BackgroundAutosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is a recessive neurological disorder with cerebellar, pyramidal and neuropathic features. Natural history data are urgently needed to increase trial readiness. This study aimed to describe the clinical phenotype including dexterity, coordination, strength, mobility, balance, disease severity, participation, and quality of life observed in adults with ARSACS homozygous for the c.8844delT mutation.MethodsCross-sectional study with comparisons between disease stages and with reference values. Outcome measures included Standardized Finger-to-Nose Test, Grip/pinch strength, LEMOCOT, Six-Minute Walk Test, 10-Meter Walk Test, Berg Balance Scale, Spastic Paraplegia Rating Scale, Scale for the Assessment and Rating of Ataxia, LIFE-H, and SF-12.ResultsTwenty-eight participants were recruited with a mean age of 38.1 years. The majority presented with lower limb coordination and fine dexterity scores below three standard deviations compare to reference values, scored under predicted values for mobility measures and were at increased risk of fall. Participants at an earlier disease stage performed better than the others, but individual variability was observed.ConclusionsResults showed overall impaired motor performances and, even in a genetically homogeneous ARSACS population, an individual variability within disease stages. This study lays the foundation for a longitudinal study using quantified measurements.

Although ARSACS is a slow, progressive disease, results showed that mobility, balance, and lower limb performance significantly decreased over the 2-year period and that selected outcome measures were able to capture this decline beyond measurement errors.

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ObjectiveTo develop a disease-specific severity index for adults with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) (DSI-ARSACS) that considers the 3 components (pyramidal, cerebellar, neuropathic) of the disease, and to document its content validity, internal consistency, and construct validity.MethodsThe Beta DSI-ARSACS (17 items) was developed based on literature review and expert inputs and then administered to 26 participants. Items reduction was based on Cronbach α and desirable criteria. Performance measures were administered to assess the construct validity of the final version of the DSI-ARSACS.ResultsThe final DSI-ARSACS have 8 items that can be easily performed during usual medical follow-up. The mean score was 19.6 ± 8.1 (range 6.0–35.5) and the Cronbach α was 0.912. The DSI-ARSACS score increased with disease stage and age (p ≤ 0.001) and was closely correlated with other measures assessing similar construct (9-Hole Peg Test, 10-Meter Walk Test, Scale for the Assessment and Rating of Ataxia, Berg Balance Scale, Barthel Index) (rs = 0.75–0.95, p < 0.01). A moderate but not significant correlation was found with the 6-Minute Walk test (rs = −0.611, p = 0.108).ConclusionsThe DSI-ARSACS is a valid measure of disease severity for the adult ARSACS population that is able to distinguish between patients with different clinical profiles. Further documentation of metrologic properties is necessary, but these first results are promising.