Primary-progressive multiple sclerosis (PPMS) is characterized by steady worsening of neurologic functioning, without any distinct relapses
(also called attacks or exacerbations) or periods of remission. A person’s rate of progression may vary over time — with occasional plateaus or temporary improvement — but the progression is continuous.
How does PPMS differ from the other disease courses?
Although there is a lot of variability among people with PPMS, we know that as a group, they differ in several ways from people with relapsing forms of MS:
Relapsing forms of MS (including relapsing-remitting MS, and secondary-progressive and progressive-relapsing MS in those individuals who continue to experience relapses) are defined by inflammatory attacks on myelin. PPMS involves much less inflammation of the type seen in relapsing MS. As a result, people with PPMS tend to have fewer brain lesions (also called plaques) than people with relapsing MS and the lesions tend to contain fewer inflammatory cells. People with PPMS also tend to have more lesions in the spinal cord than in the brain. Together, these differences make PPMS more difficult to diagnose and treat than relapsing forms of MS.
In the relapsing forms, women are affected two to three times as often as men; in PPMS, the numbers of women and men are approximately equal.
The average age of onset is approximately 10 years later in PPMS than in relapsing MS.
People with PPMS tend to experience more problems with walking and more difficulty remaining in the workforce.
In general, people with PPMS may also require more assistance with their everyday activities.