Fibromyalgia and related conditions.

Fibromyalgia is the currently preferred term for widespread musculoskeletal pain, typically accompanied by other symptoms such as fatigue, memory problems, and sleep and mood disturbances, for which no alternative cause can be identified. Earlier there was some doubt about whether there was an "organic basis" for these related conditions, but today there is irrefutable evidence from brain imaging and other techniques that this condition has strong biological underpinnings, even though psychological, social, and behavioral factors clearly play prominent roles in some patients. The pathophysiological hallmark is a sensitized or hyperactive central nervous system that leads to an increased volume control or gain on pain and sensory processing. This condition can occur in isolation, but more often it co-occurs with other conditions now being shown to have a similar underlying pathophysiology (eg, irritable bowel syndrome, interstitial cystitis, and tension headache) or as a comorbidity in individuals with diseases characterized by ongoing peripheral damage or inflammation (eg, autoimmune disorders and osteoarthritis). In the latter instance, the term centralized pain connotes the fact that in addition to the pain that might be caused by peripheral factors, there is superimposed pain augmentation occurring in the central nervous system. It is important to recognize this phenomenon (regardless of what term is used to describe it) because individuals with centralized pain do not respond nearly as well to treatments that work well for peripheral pain (surgery and opioids) and preferentially respond to centrally acting analgesics and nonpharmacological therapies.