Fibromyalgia (FM or FMS) is characterised by chronic widespread pain and allodynia (a heightened and painful response to pressure). Fibromyalgia symptoms are not restricted to pain, leading to the use of the alternative term fibromyalgia syndrome for the condition. Other symptoms include debilitating fatigue, sleep disturbance, and joint stiffness. Some people also report difficulty with swallowing, bowel and bladder abnormalities, numbness and tingling, and cognitive dysfunction. Fibromyalgia is frequently associated with psychiatric conditions such as depression and anxiety and stress-related disorders such as posttraumatic stress disorder. Not all people with fibromyalgia experience all associated symptoms.
Its exact cause is unknown but is believed to involve psychological, genetic, neurobiological and environmental factors. There is evidence that environmental factors and certain genes increase the risk of developing fibromyalgia – these same genes are also associated with other functional somatic syndromes and major depressive disorder. The central symptom of fibromyalgia, namely widespread pain appears to result from neuro-chemical imbalances including activation of inflammatory pathways in the brain which results in abnormalities in pain processing. The brains of fibromyalgia patients show functional and structural differences from those of healthy individuals, but it is unclear whether the brain anomalies cause fibromyalgia symptoms or are the product of an unknown underlying common cause. Some research suggests that these brain anomalies may be the result of childhood stress, or prolonged or severe stress.