• Nonarticular, noninflammatory form of muscular and joint pain more common in females:
    • Widespread pain from stimuli that do not normally cause pain (allodynia)
    • >11 diffuse tender points
    • Fatigue
    • Sleep disturbance
    • Muscle stiffness
    • Difficulties with attention, memory
    • Limited physical findings
  • Fibromyalgia is no longer a diagnosis of exclusion, may occur with other rheumatic diseases


  • Mechanism:
    • Painful symptoms believed to result from greater activation of pronociceptive (pain-causing) system relative to antinociceptive (pain-dampening) system in brain and spinal cord
  • Abnormalities identified as possible mechanism:
    • Increased substance P (facilitates pronociception)
    • Decreased biogenic amines (NE, serotonin, dopamine), which facilitate antinociception
    • Decreased gray matter in brain
    • Genetics: 1/3 of patients with fibromyalgia have a close relative who is affected:
      • Candidate genes include 5-HT2A, serotonin transporter, D4 receptor, others
    • Like many complex diseases, psychological factors play a role, with high incidence of psychiatric disorders
    • In genetically predisposed individuals, likely starts as initial insult from age, trauma, illness, inflammation, etc.
    • Hypothalamus–pituitary–adrenal axis stress-response dysfunction has been indicated to precede development of fibromyalgia

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