Understanding Your Diagnosis: From PRMS to Modern Terminology

Navigating a Multiple Sclerosis (MS) diagnosis is challenging, especially when the words doctors use seem to change. If you have seen the term Progressive Relapsing MS (PRMS) in your records or online, you may be confused to find it is no longer used by most specialists today. In 2013, international experts updated the way MS is classified to better reflect how the disease actually behaves and to help doctors choose the most effective treatments ^[1][2].

Why the Terminology Changed

In the past, MS was often put into rigid boxes. Progressive Relapsing MS (PRMS) was once used to describe people who had a steady worsening of symptoms from the very beginning but also experienced occasional sudden attacks, known as relapses ^[3].

The 2013 updates, known as the Lublin classification, retired PRMS because researchers realized that “relapsing” and “progressive” are not two different diseases, but rather two different things happening at the same time ^[2][4]. Instead of a separate category, doctors now use “qualifiers” to describe your specific MS at this moment:

• The Underlying Course: Is it Primary Progressive (PPMS) or Secondary Progressive (SPMS)? ^[1]
• Activity: Is there evidence of new inflammation (relapses or new spots on an MRI)? ^[4]
• Progression: Is the level of disability steadily increasing over time, independent of relapses? ^[5]

These qualifiers can change. You might be “active” this year, and “not active” in five years.

Defining the Modern Categories

If you were previously told you had PRMS, your diagnosis will now likely fall into one of two categories, depending on how your MS first started:

• Primary Progressive MS (PPMS): This describes people whose symptoms have gradually worsened from their very first MS symptom ^[3][6]. In large studies, a portion of people with PPMS—often estimated around 25% over a given observation period—may show “activity” (relapses or new MRI lesions) at different points in their disease ^[7].
• Secondary Progressive MS (SPMS): This is diagnosed when a person started with Relapsing-Remitting MS (RRMS)—a phase of clear attacks followed by recovery—but later transitioned into a phase where disability worsens steadily ^[3][8]. If this progression is currently accompanied by relapses or new MRI activity, it is called Active SPMS.

Activity vs. Progression: What They Mean for You

The most important shift in modern terminology is the distinction between activity and progression. These terms describe two different processes:

A person can be “active but not progressing” (having relapses but staying stable in between) or “progressing but not active” (getting worse gradually without any new MRI spots or attacks) ^[12][7]. Understanding which of these you are experiencing helps your care team decide if a specific disease-modifying therapy (DMT) is likely to help ^[11].

Common Misunderstandings

It is a common mistake to think that having a relapse automatically means you have “Relapsing MS” and not “Progressive MS.” In reality, many people with progressive forms of the disease still have inflammatory activity ^[13].

Another misunderstanding is that a single bad day, or even a single slightly worse exam, means you are “progressing.” True progression requires confirmed, sustained worsening over time ^[10]. While the names have changed, the goal remains the same: identifying exactly what is happening in your nervous system to provide the most targeted care possible.