Fibromyalgia syndrome

To the Editor: Littlejohn has presented to readers of the Journal the current construct of fibromyalgia as proposed by the American College of Rheumatology (ACR).1,2 However, not only has he taken liberties with that construct, but he has failed to identify major problems with it. Littlejohn asserts that fibromyalgia is not a diagnosis of exclusion. In almost the same breath he states that it can co-exist with other disorders, especially painful ones such as "regional pain problems (including low back and pelvic pain syndromes and other similar syndromes)" (our italics). Further perusal of the clinical features reveals an anthology of complaints, including "an overlap with chronic fatigue syndrome". Therefore, the construct of fibromyalgia is so broad as to include almost every chronic pain state, thereby constituting a tautology. 3 How, then, is it possible to diagnose "nonfibromyalgia"? By departing from the ACR definition and including syndromes of localised or regional pain under the fibromyalgia banner, Littlejohn compounds the problem of tautology, thus making a parody of the exercise of differential diagnosis. There is no doubt that the clinical problem of diffuse musculoskeletal pain accompanied by mechanical allodynia (pain in response to a stimulus which is never noxious) exists. Littlejohn's assertion that this is a "disorder of function of the pain system" begs the question of whether there is such a system, rather than acknowledging the complex relationship between nociception (pain sense) and the psychosocial influences which lead to the distress and disability that characterise chronic pain." The evidence of altered nociception in patients with fibromyalgia may reflect central sensitisation," but whether this arises from "central pain modulatory factors" or from sustained peripheral nociceptive input cannot be determined from our current state of knowledge. The real damage from the clinical application of the flawed construct of fibromyalgia has only just begun to be appreciated." Its tautological nature allows it to be invoked in medicolegal settings using the fallacious proposition ofpost hoc ergo propter hoc. While fibromyalgia remains unlinked to a cogent theory of pathogenesis, and as long as understanding of clinical phenomena is