Idiopathic chronic fatigue and myalgia syndrome (myalgic encephalomyelitis): some thoughts on nomenclature and aetiology.

Myalgic encephalomyelitis is a misnomer that describes epidemics of probable hysterical illness and bears no definite relationship to chronic fatigue and myalgia syndrome. The relationship of idiopathic fatigue syndromes to fatigue syndromes after well-defined viral illnesses such as glandular fever is also unclear. Detailed studies of muscle histochemistry and biochemistry in idiopathic chronic fatigue and myalgia syndrome do not support a defect in intermediate metabolism. The aetiology of this syndrome is unknown and it is not yet clear whether it has an organic or a non-organic basis.