Regionally Distinct White Matter Lesions Do Not Contribute to Regional Gray Matter Atrophy in Patients with Multiple Sclerosis

PURPOSE To determine to what extent T1- and T2-regional lesion volumes (RLVs) contribute to total and/or regional gray matter (GM) atrophy in multiple sclerosis (MS). METHODS We studied 110 (67 relapsing-remitting and 43 secondary-progressive) MS patients. SABRE program was used to parcel the brain into 13 regions per hemisphere. Total and regional GM fractions (GMFs) were determined in each region to correct for intraregional size variability. Partial correlations were used to determine associations (holding the converse constant) between RLVs, GMF, and regional GMFs (P < .001 to avoid Type 1 error). RESULTS Partial correlations between RLVs and regional GMFs (controlling for total GMF) for the total MS group were not significant for any of the 26 regions for T2, whereas they were significant for two of the 26 regions for T1. Partial correlations between RLVs and total GMF (controlling for regional GMF) for the total MS group were significant in 9 of 26 regions for T2 (largest r = right lateral inferior frontal, -.45) and 5 of 26 regions for T1 (largest r = right inferior parietal, -.45). CONCLUSIONS Results suggest a model whereby a distinct generalized disease process accounts for GM atrophy better than regionally distinct Wallerian degeneration.