White Matter Myelin Content and Motor Function in Radiologically Isolated Syndrome and Multiple Sclerosis

Regional myelin water fraction (MWF) in radiologically isolated syndrome (RIS) white matter were compared to relapsing-remitting (RR) and primary-progressive (PP) multiple sclerosis (MS). Results showed myelin damage in some white matter regions of RIS. Early myelin damage in RIS may be associated with subclinical ambulatory dysfunction. Manual dexterity correlated with myelin content in the cortical spinal tract and corpus callosum in PPMS whereas it correlated with myelin heterogeneity in RRMS. These findings suggest that myelin changes in critical white matter tracts have differing impact in gross and fine motor function in RIS and MS subtypes.