Subgroups in Fibromyalgia

A Contemporary Overview of Fibromyalgia

Robert M. Bennett, M.D.
Oregon Health Sciences University

Fibromyalgia is a syndrome of chronic widespread pain. It is a construct developed by rheumatologists to account for a common group of patients that they see in their routine practice. Indeed, fibromyalgia subjects account for 20-30% of rheumatology referrals. Epidemiological studies suggest that fibromyalgia is at one end of a spectrum of chronic widespread pain and is defined in terms of such pain plus 11 or more out of 18 tender points. The overall prevalence of fibromyalgia is 3-10%, with a 10:1 predominance in women.

The clinical spectrum of fibromyalgia is much more than a pain syndrome and commonly includes fatigue, headaches, irritable bowel syndrome, irritable bladder, restless legs, neurally mediated hypotension, psychological distress and varying levels of dysfunction. There is compelling evidence that the pain and accompanying symptoms are a manifestation of amplified sensory processing at the level of the spinal cord and brain – “central sensitization.” The disordered neurophysiology and molecular events underlying central sensitization are now being unraveled.

The events leading to the development of fibromyalgia commonly include other pain states, injuries, infections, inflammatory diseases and persistent stress. Why only a minority of people experiencing such problems go on to develop fibromyalgia involves familial, genetic and environmental influences. The possibility that congenital abnormalities of the hindbrain (Chiari I malformation) are a possible predisposing influence is of great interest to rheumatologists and patients alike. Irrespective of pathogenesis, chronic pain states have profound secondary effects in terms of altered neuroendocrine function, disordered sleep, psychological distress (especially depression) and maladaptive behavioral changes. Until there are more effective treatments for central sensitization, the mainstays of fibromyalgia treatment will continue to be pain medications, cognitive behavioral therapy, gentle exercise, minimization of peripheral pain generators (e.g., myofascial trigger points), treatment of depression and disturbed sleep.

Presented at the National Fibromyalgia Research Association's Subgroups in Fibromyalgia Symposium, September 26-27, 1999, in Portland, Oregon.