Multiple sclerosis is a chronic, often disabling disease of the central nervous system.  Symptoms may be mild, such as numbness in the limbs, or severe -- paralysis or loss of vision.  Most people with MS are diagnosed between the ages of 20 and 40, but the unpredictable physical and emotional effects can be lifelong.  The progress, severity, and specific symptoms of MS in any one person cannot yet be predicted, but advances in research and treatment are giving hope to those affected by the disease.