The term chronic fatigue syndrome may be applied to a patient whose persistent tiredness lacks a physical pathology to account for it. The diagnosis of neurasthenia was popular in the late nineteenth century, and its symptoms included fatigue after minimal effort, loss of interest, irritability, poor concentration, and sleep disturbance.
Similar syndromes have attracted great interest in recent years under new names such as chronic fatigue syndrome, post-viral syndrome, and myalgic encephalomyelitis (ME). There is an association with chronic pain and 'fibromy-lagia', on the one hand, and with psychiatric disturbance including anxiety and depression, on the other hand. However, there is no agreed physical basis for these conditions; for example, no objective inflammation or other pathology ('-itis') of the muscles or brain has been found to justify the use of the term encephalomyelitis.
Some cases follow infection with the Epstein-Barr virus (which causes infectious mononucleosis or glandular fever) or other viral illnesses such as influenza, hepatitis, brucellosis, or encephalitis. In other cases, no such infection can be identified, leading to controversy about whether chronic fatigue is primarily 'organic' or 'functional' in origin. Many cases probably represent the combination of the after-effects of a viral infection with a psychogenic reaction to stress in a person with obsessional and perfectionist personality traits.
Some patients present after many years of overwork, in jobs where they may have been overpromoted on the basis of their diligence, but beyond their intrinsic capabilities. Their inability to maintain this after a minor health problem is probably best not seen in medical terms.
Many patients have depressive symptoms, but it is not clear whether these are part of the syndrome itself, or a secondary reaction to it. Whatever the aetiology, psychosocial factors appear to be of prime importance in maintaining persistent symptoms and disability. Some patients, convinced that they are suffering from continuing viral illness, insist on continuing to rest, and this causes loss of fitness and eventually makes fatigue worse. Others are willing to engage in a programme of gradually increasing activity, although they are often reluctant to consider that their problems may have a psychological dimension.
Cognitive-behavioural treatment and graded exercise have been shown to be effective in randomized trials. Other proposed treatments such as 'pacing', based on prolonged rest periods, are not supported by this level of evidence, although they are popular with some patient groups (Reid et al., 2006).
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