Fatigue syndrome chronic
syndrome of unknown cause, characterised by clinically evaluated, unexplained persistent or relapsing chronic fatigue of at least six months' duration which is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction of previous levels of occupational, educational, social, or personal activities. Common concurrent symptoms (of six months duration) include impairment of memory or concentration, diffuse pain, sore throat, tender lymph nodes, headaches of a new type, pattern, or severity, and unrefreshing sleep. The aetiology is suspected to be viral or immunologic. There are suggestions that chronic fatigue syndrome (sometimes called myalgic encephalomyelitis) may be identical to neurasthenia and fibromyalgia.