What is a Multiple Sclerosis Relapse?

The Science Behind Your Relapses and How You May Prevent Them

Tired woman at work
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An MS relapse is either a worsening of symptoms that you already have, or the appearance of new  symptoms. It's caused by an MS lesion on your brain or spinal cord. Relapses are also referred to as "exacerbations, attacks, or flares.

What Causes Relapses?

Relapses are caused by the inflammation that occurs when your immune system attacks the myelin surrounding nerves in your brain or spinal cord. Myelin is the protective coating that covers nerves and helps them conduct signals.

When the myelin is attacked by immune cells, a “lesion” or an area of inflammation and eventual damage (demyelination) occurs, making the nerves less efficient in conducting signals. Your symptoms depend on the location of this lesion. For instance, inflammation in the cerebellum can cause loss of balance and coordination, while inflammation of the optic nerves can cause decreased vision.

How Long Do Relapses Last?

In order to be a true MS relapse, the symptoms have to last at least 24 hours. Relapses usually last several weeks, although they can be as short as a couple of days, or as long as several months.

It's also important to note that a relapse must be separated from a previous relapse by at least a month. This is to distinguish it from symptoms that may be from a previously active lesion (which can change as inflammation subsides, remyelination occurs, and/or scar tissue forms).

What are the Symptoms and Signs of a Relapse?

Some relapses are very obvious, for instance, losing your sight in one eye due to an attack of optic neuritis.

However, other relapses may not be as sudden or dramatic and you may just feel extra “wobbly” or tired. The way to really know if you are having a relapse is to have an MRI with gadolinium (contrast material that is injected during the MRI scan). Gadolinium is drawn to areas of inflammation and “lights up” when a lesion is “active.” In this case, demyelination is currently occurring, and you are having a true relapse, rather than feeling symptoms caused by older lesions.

How Can I Prevent a Relapse?

The most important thing that you can do to prevent relapses is to begin using and adhere to one of the disease-modifying therapies. These are shown to reduce relapses by one-third on average over a two-year period, and data is showing that over a longer term (10 years and longer), the average reduction in relapses is much greater.

How Can I Treat a Relapse?

Many relapse symptoms can be treated with high-dose corticosteroids, usually Solu-Medrol. The decision is made to treat a relapse based on how much disability the symptoms are causing and how much they interfere with daily activities. The steroid treatment usually significantly shortens the duration of the most severe symptoms, allowing a faster return to normal activities. However, some symptoms may take a longer time to go away and may never quite clear up entirely.

What is a Pseudoexacerbation?

A pseudoexacerbation is a temporary increase in symptoms that is brought on by an external factor. Most often they are caused by an increase in core body temperature due to heat from hot weather, exertion, or fever—this is called the Uhthoff phenomenon.

Once the body temperature returns to normal, the symptoms subside.

A Personal Note

MS relapses can be incredibly frustrating and anxiety-provoking for both patients and their loved ones.  The first year after my MS diagnosis, I was constantly wondering if the disappearing-reappearing-disappearing tingling in my feet represented new relapses or not.

I have learned that it's important to react and see the neurologist if my symptoms are interfering with daily activities or causing discomfort—for me, my “tingles” are just a quirky unwelcome visitor, and don't signal an impending relapse. This approach has helped to keep me calm and enjoy life, without giving more power to my MS.

Edited by Dr. Colleen Doherty May 4th, 2016

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