized treatment. We describe the case of a 57-year-old male with unremitting stump myoclonus, starting one month after transtibial amputation, in his residual limb without associated phantom or neurological pain. The consequence of the myoclonus was a reduction in prosthetic wearing time. Failure to respond to oral medication led us to attempt the use of botulinum neurotoxin Type A injections in the involved muscles of the residual limb. Injection trials, over a two-year period, resulted in an improvement of movement disorder, an increased prosthetic wearing time and a higher satisfaction level of the patient. Injection of botulinum toxin type A should be considered as an alternative treatment for stump myoclonus to improve prosthetic wearing time and comfort.

Documenting the psychometric properties of the scale for the assessment and rating of ataxia to advance trial readiness of Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay.

BACKGROUND: The Scale for the Assessment and Rating of Ataxia (SARA) is a commonly used scale measuring the severity of cerebellar ataxia and is a candidate for outcome measurement in foreseeable clinical trials in Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS). Documenting its psychometric properties in this population will accelerate clinical trial readiness. The objectives of this study were to document the content and construct validity, the internal consistency, and to explore the 2-year responsiveness and the 4-year interpretability of the SARA in ARSACS. METHODS: The first phase of the study consisted of an international Delphi survey to document the content validity. The second phase consisted of a methodological study from the secondary analysis of a longitudinal study to document the construct validity in 69 participants. Responsiveness to change and interpretability of the SARA was explored among a sub-sample of participants (n = 32 and n = 16, respectively). RESULTS: The SARA demonstrates adequate content validity with possible influence of pyramidal and/or neuropathic involvement. It demonstrates excellent construct validity (rs = 0.77-0.95) and internal consistency (Cronbach's α = 0.89). The responsiveness to change was not significant, and the interpretation of change score increased by 1.9 ± 2.5 falling below the minimal detectable change threshold of 3.06. CONCLUSIONS: The SARA has shown evidences of adequate content validity and excellent construct validity in ARSACS. Responsiveness to change and interpretability will need to be further documented among a larger sample over a longer period of time.

Expanding the clinical description of autosomal recessive spastic ataxia of Charlevoix-Saguenay.

BACKGROUND AND PURPOSE: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) diagnosis is based on the presence of three main clinical features: 1) ataxia, 2) pyramidal involvement, and 3) axonal neuropathy. This study aimed to explore, among a cohort of adults with ARSACS, the prevalence of other signs and symptoms than those commonly describe in this disease and compare their prevalence between younger (<40 years) and older (≥40 years) participants. METHODS: A clinical interview based on a standardized questionnaire was conducted. It included the following items: memory and concentration problems, hearing impairment, epilepsy, spasms, choreathetosis, neuropathic pain, cramps and fecal incontinence. RESULTS: A total of 43 participants were interviewed, with a mean age of 38.9 years and 51.2% were men. Spasms (55.8%), cramps (53.5%), and concentration problems (39.5%) were the most frequent manifestations. Except for choreathetosis, which was present in only one participant, all other signs and symptoms were present in 9.3% to 29.3% of participants. CONCLUSIONS: People with ARSACS may experience many other clinical manifestations than the most commonly described. This study is a preliminary step toward the development of a comprehensive evidence-based clinical care guideline for this population.