Fibromyalgia, chronic fatigue syndrome, and myofascial pain syndrome.

Two important studies in which nuclear magnetic resonance spectroscopy was used convincingly demonstrated that muscle is not the primary pathologic factor in fibromyalgia. There were further studies reporting that fibromyalgia-chronic fatigue syndrome may follow well treated Lyme disease or mimic Lyme disease. The longest therapeutic trial to date in fibromyalgia demonstrated an initial modest effect of tricyclic medications, but at 6 months that efficacy was no longer evident. Investigation in both fibromyalgia and chronic fatigue syndrome now focuses on the central nervous system. The use of new technology, eg, neurohormonal assays and imaging such as single-photon emission computed tomography scan, may be important in understanding these elusive conditions.