The relationship between total and regional corpus callosum atrophy, cognitive impairment and fatigue in multiple sclerosis patients

OBJECTIVE: The objective of this paper is to investigate the relationship between total and regional corpus callosum (CC) atrophy, neuropsychological test performance and fatigue in multiple sclerosis (MS) patients. METHODS: We conducted a cross-sectional study in 113 MS patients: mean age 48+/-11 years, 75/113 women, 84/113 relapsing-remitting MS, mean disease duration 21+/-9 years, mean Expanded Disability Status Scale (EDSS) score 3.2+/-1.7. All patients underwent brain magnetic resonance imaging, standardised neurological assessment and comprehensive cognitive testing including assessments for fatigue and depression. Total and regional CC atrophy was assessed using the corpus callosum index (CCI). RESULTS: CCI correlated more strongly with T2- and T1-lesion volume and whole brain volume than with disease duration or EDSS score. CCI correlated strongly with the verbal fluency test (VFT), Symbol Digit Modalities Test (SDMT) and Paced Auditory Serial Addition Test (PASAT). Multivariate regression analysis revealed that atrophy of the posterior CC segment was significantly associated with poor outcome in the PASAT, VFT and SDMT. In contrast, atrophy of the anterior CC segment was significantly associated with fatigue severity and poor outcome in the long-term memory test. CONCLUSIONS: Atrophy of the CC is associated with cognitive impairment and fatigue. Regional CCI results indicate that these associations are partially spatially segregated.