The MS Disease Course and How It's Changing

The Way We're Talking About MS Is Changing...

For decades, MS was grouped into familiar categories: relapsing-remitting MS (RRMS), primary progressive MS (PPMS), secondary progressive MS (SPMS), and sometimes clinically isolated syndrome (CIS). These labels helped clinicians describe the overall type of MS someone had and were important for diagnosis, treatment decisions, insurance, and long-term tracking.

But over the years, people living with MS have shared something important:

• “My MRI is stable, but I feel like I’m getting worse.”
• “What I experience day-to-day doesn’t match the MS type I was told I have.”
• “I’m not having relapses, but things are gradually changing.”

Clinicians and researchers have heard you.

Across MS centers, academic research, and community programs, the field is shifting toward a more dynamic, real-time way of describing MS—one that blends the biology of inflammation and progression with your lived experience. The shift better recognizes that MS is not a static condition. Your disease course can—and often does—change over time.

A Note on Terminology: What's Staying, What's Evolving

The traditional categories (RRMS, PPMS, SPMS, CIS) are no longer viewed as the best way to understand what MS is doing right now.

Here’s what’s happening across the MS community:

1. Longstanding labels (RRMS, PPMS, SPMS, CIS) still exist—for now.
   These categories remain part of diagnosis and medical records. Many MS providers, insurers, and educational resources still use them. Adoption of new terminology across the entire MS ecosystem takes time.
2. BUT the field is clearly moving toward describing MS by its current behavior rather than its category.
   This reflects the newest understanding of MS biology and aligns much more closely with what people actually experience day-to-day.
   
3. Expect a long transition period.
   Different providers will adopt this approach at different speeds. Some already use this model routinely; others may take longer to fully shift their language and practice.

A More Accurate, Personalized Description of MS: Activity, Worsening, and Progression

Instead of relying only on the old labels, experts now ask two key questions to understand your MS in real time:

1. Is your MS active?
   Are there new MRI lesions?
   Have you had a relapse or new symptoms?
2. Are your symptoms worsening?
   Did you not fully recover from your recent relapse?
   Are your worsening symptoms temporary or situational?
3. Is your MS progressing?
   Are there gradual changes in walking, balance, fatigue, or thinking—even without a relapse or new lesions?

These three dimensions—activity, worsening, and progression—combine to paint a much fuller and more accurate picture of how MS is affecting you right now, not just what your MRI shows or which category you were assigned years ago.

A Simple Way to Visualize This New Approach

Why This New Model Matters

1. It validates your experience.
   Your MRI may say “stable,” while your body says “something is changing.” This model recognizes both components as real and important.
2. It improves communication and shared decision-making.
   This leads to clearer conversations with your provider and more personalized treatment plans.
3. It guides better treatment decisions.
   Knowing whether your MS is active or progressing helps you and your team decide:
   · Whether to stay on, switch, or step down from medications
   · When to be more proactive with rehabilitation, exercise, or symptom management
   · How to address cognitive or mood changes early
4. It focuses on you—your function, your symptoms, your goals.
   This modern model connects your daily lived experience with clinical tools, helping you stay active, engaged, and empowered.

What This Means Moving Forward

The MS field is in a period of transformation. You may hear both old and new terminology for years to come. What’s most important is:

• You understand the new framework
• You can use it to describe what you’re experiencing
• You feel confident discussing it with your MS care team

Our goal in this series is to discuss the different MS disease courses and to help you bridge the gap between older categories and this more personalized, evolving view of MS.

Read the Full Disease Course Series

• Article 2: Understanding Relapsing MS
• Article 3: Understanding Progressive MS
• Article 4: Putting It All Together