Associations between cervical cord gray matter damage and disability in patients with multiple sclerosis.

OBJECTIVES To assess in vivo the volume and the magnetization transfer magnetic resonance imaging (MRI)-detectable damage of the cervical cord gray matter in patients with relapsing-remitting multiple sclerosis (RRMS) and to evaluate whether such damage correlates with disability. DESIGN Cervical cord conventional and magnetization transfer MRI scans were acquired from 18 patients with RRMS (and no T2-visible cervical cord lesions) and 13 age- and sex-matched healthy controls. After ad hoc image postprocessing, characterized by high intraobserver reproducibility, the average magnetization transfer ratio and volume of the cervical cord gray matter from patients and controls were calculated and compared using a 2-tailed t test with Bonferroni correction. The correlation between MRI metrics and Expanded Disability Status Scale score was assessed using the Spearman rank correlation coefficient. RESULTS Compared with healthy controls, patients with RRMS had a lower cervical cord gray matter average magnetization transfer ratio (P = .009). No cervical cord gray matter atrophy was detected. In patients with RRMS, the gray matter average magnetization transfer ratio was correlated with the degree of disability (r = -0.48, P = .048). CONCLUSIONS Cervical cord gray matter is not spared by MS pathology, and such damage is an additional factor contributing to the disability of these patients.