Bimonthly Evolution of Cortical Atrophy in Early Relapsing-Remitting Multiple Sclerosis over 2 Years: A Longitudinal Study

Abstract

We investigated the evolution of cortical atrophy in patients with early relapsing-remitting (RR) multiple sclerosis (MS) and its association with lesion volume (LV) accumulation and disability progression. 136 of 181 RRMS patients who participated in the Avonex-Steroids-Azathioprine study were assessed bimonthly for clinical and MRI outcomes over 2 years. MS patients with disease duration (DD) at baseline of ≤24 months were classified in the early group (DD of 1.2 years, n=37), while patients with DD > 24 months were classified in the late group (DD of 7.1 years, n=99). Mixed effect model analysis was used to investigate the associations. Significant changes in whole brain volume (WBV) (P<0.001), cortical volume (CV) (P<0.001), and in T2-LV (P<0.001) were detected. No significant MRI percent change differences were detected between early and late DD groups over 2 years, except for increased T2-LV accumulation between baseline and year 2 in the early DD group (P<0.01). No significant associations were found between changes in T2-LV and CV over the followup. Change in CV was related to the disability progression over the 2 years, after adjusting for DD (P=0.01). Significant cortical atrophy, independent of T2-LV accumulation, occurs in early RRMS over 2 years, and it is associated with the disability progression.