Chronic fatigue syndrome, or CFS, is a devastating and complex disorder. People with CFS have overwhelming fatigue and a host of other symptoms that are not improved by bed rest and that can get worse after physical activity or mental exertion. They often function at a substantially lower level of activity than they were capable of before they became ill.
Besides severe fatigue, other symptoms include muscle pain, impaired memory or mental concentration, insomnia, and post-exertion malaise lasting more than 24 hours. In some cases, CFS can persist for years.
Researchers have not yet identified what causes CFS, and there are no tests to diagnose CFS. However, because many illnesses have fatigue as a symptom, doctors need to take care to rule out other conditions, which may be treatable.
While a single cause for CFS may yet be identified, another possibility is that CFS has multiple triggers. Some of the possible causes of CFS might be:
- immune dysfunction
- abnormally low blood pressure that can cause fainting (neurally mediated hypotension)
- nutritional deficiency
- stress that activates the axis where the hypothalamus, pituitary, and adrenal glands interact (the HPA axis)
The primary symptom of CFS is unexplained, severe fatigue lasting at least 6 months that is not improved by bed rest and that can get worse after physical activity or mental exertion. Individuals with CFS experience a fatigue so strong that their activity levels and stamina decline dramatically. However, fatigue is not the only symptom, and for some patients may not be the symptom that bothers them the most.
As stated in the 1994 case definition, the fatigue of CFS is accompanied by at least 4 of 8 characteristic symptoms lasting at least 6 months. These symptoms include:
- post-exertion malaise lasting more than 24 hours
- un-refreshing sleep
- significant impairment of short-term memory or concentration
- muscle pain
- pain in the joints without swelling or redness
- headaches of a new type, pattern, or severity
- tender lymph nodes in the neck or armpit
- a sore throat that is frequent or recurring
The symptoms listed above are the symptoms used to diagnose this illness. However, many CFS patients may experience other symptoms, including irritable bowel, depression or other psychological problems, chills and night sweats, visual disturbances, brain fog, difficulty maintaining upright position, dizziness, balance problems, fainting, and allergies or sensitivities to foods, odors, chemicals, medications, or noise.