Chronic fatigue syndrome, or CFS, is a devastating and complex disorder characterized by overwhelming fatigue that is not improved by bed rest and that may be worsened by physical or mental activity. People with CFS most often function at a significantly lower level of activity than they were capable of before the onset of illness.
In addition to these key defining characteristics, patients report various nonspecific symptoms, including weakness, muscle pain, impaired memory and/or mental concentration, insomnia, and post-exertional fatigue lasting more than 24 hours. In some cases, CFS can persist for years.
The cause or causes of CFS have not been identified and no specific diagnostic tests are available. Moreover, since many illnesses have incapacitating fatigue as a symptom, care must be taken to exclude other known and often treatable conditions before a diagnosis of CFS is made.
Case Definition
As of today, the cause or causes of CFS have not been identified and no specific diagnostic tests are available. Therefore, in order to be diagnosed with chronic fatigue syndrome, a patient must satisfy two criteria:
- Have severe chronic fatigue for at least 6 months or longer that is not relieved by rest and not due to medical or psychiatric conditions associated with fatigue as excluded by clinical diagnosis; and
- Concurrently have four or more of the following symptoms:
- self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities
- sore throat that's frequent or recurring
- tender cervical or axillary lymph nodes
- muscle pain
- multi-joint pain without swelling or redness
- headaches of a new type, pattern, or severity
- unrefreshing sleep and
- post-exertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity) lasting more than 24 hours.
Causes of CFS
The cause or causes of CFS remain unknown, despite a vigorous search. While a single cause for CFS may yet be identified, another possibility is that CFS represents a common endpoint of disease resulting from multiple sudden causes. Some of the possible causes of CFS might be due to infectious agents, immunological dysfunction, stress activating the -pituitary adrenal (HPA) axis, neurally mediated hypotension, and/or nutritional deficiency.
Symptoms of CFS
The primary symptoms of CFS are severe fatigue, weakening that is not improved by bed rest and may be worsened with physical or mental activity. It is an all-encompassing fatigue that results in dramatic decline in both activity level and stamina.
The fatigue of CFS is accompanied by characteristic symptoms lasting at least 6 months. These symptoms include:
The fatigue of CFS is accompanied by characteristic symptoms lasting at least 6 months. These symptoms include:
- self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities
- sore throat that's frequent or recurring
- tender cervical (neck) or axillary (armpit) lymph nodes
- muscle pain
- multi-joint pain without swelling or redness
- headaches of a new type, pattern, or severity
- unrefreshing sleep and
- post-exertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity) lasting more than 24 hours.
