PPMS steadily worsens after it first develops. Neurological disability will accumulate over time. How fast or to what degree disability develops varies for each person and can't be predicted. And in PPMS -- unlike some other types of MS -- there are no relapses or remissions.
Types of Multiple Sclerosis
Find out more about the types of multiple sclerosis:
Ten percent to 15% of people with multiple sclerosis are diagnosed with PPMS. It affects men and women equally. PPMS tends to be diagnosed later in life than other types of MS.
Because multiple sclerosis is such a complex and variable disease, diagnosing PPMS can be difficult. The diagnosis is often made several years into the disease. That's when doctors can look back and see that the disease is progressing without flare-ups.
Symptoms of Primary Progressive MS
Primary progressive multiple sclerosis largely affects the nerves of the spinal cord. So, the main symptoms often have to do with:
MS -- regardless of which type you have -- is thought to be an autoimmune disease. The body's defense system attacks the protective insulation around the nerves (called myelin) of the brain and spinal cord. This causes inflammation and nerve damage.
In PPMS, though, there is little inflammation. Instead, nerve damage dominates. Damaged nerves interrupt the transmission of nerve signals. This causes neurological symptoms.
Plaques of scar tissue or lesions may eventually form along the damaged nerves in the brain and spinal cord.