Call it a flare-up, call it an exacerbation -- whatever you call it, you can't call it fun. Exacerbations of multiple sclerosis are the periodic, sudden worsening of symptoms that so many people with relapsing-remitting MS experience on a regular basis. You're walking along fine when you notice numbness in your right leg. Or suddenly you have double vision. If those symptoms last at least 24 hours, you're going through an exacerbation.
"Exacerbation is a more rapid evolution of new symptoms or worsening of old symptoms than just the overall progression of the disease by itself," says John Richert, MD, vice president for research and programs with the National Multiple Sclerosis Society. "It comes on over a period of hours or days, as opposed to a slow progression that occurs over months and years."