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How Do You Know?
There is continual discussion and confusion about what constitutes a relapse or a remission. I'm going to try to discuss it a little more thoroughly, but everyone needs to know that the definitons are a little vague on purpose. This is because everyone's disease course is different. Some people or some relapses will slide outside the norm.
If you think about it, in RRMS a person is always either in relapse or remission. The difference is the behavior of the symptoms. The official definitions are all based on the patient's symptoms and neuro exam, that is, by their "clinical status." There is no recommendation to define either relapses or remissions by specific laboratory tests or by the appearance of lesions or the lack of lesion enhancement on MRI.
A Relapse (Attack, Exacerbation, or Flare-up) is a sudden appearance of new symptoms OR a definite worsening of old symptoms. It may be a combination of new symptoms and worsening old symptoms. These symptoms come on typically over hours to several days. They occasionally appear quite suddenly and may look like a stroke. They may or may not be accompanied by new signs on physical exam indicating a new area of damage in the brain/spinal cord. A relapse "can" include something that is found on physical exam that was not noticed by the patient, like a problems with eye movements, or a newly positive Babinski sign, or reflexes that become pathologically brisk.
A new or worsened symptom must last at least 24 hours. This is where a lot of people become confused. Again there is no hard and fast rule here. A symptom doesn't have to be continuously present (every minute of the day) but it should be noticed in the same spot several times in that 24 hours. This is especially true of "paroxysmal" symptoms, like the jabs of pain in trigeminal neuralgia or a strong jerk of a limb (called a myoclonic jerk), but can include things like the appearance of a new paresthesia. Symptoms (usually paresthesias or pain) that move around and change in location from moment to moment or which are different every day are not characteristic of MS. They are more characteristic of a systemic or metabolic problem with all of the nerves. Remember that, in MS, the symptoms are a result of specific areas of actual damage to the nerve fibers in specific locations. Thus, you would expect to feel the effects of this damage in the "same" spot on the body over and over or constantly, until the nerve heals or "remyelinates."
How Long do Relapses Last?
A relapse may last a very short time. By definition this may be a short as a day. If it is that short, it becomes difficult to be sure unless the symptom is completely new and fairly severe. A relapse may last several days, weeks or even months. In my reading I have seen references to relapses lasting as long as 6 months. Is that the longest? It probably is not. In cases where the relapse continues without improvement for several months, the interpretation what that means would be up to the patient's neurologist.
People with an early and very mild course may be entirely without symptoms at all most of the time. If they become overheated or extremely fatigued they will notice the appearance of symptoms they have had before. If these symptoms last less than a day, then the sources that I have read would refer to this apearance of symptoms as a "pseudo-exacerbation" or a false relapse. For people with more constant symptoms, they may also notice marked variations of the intensity of symptoms or re-appearance of old symptoms with over-heating and overexertion/fatigue. These episodes are typically brief and resolve with cooling off or resting. These would also be considered to be pseudo-exacerbations.
A relapse must follow a period of symptom stability of at least a month. This period of stability is called a "remission." If less time has passed since the last "relapse" then the neurologist may consider it part of the earlier relapse which is evolving over an unusually long time.
The relapse cannot immediately follow a course of steroids. This is because some people will improve during steroids only to have their symptoms "rebound" after stopping the steroids.
What Causes Relapses?
Relapses can definitely appear out of nowhere. But, certain things will predictably cause them. The most common and important of these is infection. Even minor infections like colds, skin infections and urinary infections can bring on a relapse. The reason for this is that MS is clearly an immune-mediated disease. It may even be frankly classifiable as an autoimmune disease, except that the specific antibody or immune reaction has not been found. Any process that stimulates the immune system is likely to cause a relapse. All infections "ramp up" the immune system and are potent stimulators. At the first recognition of a relapse it is important to check for signs of infection and test for common ones like UTIs, urinary tract infections. However, there are other factors that have been recognized as relapse triggers. One of these is vaccinations. In general, the relapses seen with immunizations are far less in severity than those seen with the diseases for which they are given. Another, though still debated, is severe psychosocial stress. Interestingly enough, physical trauma has not been shown to trigger relapses.
A woman in the first 3 months after childbirth is quite likely to suffer a relapse. During pregnancy a woman typically has the fewest symptoms than at any other time during the course of the disease. During this time her immune system is suppressed somewhat to protect from rejection of the fetus. Half of the fetus' tissue types are different from the mother's. After delivery the mother's immune system ramps back to full force and major relapses often occur. This is the most widely held explanation for post-partum relapses.
A remission is a period of at least 30 days during which a person is symptom-free or during which the intensity of the symptoms that they do have is stable. They will not be acquiring new symptoms. The little variations of symptoms that are present (due to heat or fatigue, etc) are discussed above. The 30 days to define a remission cannot count begin immediately following a course of steroids. The reason for this is that the steroids will calm the active inflammation of new lesions and may also calm the intensity of a person's symptoms. The description is vague, because the length of time steroids may calm the inflammation of active demyelination can vary from person to person and from attack to attack. This situation would need to be individually interpreted by the neurologist.
How Long Can Remissions Last?
The literature is quite clear that a person may present with MS and have the first, or maybe a few relapses, then go into remission that lasts a decade or more. These people are often said to being having a benign course. However, studies are showing that even without overt symptoms many fo these people do suffer both loss of brain volume and measurable cognitive deficits.
There are no rules about how long remissions can be expected to last, especially as more and more people use the Disease Modifying Drugs that are available.
Note: The Use of steroids makes defining both a relapse and a remission somewhat difficult. A person's symptoms may quiet for some time after steroids or their symptoms may rebound with renewed strength after stopping them. Each person is different.
All people have a baseline of symptoms that vary individually. People having a milder course with their MS may be lucky enough to feel completely well between rare relapses. Many others will have some level of ongoing symptoms that are always present whether they are in remission or in a relapse with additional symptoms. Sometimes these ongoing symptoms will be quiet (less severe) for a while, and then there will be days or weeks when they are worse. This could be due to fatigue or heat exposure or other things in the person's environment. These variations are a part of a person's baseline. Whether the worse periods are called true relapses is up to the interpretation of the doctor based on the experience of the patient. It makes most sense to me to think of these as "normal variations" of a person's disease. It is much like the variations a healthy person will note in their daily energy. They may have more energy at some times in the day and less at others. Also, there may be days in a row, where energy is low or extremely high. Over time, the particular MS symptoms that a person deals with, on an ongoing basis, will change as some lesions in the CNS heal and others appear. Thus, a person's "baseline" will change and evolve over time. This is a gray area that seems to be very individual.
If a person has a lot of ups and downs during their remissions, they may very well have similar ups and downs during relapses. Only with multiple relapses and maybe some years, does a person's baseline become clear to them and to their doctors.
WHEN DO YOU CALL YOUR DOCTOR ABOUT A POSSIBLE RELAPSE?
This is a question every person needs to ask their neurologist. Each treating doctor may have specific preferences. If someone is having a lingering new or worsening symptom, or a very severe symptom, most doctors agree that they want to hear about it. After all, the doctor cannot deal with something he/she doesn't know about, but unneeded information can always be ignored. You should ask your doctor how best to reach them with information. The possibilities are 1) phone call with message or request for callback, 2) letter carefully describing the problem which is faxed to the doctor, 3) email the doctor, and 4) try to make an urgent appointment. If in doubt, TELL YOUR DOCTOR. If the symptoms is very severe, first attempt to reach your doctor, but do not hesitate to present to the ER if needed.
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