Corpus callosal diffusivity predicts motor impairment in relapsing-remitting multiple sclerosis: A TBSS and tractography study

► We detect widespread white matter diffusivity changes in early multiple sclerosis. ► Higher diffusivity in motor pathways correlate with impaired fine motor skills. ► Increased callosal motor fiber radial diffusivity predicts declining hand function. ► Diffusivity predicts motor status better than global or tract-specific lesion volume. ► Diffusion changes in relevant pathways are promising biomarkers for MS progression.