Fibromyalgia syndrome, a problem of tautology.

Fibromyalgia syndrome is generally taken to denote a clinical state of widespread musculoskeletal pain, stiffness, and fatigue but its pathophysiology, physical and psychological, is unknown, and the nature of the diagnostically mandatory "tender points" remains obscure. Diagnostic criteria convey no pathophysiological insight and they have been "validated" via a circular argument in which the evidence on which the construct is based is taken as proof of its veracity. The concept of fibromyalgia syndrome is valid only in the sense that it includes all possibilities. An alternative approach to this very real clinical presentation is via secondary hyperalgesia.