Chronic Fatigue Syndrome
Chronic fatigue syndrome (CFS) is one of several names given to a poorly understood, highly debilitating disorder of uncertain etiology, which is thought to affect approximately 4 per 1,000 adult in the United States and other industrialized countries, and a smaller fraction of adolescents.
The disorder is marked by severe, chronic mental and physical exhaustion, arising in a previously healthy and active person, as well as other specific symptoms. Despite promising avenues of research, there remains no objective assay or pathological finding which is widely accepted to be diagnostic of CFS, and it remains a diagnosis of exclusion, made on the basis of patient history and symptomatic criteria. Although there is agreement on the genuine threat to health, happiness, and productivity posed by CFS, various physicians' groups, researchers, and patient activists champion very different nomenclature, diagnostic criteria, etiologic hypotheses, and favored treatments, resulting in ongoing controversy about nearly all aspects of this enigmatic disorder. Even the name chronic fatigue syndrome is controversial, with some patient advocates and other authorities preferring terms such as myalgic encephalomyelitis ("ME" or "ME/CFS") and post-viral fatigue syndrome ("PVFS"), which imply specific underlying etiologies or pathologic processes
CFS is not the same as "chronic fatigue” - while fatigue as a symptom is very common, CFS itself is relatively rare by comparison Most definitions (other than the 1991 UK Oxford criteri) require a number of features, the most common being severe mental and physical exhaustion which is "unrelieved by rest" (according to the 1994 Fukuda definition) and may be worsened by even trivial exertion (a mandatory diagnostic criterion according to some systems). Most diagnostic criteria insist that the symptoms must be present for at least six months, and all insist on there being no other cause for the fatigue: i.e. the fatigue must be idiopathic, not caused by other medical conditions such as diabetes, hypothyroidism or anemia. CFS patients may report many other symptoms which are not included in all diagnostic criteria, including muscle weakness, cognitive dysfunction, hypersensitivity, orthostatic intolerance, digestive disturbances, depression, poor immune response, and cardiac and respiratory problems. It is unclear if these symptoms represent co-morbid conditions or are produced by the same underlying etiology as CFS itself Some cases resolve or improve over time, and treatments (though none are universally accepted) bring a degree of improvement to many others.
CFS occurs more often, but not exclusively, in women, for unknown reasons. CFS is most easily diagnosed when formerly active adults become ill, and is most commonly diagnosed in young to middle aged adults, although it is also reported in adolescents and the elderly.