Cervical Spinal Cord Degeneration in Spinocerebellar Ataxia Type 7.

BACKGROUND AND PURPOSE

Spinocerebellar ataxia type 7 is an autosomal dominant neurodegenerative disease caused by a cytosine-adenine-guanine (CAG) repeat expansion. Clinically, spinocerebellar ataxia type 7 is characterized by progressive cerebellar ataxia, pyramidal signs, and macular degeneration. In vivo MR imaging studies have shown extensive gray matter degeneration in the cerebellum and, to a lesser extent, in a range of cortical cerebral areas. The purpose of this study was to evaluate the impact of the disease in the spinal cord and its relationship with the patient's impairment.

MATERIALS AND METHODS

Using a semiautomated procedure applied to MR imaging data, we analyzed spinal cord area and eccentricity in a cohort of 48 patients with spinocerebellar ataxia type 7 and compared them with matched healthy controls. The motor impairment in the patient group was evaluated using the Scale for Assessment and Rating of Ataxia.

RESULTS

Our analysis showed a significantly smaller cord area ( = 9.04, < .001, = 1.31) and greater eccentricity ( = -2.25, =. 02, = 0.32) in the patient group. Similarly, smaller cord area was significantly correlated with a greater Scale for Assessment and Rating of Ataxia score ( = -0.44, = .001). A multiple regression model showed that the spinal cord area was strongly associated with longer CAG repetition expansions (= .002) and greater disease duration (= .020).

CONCLUSIONS

Our findings indicate that cervical spinal cord changes are progressive and clinically relevant features of spinocerebellar ataxia type 7, and future investigation of these measures as candidate biomarkers is warranted.