Multiple sclerosis occurs more frequently in temperate zones than in areas near the Equator. People with family members diagnosed with MS are at slightly higher risk for developing the disease. The exact cause of MS is unknown. It appears to be an autoimmune disease, in which the immune system is stimulated to attack myelin in the central nervous system. The source of the initial stimulus has not been clearly identified, but it may be a virus or other factor in the environment.
Symptoms vary greatly from person to person, over time, and in intensity.
The diagnosis is therefore made based on a neurological examination and a history of neurological symptoms occurring at two different points in time. Sometimes additional studies are indicated when neurological exam and MRI are not definitive. At present there are abortive, preventive, and symptomatic therapies for treating multiple sclerosis. For acute exacerbations or flare-up of symptoms, steroids are sometimes prescribed to shorten the duration of the attack, usually as a pulse of intravenous methylprednisolone given once a day for 3 to 5 days with or without tapering doses of oral steroids or as oral steroids alone. Within the past few years three new preventive treatments have been approved to reduce the frequency and severity of MS exacerbations.