Four patients, all with chronic pain, and all with a diagnosis of fibromyalgia syndrome (FMS): which of these patients is actually suffering from this disorder? 

Fibromyalgia syndrome (FMS) remains an elusive condition of unknown etiology, in which patients report chronic widespread pain (allodynia or hyperalgesia) and a variety of other complaints including fatigue, sleep disorders, cognitive deficit, irritable bowel and bladder syndrome, headache, Raynaud’s syndrome, bruxism, atypical patterns of sensory dysethesia, and other symptoms.

Fibromyalgia syndrome (FMS) is a relatively new diagnostic entity that surfaced in the rheumatology literature in the late 20th century. Certain patients experienced widespread aches and pains not confined to any specific muscle or joint.