When you Google types of MS, it looks like they fall cleanly into 4 main categories: relapsing remitting, primary progressive, secondary progressive, and progressive relapsing.
The truth? It’s much more complex, says Robert Shin, MD. He would know. He’s director of UVA Health’s MS and Clinical Neuroimmunology Division. Unlike many neurologists, he focuses solely on multiple sclerosis and diseases like it. That allows him to stay on top of the latest advances in multiple sclerosis — including how we define MS types.
We asked Shin to help us understand the forms of MS and why they matter for your treatment.
How We Talk About Types of MS
MS treatment has changed rapidly over the past 30 years. In the 1990s, there was no treatment. Now we have dozens of effective medicines.
How we talk about the different types of MS has changed just as quickly. Over time, people started using different terms and didn’t always agree on what they meant.
At 2 different points, MS experts came together to recommend a clear set of terms. The FDA also introduced new terms.
Out of all that, we ended up with the 4 main types of MS you see all over the internet. The problem? Most patients don’t fall neatly into 1 of the 4 types, Shin explains.
The MS Terms That Matter for Care
Here’s what it boils down to: most people with MS have both relapsing activity and progressive activity. What do these mean?
Relapses are flare-ups or times when you get new or worse symptoms. There are recovery periods between these. You can think of relapsing activity like stair steps. Sometimes, symptoms stick around after a relapse and become permanent.
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Progressive activity looks more like a steady incline. Symptoms gradually get worse with no break.
2 Causes of Disability in MS
There are 2 ways people’s multiple sclerosis gets worse and causes disability.
The first is called relapse-associated worsening (RAW). It’s when you don’t fully recover from a relapse and a symptom becomes permanent.
The second is progression independent of relapse activity (PIRA). That’s the steady, gradual worsening of symptoms.
PIRA vs RAW & What It Means for You
“The main thing that puts MS patients in walkers and wheelchairs, the main driver of disability, is PIRA,” Shin says.
To date, treatment advances have worked better against RAW.
“I’d argue that for most patients, if you get to me early enough and I get you on an effective regimen, you won’t have any attacks,” Shin explains. “However, that doesn’t mean you’ll be fine. Because what we’re not great at is that second part — preventing PIRA.”
Hope for Better Treatments for PIRA
Currently, there are MS medicines that tackle both RAW and PIRA. “Their effect on relapses is awesome and their effect on progression is modest,” Shin shares.
However, researchers have developed a promising new class of medicines. Called BTK-inhibitors, these appear to work better against PIRA than any treatment before.
These medicines must be approved by the FDA before they’re widely available. In December, the FDA named one of the medicines a breakthrough therapy. That helps speed up review of drugs for serious conditions when research shows they may work much better than current options.
“Our hope is these will be better at preventing progression,” Shin says. “That’s the next chapter.”
