Corpus callosum volumetrics and clinical progression in early multiple sclerosis

Corpus callosum (CC) is commonly affected in multiple sclerosis (MS), with known association between CC atrophy and MS clinical activity. In this study, we assessed the association of callosal atrophy, lesions volume and residual CC volume with the clinical disability of early MS patients.

Thirteen MS subjects (9 female, mean age 36.9 years), studied with magnetic resonance imaging (MRI) were selected. MRI scans were performed at baseline (T0), at 6 (T1), 12 (T2), and 24 months (T3) from baseline. CC was segmented into three sections (genu, body, and splenium); callosal boundaries were outlined and all CC lesions were manually traced. Normal CC and CC lesion volumes were measured using a semiautomatic software.

From January 2014 to December 2016, all selected patients had confluent lesions on MRI at T3 with a significant increase in the size of confluent lesions compared to baseline (p=0.0007). At T1, a significant increase in the size of confluent (p=0.02) and single lesions located in the callosal body (p=0.04) was detected in patients with EDSS ≥1.5. Also, CC residual volume (CCR) rather than the whole CC volume (CCV) significantly correlated (p=0.03) with the clinical progression of MS in the whole cohort.

In early MS patients with higher EDSS at baseline, a significant increase in confluent CC lesions size is evident, particularly in the callosal body. Also, median CCR is significantly associated with MS progression in the whole MS group, regardless of initial EDSS. Given their significant association with disability, we encourage measuring CC body lesions and residual CC size for therapeutic decisions and prognostic planning in early MS.