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Definition

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:

  1. Have severe chronic fatigue of six months or longer duration with other known medical conditions excluded by clinical diagnosis; and
  2. Concurrently have four or more of the following symptoms: substantial impairment in short-term memory or concentration; sore throat; tender 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 lasting more than 24 hours.

The symptoms must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue.

The 1988 chronic fatigue syndrome (CFS) working case definition (Holmes, et al) did not effectively distinguish CFS from other types of unexplained fatigue. For this reason, it was decided during a 1993 meeting of CFS investigators to develop a logical revision of that definition. The ensuing effort led to the 1994 definition. Following years of use of the 1994 definition a working group prepared the following document:

Other Commonly Observed Symptoms in CFS

In addition to the eight primary defining symptoms of CFS, a number of other symptoms have been reported by some CFS patients. The frequencies of occurrence of these symptoms vary from 20% to 50% among CFS patients. They include abdominal pain, alcohol intolerance, bloating, chest pain, chronic cough, diarrhea, dizziness, dry eyes or mouth, earaches, irregular heartbeat, jaw pain, morning stiffness, nausea, night sweats, psychological problems (depression, irritability, anxiety, panic attacks), shortness of breath, skin sensations, tingling sensations, and weight loss. These symptoms do not contribute to the diagnosis of CFS.

Page last modified on May 3, 2006


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