Fibromyalgia is the diagnosis given to individuals with chronic widespread musculoskeletal pain for which no alternative cause, such as tissue inflammation or damage, can be identified. Fibromyalgia is now believed to be, at least in part, a disorder of central pain processing that produces heightened responses to painful stimuli (hyperalgesia) and painful responses to nonpainful stimuli (allodynia). Aberrations in central pain processing may also be partly responsible for symptoms experienced in several chronic pain disorders that coaggregate with fibromyalgia, which is itself a product of genetic and environmental factors. Thus, aberrational central pain processing is implicated in irritable bowel syndrome, temporomandibular disorder, chronic low back pain, and certain other chronic pain disorders. Fibromyalgia and related disorders appear to reflect deficiencies in serotonergic and noradrenergic, but not opioidergic, transmission in the central nervous system. The heightened state of pain transmission may also be owing to increases in pronociceptive neurotransmitters such as glutamate and substance P. In some cases, psychological and behavioral factors are also in play. Although the overlapping symptomatology between fibromyalgia and related disorders may present diagnostic challenges, proper examination and observation can help clinicians make an accurate diagnosis. In recent years, the vastly improved understanding of the mechanism underlying fibromyalgia and the related spectrum of diseases has fostered rapid advances in the therapy of these chronic pain disorders by both pharmacologic and nonpharmacologic interventions.
(c) 2009 Elsevier Inc.