Multiple sclerosis: pathogenesis and treatment.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune demyelinating disease of the central nervous system. It affects approximately 400,000 people in the United States and onset is usually during young adulthood. There are four clinical forms of MS, of which relapsing remitting type is the most common. As the etiology of MS is unknown, finding a cure will remain challenging. The main mechanism of injury appears to be inflammation and 8 agents are now FDA approved to help control MS. These agents for relapsing forms of MS target different parts of the immune system, with the end goal of decreasing and avoiding further inflammation. No agents are FDA approved for the primary progressive version of MS. FDA approved agents include four preparations of interferon β (Avonex, Rebif, Betaseron and Extavia), glatiramer acetate (Copaxone), mitoxantrone (Novantrone), natalizumab (Tysabri) and fingolimod (Gilenya). There are several drug undergoing phase II and III trials. The heterogeneity of the MS disease process, individual patient response, and medication toxicities continue to challenge the treating physician.