This type, formerly called chronic progressive MS, develops within 10 years in about 50% of people who have had relapsing-remitting MS. Some people with secondary progressive MS have relapses, but many do not. Over time, people with this condition experience a gradual and continuous increase in symptoms and disability. Secondary progressive MS affects 140,000 people in the United States-between one-third and one-half of people with MS. Fifteen years after developing secondary progressive MS, 50% of people require canes or other walking aids, and 10% need a wheelchair.
A clinical course of MS which initially is relapsing- remitting and then becomes progressive at a variable rate, possibly with an occasional relapse and minor remission. - MS that begins with a pattern of clear-cut relapses and recovery but becomes steadily progressive over time with continued worsening between occasional acute attacls.