Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant disorder caused by a CAG repeat expansion, characterized by progressive cerebellar ataxia and pyramidal signs. Non-motor and extracerebellar symptoms may occur. MRI-based studies in SCA1 focused in the cerebellum and connections, but there are no data about cord damage in the disease and its clinical relevance. To evaluate in vivo spinal cord damage in SCA1, a group of 31 patients with SCA1 and 31 age- and gender-matched healthy controls underwent MRI on a 3T scanner. We used T1-weighted 3D images to estimate the cervical spinal cord area (CA) and eccentricity (CE) at three C2/C3 levels based on a semi-automatic image segmentation protocol. The scale for assessment and rating of ataxia (SARA) was used to quantify disease severity. The groups were significantly different regarding CA (47.26 ± 7.4 vs. 68.8 ± 5.7 mm2, p < 0.001) and CE values (0.803 ± 0.044 vs. 0.774 ± 0.043, p < 0.05). Furthermore, in the patient group, CA presented significant correlation with SARA scores (R = -0.633, p < 0.001) and CAGn expansion (R = -0.658, p < 0.001). CE was not associated with SARA scores (p = 0.431). In the multiple variable regression, CA was strongly associated with disease duration (coefficient -0.360, p < 0.05) and CAGn expansion (coefficient -1.124, p < 0.001). SCA1 is characterized by cervical cord atrophy and anteroposterior flattening. Morphometric analyses of the spinal cord MRI might be a useful biomarker in the disease.
Keywords: Ataxia; Biomarker; MRI; Polyglutamine disorders; Spinal cord; Spinocerebellar ataxia type 1.