Corticospinal tract involvement in spinocerebellar ataxia type 3: a diffusion tensor imaging study

Purpose The aim of this study was to evaluate the integrity of the corticospinal tracts (CST) in patients with SCA3 and age- and gender-matched healthy control subjects using diffusion tensor imaging (DTI). We also looked at the clinical correlates of such diffusivity abnormalities. Methods We assessed 2 cohorts from different Brazilian centers: cohort 1 (n= 29) scanned in a 1.5 T magnet and cohort 2 (n= 91) scanned in a 3.0 T magnet. We used Pearson's coefficients to assess the correlation of CST DTI parameters and ataxia severity (expressed by SARA scores). Results Two different results were obtained. Cohort 1 showed no significant between-group differences in DTI parameters. Cohort 2 showed significant between-group differences in the FA values in the bilateral precentral gyri (p< 0.001), bilateral superior corona radiata (p< 0.001), bilateral posterior limb of the internal capsule (p< 0.001), bilateral cerebral peduncle (p< 0.001), and bilateral basis pontis (p< 0.001). There was moderate correlation between CST diffusivity parameters and SARA scores in cohort 2 (Pearson correlation coefficient: 0.40-0.59). Conclusion DTI particularly at 3 T is able to uncover and quantify CST damage in SCA3. Moreover, CST microstructural damage may contribute with ataxia severity in the disease.