Abstract
Objective: Although a consensus view of classification criteria has been obtained, major questions remain as to exactly "what" is fibromyalgia. In addition, the best way to diagnose, as opposed to classify, fibromyalgia has not been fully addressed. Findings: Depending on the author, fibromyalgia has been considered to have major characteristics of 1. a pain disorder, 2. a psychological disorder, 3. a muscle disorder, or 4. a biopsychosocial complex. The most commonly held view supports the pain or biopsychosocial construct. Clinical criteria are proposed and are less restrictive than classification criteria. Conclusions: Studies should be performed using less restrictive criteria to obtain information regarding the course of the syndrome and to understand how fibromyalgia develops. Additional population of clinical studies are required to identify and understand subsets within the fibromyalgia construct.