From motor performance to participation: a quantitative descriptive study in adults with autosomal recessive spastic ataxia of Charlevoix-Saguenay

Background: Autosomal 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. Methods: Cross-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. Results: Twenty-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. Conclusions: Results 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.