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Primary Progressive MS explained

Primary progressive MS is a rare type of MS, as it affects around 10-15% of people diagnosed with MS1. As its name suggest, from the first (primary) symptom, it is progressive. This is unique, as from the onset, symptoms tend to gradually worsen over time, rather than appear as a relapse. In PPMS, there can be long periods of time when symptoms do not change2.

With PPMS, the scarring of the nerve tissues is more common on the spinal cord and often less inflammation is seen. While symptoms of RRMS typically include fatigue, vision problems and muscle weakness3, PPMS is frequently associated with motor control difficulties4, which means the individual may experience difficulty walking or caring for themselves.

PPMS Progression Table
PPMS graph

In PPMS, symptoms (and disability) worsen from diagnosis without a relapsing phase in the early stages.


What are the symptoms of PPMS?

In PPMS, symptoms can often be subtle, such as problems with walking, usually due to spinal cord damage. The first symptom experienced in nearly 80% of people with PPMS is stiffness or weakness in both legs2. It is often difficult to predict the symptoms; however, a person with PPMS may experience any of the following (although this list is not exhaustive)2:

  • Bladder or bowel problems
  • Muscle weakness
  • Fatigue
  • Balance problems¬†

Who is affected by PPMS?

PPMS affects around 10-15% of people diagnosed with MS, typically those in their 40s and 50s2. Unlike RRMS, equal numbers of men and women have primary progressive MS3.

Do relapses occur in PPMS?

Someone with PPMS can experience occasional relapses. PPMS can be further characterised as either active (with an occasional relapse and/or evidence of new MRI activity) or not active4.



  1. MS Society. Primary Progressive MS. Available at: Accessed April 2020.
  2. MS Trust. Primary Progressive MS. Available at: Accessed March 2020.
  3. MS Trust. RRMS What Are The Symptoms. Available at: Accessed April 2020.
  4. MS Trust. Primary Progressive MS. Available at: Accessed April 2020.

UK | July 2020 | MUL20-C021