The name for secondary-progressive multiple sclerosis (SPMS) comes from the fact that it follows after the relapsing-remitting disease course
(RRMS). Of the 85 percent of people who are initially diagnosed with RRMS, most will eventually transition to SPMS, which means that after a period of time in which they experience relapses and remissions, the disease will begin to progress more steadily (although not necessarily more quickly), with or without any relapses
(also called attacks or exacerbations).
How does SPMS differ from the other disease courses?
SPMS occurs in people who initially had a relapsing-remitting disease course. In other words, SPMS occurs as a second phase of the disease for many individuals. Primary-progressive MS (PPMS) is the first — and only — phase of the illness for approximately 10 percent of people with MS.
In SPMS, people may or may not continue to experience relapses caused by inflammation; the disease gradually changes from the inflammatory process seen in RRMS to a more steadily progressive phase characterized by nerve damage or loss. People with PPMS never experience any relapses.
While the disease-modifying therapies may be effective for some people with SPMS who are still experiencing relapses, none of these medications have been shown to be beneficial in PPMS.