In-vivo microstructural white matter changes in early spinocerebellar ataxia 2.

OBJECTIVE White matter (WM) integrity of Spinocerebellar ataxia 2 (SCA2) is poorly understood, more so in the early stages of SCA2. In this study, we evaluated the microstructural integrity of the WM tracts with an emphasis on the nature of in-vivo pathological involvement in early SCA2. MATERIALS AND METHODS We evaluated the MRI images of 26 genetically proven SCA2 patients with disease duration less than 5 years and 24 age- and gender-matched healthy controls using tract-based spatial statistics (TBSS) to identify the WM tract changes and their clinico-genetic correlates (age at onset, duration of disease, ataxia severity, and CAG repeat length) using standard methodology. RESULTS The mean age at onset and duration of disease was 28.7 ± 8.51 years and 3.5 ± 0.69 months, respectively. The mean CAG repeat length was 42.5 ± 4.6 and ataxia score was 16.1 ± 4.9. Altered DTI scalars signifying degeneration was present in bilateral anterior thalamic radiation (ATR), corticospinal tract (CST), inferior fronto-occipital fasciculus (IFOF), superior and inferior longitudinal fasciculus (SLF and ILF), uncinate fasciculus (UF), cingulum, corpus callosum (CC), forceps major, and forceps minor (corrected p<0.05). DTI scalars representing demyelination was seen in the superior cerebellar peduncle (SCP) and cerebellar WM. There was a significant correlation of SARA score with axial diffusivity of the bilateral cingulum, ATR, CST, forceps minor, IFOF, ILF, SLF, and SCP on the right side (corrected p<0.05). CONCLUSION Extensive WM involvement is present in early SCA2. The DTI scalars indicate degeneration and demyelination and may have clinical implications.