Fibromyalgia, chronic fatigue syndrome, and myofascial pain syndrome.

The prevalence of chronic widespread pain in the general population in Israel was comparable with reports from the USA, UK, and Canada. Comorbidity with fibromyalgia (FM) resulted in somatic hyperalgesia in patients with irritable bowel syndrome. One sixth of the subjects with chronic widespread pain in the general population were also found to have a mental disorder. Mechanisms involved in referred pain, temporal summation, muscle hyperalgesia, and muscle pain at rest were attenuated by the N-methyl-D-aspartate (NMDA) antagonist, ketamine, in FM patients. Delayed corticotropin release, after interleukin-6 administration, in FM was shown to be consistent with a defect in hypothalamic corticotropin-releasing hormone neural function. The basal autonomic state of FM patients was characterized by increased sympathetic and decreased parasympathetic systems tones. The severity of functional impairment as assessed by the Medical Outcome Survey Short Form (SF-36) discriminated between patients with widespread pain alone and FM patients. Chronic fatigue syndrome (CFS) occurred in about 0.42% of a random community-based sample of 28,673 adults in Chicago, Illinois. A significant clinical overlap between CFS and FM was reported. Cytokine dysregulation was not found to be a singular or dominant factor in the pathogenesis of CFS. A favorable outcome of CFS in children was reported; two thirds recovered and resumed normal activities. No major therapeutic trials in FM and CFS were reported over the past year.