Multiple sclerosis (MS) is a chronic, immune-mediated disease of the central nervous system (CNS) that is characterized by inflammation, demyelination, and neurodegeneration. It remains the most common non-traumatic cause of neurologic disability in young adults and presents in most patients as relapsing-remitting disease. Relapses, caused by inflammatory demyelination, can result in a significant amount of neurological disability and reduced health-related quality of life, and having frequent early relapses is associated with increased risk of longer-term disability. Clinical recovery from early relapses is incomplete in approximately half of patients with MS. The mechanisms underlying relapse recovery are not completely understood.