The Lyndonville Journal:

Definition of an Illness

By David S. Bell MD, FAAP

Published in Lyndonville News, January 1999

Is there anything that could be considered typical chronic fatigue syndrome (CFS)? This illness with its myriad of symptoms and variety of outcomes seems to come in all sizes and shapes. If fatigue is the worst symptom we call it CFS, but if muscle pain is the worst symptom we call it fibromyalgia. Is there really a difference? The difficulty in answering this question relates to the fundamental principles that underlie the illness, not just the superficial symptoms.

And it is an important question. The diagnosis is difficult enough when the symptoms are "typical", what about when they are somewhat unusual? Much is said of the crushing fatigue, constant headaches, and difficulty thinking in CFS. But some patients may not have these symptoms dominate their illness and thus become confused as to diagnosis. Some even state that they do not have "fatigue" as the most severe symptom. How could they have chronic fatigue syndrome when fatigue is minor? Going further, what exactly are the defining characteristics of this strange illness?

Fatigue is certainly among the most important characteristics of CFS, but how do you define fatigue? The term "fatigue" is meaningless when it comes to illness because it is a normal state. It is defined as recovery from exertion, and that is exactly what does not happen in CFS. Whatever is the symptom of fatigue in CFS is not a normal state. It is a very ambiguous term. If someone says they have fatigue I do not know what they mean. The fatigue of anemia is tiredness while climbing the stairs. The fatigue of diabetes is tiredness that goes unrecognized until the sugar is corrected. The fatigue of stress is a frazzled tiredness. The fatigue of CFS is unique and very hard to define. The closest term I can come up with is "asthenia."

And, paradoxically, despite the confusion as to the term fatigue, it is not the most severe symptom in most patients with CFS. This is particularly true in children. But while it may not be the most severe symptom, it usually dominates the pattern of other symptoms.

In 1987, our office did a questionnaire study on 100 patients diagnosed with CFS, asking them to list the three most worrisome symptoms they experienced in the order of decreasing severity. Only 49% of patients listed fatigue as the most severe. Other candidates were headache (13%), cognitive difficulties (7%), muscle pain (7%), sore throat (6%), lymph node pain (5%), abdominal pain (5%), joint pain (3%) and other symptoms (5%). Nearly all patients listed fatigue among the top three symptoms. All patients had activity limitation because of fatigue. Of those persons who do not list fatigue in the list of symptoms it is usually because they forgot about it - not even people with CFS always understand the fatigue.

So how can CFS be defined? Assuming the presence of a characteristic physical exam, and no other illness obvious from blood testing, my list of defining characteristics would be the following:

1. Characteristic symptom pattern (fatigue, headache, joint pain, muscle pain, abdominal pain, cognitive difficulties, sensitivities, sore throat, lymph node pain, etc.)
   
   
2. Activity limitation
   
   
3. Orthostatic intolerance
   
   
4. Chronicity
   
   
5. Symptom fluctuation and the presence of relapses and remissions
   
   

The pattern of symptoms is well known to those familiar with CFS, and I will not go into them here. For me, the most important diagnostic feature of this illness is the activity limitation. The patient with CFS is not able to do a normal amount of activity in a day because of "fatigue", whatever that is. It could be described as weakness, or sleepiness, or rubbery muscles or brain fog, or tiredness, but it limits the degree of overall activities. The other symptoms may be present but are not limiting the activity. For example, it is not the joint pain which prevents the CFS patient from activity, it is the fatigue.

And what is normal activity? In another study our office did with the help of friends in the CFIDS community, we asked healthy persons what they did in a normal day. All persons who considered themselves entirely well had at least 12 hours a day of upright activity. In other words they were "up and around" for half of the day, either work or some other activity. Patients with CFS have a limitation of this activity. Mild cases can only be "up and around" for 10 hours a day. This is a limitation because they used to be up and around from 7AM till 10PM, or 15 hours a day. Severe cases are "up and around" for 1 hour a day and that only with rest periods.

The next most important factor is orthostatic intolerance. This aspect of CFS was unknown to me until meeting with Dr. David Streeten, but now I see it as an essential for the diagnosis. Essentially orthostatic intolerance means that all symptoms are worse on being in the upright position. Walking, standing and even sitting are all upright activities. When lying down, most persons with CFS feel better, despite being bored out of their minds.

The chronicity of the symptoms is an equally important feature. Of the many patients I have seen, only a handful can say that they have a single day in the past year where they felt entirely well. Many persons say they have "good days", but they define a good day not by being well but by being improved over the average days. More severe patients may not even have single hours during the past year where they felt entirely well. The day to day persistence of the "sick" feeling is essential to the diagnosis.

And lastly I would emphasize the symptom severity fluctuation along with the variation of the worst symptom. The activity fluctuation may go from two hours a day in one month to four or five hours in another. But during this time different symptoms take the lead in being the most troublesome. Severe headaches for three weeks, followed by muscle pain for the next three. A month later the sore throat is there every day, and another month later the irritable bowel is acting up. Overall, all the symptoms seem to hang around, but they take turns leading the pack. It is the overall pattern of these symptoms that is important in making the diagnosis, not the most prominent symptom on a given day.

This is the reason the list of symptoms in CFS is different from one researcher to another. If you ask about the symptoms on January 1st, they may seem different than if you ask on July 1st. The pattern is the same, always dominated by the "sick" feeling that is so impossible to describe.

Taken together this combination of characteristics defines the illness we are calling CFS. The symptom pattern alone is insufficient for diagnosis, but combined with a typical physician examination and blood tests, and the pattern of illness persistence over time, the diagnosis becomes clear.

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