Primary Progressive MS

Primary progressive MS (PPMS) is one of several types of MS. In PPMS symptoms come on slowly and steadily worsen over time. There are typically no relapses or remissions. The rate of progression can differ from person to person. Even in the same person, the rate of progression can change.1,2

Diagnosing primary progressive MS

PPMS can present differently in each person, making diagnosis hard. The McDonald Criteria are a set of guidelines that can be used to diagnose MS. There is a specific set of characteristics within it for diagnosing PPMS. The criteria require that a person have at least one year of MS-like symptoms and progression not related to another neurologic condition. They must also have 2 of the following:2-4

  • One or more brain lesions in areas of the brain called the periventricular, cortical, juxtacortical, or infratentorial areas
  • More than one lesion in the spinal cord
  • Proteins found on cerebrospinal fluid (CSF) tests called oligoclonal bands (O-bands)

Types of PPMS

PPMS can be classified as active or not active. Active PPMS is the only type that may have relapses (sudden increases in the severity of symptoms). Also, a person with active PPMS develops new MS lesions on brain scans over time. PPMS can further be classified as being with or without progression. When a person is progressing, their symptoms are getting worse. When a person does not have progression, they have few or no new symptoms. This may be called stable PPMS.

All of these groups of PPMS can happen in the same person. They can also change over time. For example, in the first few years after a person is diagnosed, they may have new lesions that develop on brain scans. During this same period, their symptoms may be slowly getting worse. This would be active PPMS with progression. If over the next few years symptoms do not get worse and brain scans remain the same, PPMS could be called not active and without progression. Several years later, the same person could have worsening symptoms but no new brain scan findings. At this point, their PPMS would be called not active but with progression.1,2

Why do types of PPMS matter?

Each person will have a different experience with PPMS. There is no one pathway experienced by everyone. It is possible for one person to experience many different types of PPMS while another has the same type for a long time.

Even though each person is unique, there are benefits to monitoring PPMS. People with active PPMS or PPMS that is progressing may benefit from starting or changing treatment options. As symptoms continue to progress, physical therapy or other symptom management may become more important. Someone who is not progressing and has PPMS that is inactive may be doing well on their current treatment and not need adjustments. Classifying where a person is at on their PPMS journey can help track progress and identify times when treatment needs to change.1

PPMS versus other forms of MS

PPMS is less common than other forms of MS. Only about 10 percent of people with MS have PPMS. PPMS tends to affect people later in life compared to relapsing forms of MS (relapsing-remitting and secondary-progressive MS). On average, people with PPMS are affected 10 years later than those with relapsing forms of MS. Relapsing forms of MS are more likely to affect women, whereas PPMS affects men and women equally.

PPMS often has less inflammation and brain lesions than in relapsing forms of MS. However, people with PPMS tend to have more lesions in the spine. Despite the decrease in overall inflammation, the progression of PPMS can be severe. PPMS often leads to greater difficulties with work and daily activities than relapsing forms of MS.1,2,5

Treating PPMS

Not all MS drugs are effective in treating PPMS. Research is currently underway to find more treatments for PPMS. An example of a drug that is approved for PPMS is ocrelizumab. If you have PPMS, talk with your doctor about the different treatments available for you.1,2,5

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Written by: Casey Hribar | Last reviewed: May 2021.