Chronic Fatigue Syndrome (CFS)
Chronic fatigue syndrome, or CFS, is a debilitating and complex disorder characterized by profound fatigue that is not improved by bed rest and that may be worsened by physical or mental activity. Persons with CFS most often function at a substantially 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.
Definition of CFS
A great deal of debate has surrounded the issue of how best to define CFS. In an effort to resolve these issues, an international panel of CFS research experts convened in 1994 to draft a definition of CFS that would be useful both to researchers studying the illness and to clinicians diagnosing it. In essence, in order to receive a diagnosis of chronic fatigue syndrome, a patient must satisfy two criteria:
The symptoms must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue.
For more detailed information regarding the definition of CFS, please go to our CFS Definition section.