The concept of primary fibromyalgia (fibrositis): clinical value, relation and significance to other chronic musculoskeletal pain syndromes.

PFS, MPS and TMPDS can be identified using positive diagnostic criteria among patients presenting with chronic pain. A directed rather than exhaustive search for organic diseases known to coexist with these syndromes is usually all that is necessary. Criteria are presently empirical but do identify homogeneous populations of patients for study and treatment. Some patients, however, provide examples of overlap and it may be useful to think of CMPS in terms of the Venn diagram depicted in Fig. 2. In this report we have attempted an initial classification for a group of common and perplexing chronic pain disorders of the musculoskeletal system which at present have no identifiable cause. Previous investigations have been hampered by erroneous pathological concepts, heterogeneous patient populations and poor study design particularly with respect to treatment modalities. We hope that this classification, while empirical, will lead to needed epidemiological studies outlining the similarities and differences between these clinically observable and different musculoskeletal syndromes. We hope, further, that it will foster cooperation between different medical disciplines so that clinical biases might be tested in light of current concepts of the scientific method.