Multiple sclerosis types in the United States 2015

Relapsing-remitting MS (RRMS) is characterized by clearly defined relapses of increased disease activity and worsening symptoms. These are followed by remissions in which the disease doesn’t progress. Symptoms may improve or disappear during remission. Approximately 85 percent of patients are diagnosed with RRMS at onset.
Untreated, about 50 percent of people with RRMS transition to secondary-progressive (SPMS) within a decade of the initial diagnosis.
Primary-progressive MS (PPMS) is diagnosed in about 10 percent of MS patients at onset. People with PPMS experience a steady progression of the disease with no clear relapses or remissions. The rate of PPMS is equally divided between men and women. Symptoms usually begin between the ages of 35 and 39.
Progressive-relapsing MS (PRMS) is the rarest form of MS, representing about 5 percent of MS patients. People with PRMS have clear relapses combined with a steady progression of the disease.