Secondary progressive multiple sclerosis (MS) may also be referred to as SPMS. The term describes people with multiple sclerosis (MS) who find that they are gradually worsening over time.

People who have previously had relapsing-remitting MS but are gradually changing in between attacks, are referred to as having secondary progressive multiple sclerosis. They may still have attacks but, in general, the attacks tend to be less definite and less often than earlier in their MS course. It is a common later phase of MS, and many people with relapsing-remitting MS eventually switch to secondary progressive MS.

Switching to secondary progressive from relapsing-remitting multiple sclerosis

The progression that patients with secondary progressive MS experience is not because their MS immune activity increases as compared with an earlier time in their disease. In fact, their MRI scans often do not seem to show much new activity at all. One theory for their progression is that the nerve fibers that were injured earlier in their MS are now disappearing, sometimes years after the initial injury. Thus, the progression is not really because of new immune disease, but an after-effect of injury occurring perhaps years before.