Differential white and gray matter damage in highly active multiple sclerosis: A prospective cohort study

Abstract

We analyze the differential brain volume changes in highly active multiple sclerosis (HAMS) vs. non-HAMS patients during the disease onset.

Methods: HAMS was defined as: a) patients with 1 relapse in the previous year and at least 1 T1 gadolinium-enhancing lesion or 9 or more T2 lesions while on therapy with other disease modifying treatment (DMD); or b) patients with 2 or more relapses in the previous year, whether on DMD or not. High-resolution T1 weighted MRI scans were acquired at onset and every 12 months for 2 years. Lesion load and brain volume measurements were determined. At onset, gray matter volume (GMV) and white matter volume (WMV) tissue volumes were calculated using the SIENAX. Longitudinal changes were estimated by using SIENA to calculate the percentage of brain volume loss. Differences between volumes per group at onset and at the end of the follow up were established.

Results: 64 patients, mean age 38.4 years, 35 (57%) women were included. A total of 14 (21%) were classified as HAMS. At onset, HAMS patients showed lower GMV and WMV volume compared with non-HAMS patients (p = 0.003 and p = 0.01, respectively). During the follow up, HAMS patients showed a higher decrease in GM volume compared with non-HAMS patients (-0.61 vs. - 0.77, p < 0.001) independent from new lesion as well as relapse rate activity during follow up.

Conclusion: HAMS increased rates of GMV atrophy over 24 months compared to non-HAMS patients independent from relapse rate and new T2 lesions.

Keywords: Atrophy; Gray matter; HAMS; Highly active multiple sclerosis; Multiple sclerosis; White matter.