Their life falls apart. The condition affects 3 to 7 million Americans, most commonly in women between 20-40 years old. It is not clear if these conditions tend to co-exist with fibromyalgia, are caused by fibromyalgia, or if fibromyalgia and these conditions appear similar. The cause of fibromyalgia is unknown. It is also thought that genetic factors may play a role.
Some researchers suspect abnormalities in muscle tissue, whereas others propose a viral cause.
A variety of factors seem to trigger the illness in susceptible individuals. These triggers include viral illnesses, trauma, chronic sleep disturbance, and emotional distress. The formal criteria of the American College of Rheumatology require that tenderness be present in at least eleven of eighteen classic sites. However in our experience, atypical cases are fairly common so these criteria should be considered guidelines rather than strict criteria. The condition should be diagnosed by an experienced clinician who will look for a constellation of symptoms together with the multiple areas of muscle tenderness.