The Responsiveness of Triaxial Accelerometer Measurement of Gait Ataxia Is Higher than That of the Scale for the Assessment and Rating of Ataxia in the Early Stages of Spinocerebellar Degeneration

We reported previously that the average medial-lateral gait amplitude while walking on a straight path determined using triaxial accelerometers fixed on the middle of the upper back may be a quantitative and concise indicator for the severity of cerebellar ataxia. Considering that gait ataxia is a typical initial symptom in a variety of spinocerebellar degeneration (SCD), we aimed to develop quantitative biomarkers for cerebellar ataxia as metric variables. We used triaxial accelerometers to analyze gait parameters in 14 patients with SCD at 3 points over 3 years (at baseline, 1.5 years and 3 years). Analysis of covariance (ANCOVA) models adjusted for the baseline scores were used to estimate sample sizes. The mean medial-lateral amplitude (ML) gained by a triaxial accelerometer fixed on upper back could detect the each 1.5-year change. In the 14 patients, the mean ML(m) was 0.032 +/- 0.007(SD) at entry, 0.037 +/- 0.008 after 1.5-year follow, and 0.042 +/- 0.020 after 3-year follow. In contrast, SARA gait scores were 2.9, 2.9, and 3.0, respectively. The responsiveness of the quantitative evaluation of gait ataxia by triaxial accelerometers is higher than that of the SARA within a 1.5-year follow-up period. Gait analysis by triaxial accelerometers will be complementary to the evaluation of scales like SARA in the assessment of clinical severity of SCD patients in early stage.