Diagnosis

It is very difficult to diagnose chronic fatigue syndrome. Even experts do not have a clear definition of what chronic fatigue actually is or what mechanisms in the brain or nervous system are responsible for it. The best diagnostic approach is to determine if the patient matches the criteria for CFS and to rule out other possible causes of symptoms.

Criteria for Chronic Fatigue Syndrome

The Centers for Disease Control define CFS as a distinct disorder with specific symptoms and physical signs after eliminating other identifiable causes of these symptoms and signs.

1. Four or more of the following symptoms must have been present for longer than 6 months:

Short-term memory loss or a severe inability to concentrate that affects work, school, or other normal activities
Sore throat
Swollen lymph nodes in the neck or armpits
Muscle pain
Pain in a number of joints without redness or swelling
Intense or changing patterns of headaches
Unrefreshing sleep
After any exertion, weariness that lasts for more than a day

2. The fatigue must be severe as indicated by the following:

Sleep or rest does not relieve it.
The fatigue is not the result of excessive work or exercise.
The fatigue substantially impairs a person's ability to function normally at home, at work, and in social occasions.
Even mild exercise often makes the symptoms, especially fatigue, much worse.

3. The fatigue must be a new, not lifelong, condition with a definite time of onset. Often, the condition first appears as a viral upper respiratory tract infection marked by some combination of fever, headache, muscle aches, sore throat, earache, congestion, runny nose, cough, diarrhea, and fatigue. Typically, the initial illness is no more severe than any cold or flu.

4. The symptoms must persist. In ordinary infections, symptoms go away after a few days, but in CFS, fatigue and other symptoms recur or continue for months to years. Many patients experience symptoms as recurring bouts of flu-like illness, with each attack lasting from hours to weeks.

Note: Other symptoms reported with CFS but not part of the criteria include intolerance to alcohol, irritable bowel syndrome, dry eyes and mouth, impaired circulation in the hands and feet, visual disturbances, and painful menstrual periods in women.