Need to Know: MS and Smoldering Lesions

Tamara Sellman avatar

by Tamara Sellman |

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Editor’s note: “Need to Know” is a series inspired by common forum questions and comments from readers. Have a comment or question about MS? Visit our forum. This week’s question is inspired by two forum topics about silent inflammation from August 2019. Have an experience you want to share? Leave a comment here or at the original forum topics.

I have been in remission for a few years now and — knock on wood — I hope that continues for a long time. Like, forever!

My annual MRI showed no changes in my lesions to indicate new activity. As a result, my neurologist put me on a new maintenance plan. My orders? Maintain good health habits, follow my current therapy protocol, get an MRI every other year, and call if new symptoms appear suddenly and don’t resolve.

I wondered why I needed to get an MRI if I wasn’t exhibiting outward symptoms. However, two MS terms — silent inflammation and smoldering lesions — explain why.

Lesion activity in MS

When we think of inflammation, we think of swelling, redness, warmth, pain — hallmarks of acute inflammation. If you break an ankle or develop an earache, you’re going to have acute inflammation, which is temporary and even beneficial to the healing process.

However, overactive inflammatory responses caused by MS result in lesions (plaques or scarring) on the tissue of the central nervous system. Chronic, MS-related inflammation releases immune cells that mistakenly attack the myelin coating of our nerves. Overactive inflammatory responses interfere with signal conduction between the brain and other areas of the body.

MS inflammation is acute during an active flare. But it can also be chronic during and between flares, resulting in muscle spasms, slow speech, and other neurological dysfunctions that define life with MS.

Silent inflammation

Chronic inflammation is noticeable and can be felt, but silent inflammation can go unnoticed for years. Silent inflammation occurs in the background and is prompted by underlying and emergent conditions of which we are often unaware. Silent inflammation is rarely accompanied by outward symptoms.

Consider undiagnosed sleep apnea, for example, which causes systemwide inflammation. If left untreated, sleep apnea can lead to a multitude of chronic health conditions caused or exacerbated by silent inflammation.

For people with MS, persistent silent inflammation can prompt the immune system to over-respond, damaging brain tissue.

Not all lesions burn bright

When we think of MS lesion activity, we look for evidence of active lesions or previously active lesions that are no longer “flaring.”

However, research suggests an in-between stage of lesion activity. Also known as rim lesions or chronic active lesions, smoldering lesions characterize a more aggressive course of MS. Smoldering lesions present with dark, expanding rims around their light centers.

In one study, smoldering lesions were discovered using a high-powered, 7-tesla MRI. Participants with four or more smoldering lesions were nearly twice as likely to develop progressive MS and manifested motor and cognitive disabilities at a younger age.

Why smolders matter

Scientists suspect that “smolders” are visual evidence of aggressive microglia activity in the brain. Microglia are activated by inflammatory responses and clean up cell fragments, waste, and foreign material, such as viruses. For people with MS, however, microglia might also nibble the edges of otherwise inactive lesions, which can enlarge them and lead to disabling damage.

According to the National Institute of Neurological Disorders and Stroke, smoldering lesions might indicate progressive MS. Using MRIs to identify smolders allows medical professionals to apply more aggressive and targeted therapies to prevent further damage during an active course of MS.

Keep an (MRI) on your lesions

In my opinion, smoldering lesions are reason enough to get regular MRIs (as ordered by your neurologist). Before my diagnosis, I didn’t know that I had silent inflammation. Did you? Who’s to say I won’t miss evidence of silent inflammation during remission?

I might feel better today than I feel during a relapse, but that’s no guarantee that lesions I’ve already collected are shrinking or fading. In fact, they might be smoldering. How else am I to know?

I say better safe than sorry.


Note: Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Multiple Sclerosis News Today or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to multiple sclerosis.


Jeff avatar


This is interesting information; having had many MRI's since 1999. Firmly in the SP phase my Neuro has to be prompted to order an MRI. When I do have one I have to watch them carefully as the last order was only for a neck and not the brain. I stopped the procedure and had them confirm the order; which obviously should have included the brain.

This brings up the issue that, in almost all situations, the Radiologist that reads the MRI are not MS Specialist, and are also probably behind in their work load. Misdiagnosis are common enough already, to expect that this detail will be caught is optimistic at best.

Radiology is a business and the cost of this equipment is not recoverable in the majority of tests. While this is a very interesting theory, in practicality it doesn't offer much to most of us. 7 T MRI's are very expensive and currently there are very few available.

Tamara Sellman avatar

Tamara Sellman

Jeff, thanks for sharing this experience.

A reminder: We should know that if we are concerned or have questions about procedures, it's totally fine for us to speak up and ask for orders to be confirmed or for more explanations etc. As patients, we have a right to be involved in this process and that means being informed and listened to.

It's true that 7Ts are still uncommon and expensive, I would venture only people living in major urban centers can even hope to access them.

FWIW my own MS specialist/neurologist is the only one who reads my films, so it's not always the case that a nonMS specialist may be a problem when it comes to interpreting the images.

Come to think of it... the first films I had, although preliminary, were ordered after my visit to my primary care provider, who nudged me over to the radiology clinic across the street the next day, and quite literally, within 48 hours, I was given a preliminary diagnosis of MS based on those film interpretations by that radiologist, who isn't an MS specialist. He definitely got it right.

But there's a lot of differences in the way clinics, labs, hospitals, entire departments are run when it comes to diagnosing and treating chronic illnesses like MS, so it's probably safe to say that "your mileage may vary."

I find it helpful to request to review the films alongside my neuro, and have them slowly show me what they mean by lesions, disease activity, etc.

If a radiology tech or specialist isn't willing to do this, find a doctor who will. It's your right to know what's going on and to not be kept in the dark.

Thanks again for sharing your experiences!

Ircsi Krouse avatar

Ircsi Krouse

After 37 years of MS my Neurogists tell me my lesions are inactive
I feel worse than ever
What is happening to the numerous old inactive lesions

Tamara Sellman avatar

Tamara Sellman

Hi Ircsi
We can have inactive disease and still feel crummy. The old inactive lesions aren't doing anything, but they did leave behind damage that is mostly irreparable That is one of the not-so-great realities of living with this disease.

My lesions have been inactive since my last relapse 7 years ago but I continue to have symptoms even though I'm considered stable and in remission. Once that damage is done, all we can do is manage our pain and discomfort however best we can.

Best of luck to you, I hope you find some relief for your symptoms!


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