Tract-based spatial statistics analysis of diffusion-tensor imaging data in pediatric- and adult-onset multiple sclerosis

Background: White matter (WM) microstructure may vary significantly in pediatric-onset (PO) and adult-onset (AO) patients with multiple sclerosis (MS), a difference that could be explained by the effects of an inherent plasticity in the affected pediatric brains early in the disease, and a phenomenon that does not occur later in life. This hypothesis would support the observation that disease progression is much slower in POMS compared to AOMS patients. Objectives: To examine WM microstructure in the brain of adults with POMS and AOMS, using tract based spatial statistics (TBSS) analysis of diffusion-ten- sor imaging (DTI). Methods: Adults with relapsing-remitting (RR) POMS, who were diagnosed before age of 18 years (n ¼ 16), were compared with age-matched (AOA, n ¼ 23) and disease duration-matched (AOD, n ¼ 22) RR patients who developed MS after the age of 18 years. Scans were analyzed using the FSL software package (Oxford, UK) and statistics were performed using TBSS to evaluate WM micro- structure between groups based on the mean fractional anisotropy (FA) values obtained from the DTI. Results: Widespread cortical and deep WM area differences characterized by increased FA values were seen in the AOAMS compared with POMS group (P < 0.05, TFCE corrected). Significantly increased FA values of posterior WM areas were detected in the AODMS compared with POMS group (P < 0.05, TFCE corrected). Conclusion: Increased FA values in WM areas of the AOMS compared with the POMS patients suggest that diffuse WM microstructure changes are more attributable to age of onset than a sim- ple function of disease duration and age. Hum Brain Mapp 00:000-000, 2012. V C 2012 Wiley Periodicals, Inc.