Context

Multiple sclerosis (MS) is a chronic, immune-mediated disorder of the central nervous system, and one of the most common causes of disability in young people, with an annual incidence ranging from 2 to 10 cases/100 000 persons/year. The disease is classified as either relapsing-remitting MS (RRMS) or primary progressive MS (PPMS) based on the initial disease course.1 People with RRMS have recurrent episodes of neurological deficit (relapses) followed by periods of remission and over time an accumulation of residual deficits and a slow progression of fixed disability supervene in about 80% of them (secondary progressive MS). Approximately, 15% of people with PPMS have a slowly progressive course from onset. PPMS presents at an older age (mean age at onset 40 years) than does RRMS. Preventing progressive disability is the key therapeutic goal for MS. Several pathological processes occur in MS, including engagement of the immune system, T cell-mediated and B cell-mediated mechanisms, demyelination, inflammatory injury of axons and glia, postinflammatory gliosis and neurodegeneration. Several disease-modifying drugs (DMDs) are available for RRMS; however, their relative benefit in delaying disability worsening remains unclear due to the limited …