Last updated: May 19, 2022

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Fibromyalgia (FM) is a neurosensory disorder characterized by chronic musculocutaneous pain. The etiology and pathogenesis of this condition are not fully understood, but, notably, there is no identifiable inflammation that causes the musculocutaneous symptoms. Patients typically present with functional symptoms (e.g., fatigue, unrefreshing sleep, morning stiffness) and often have a history of psychiatric disorders (e.g., depression, generalized anxiety disorder). Physical examination reveals characteristic tender points over multiple areas of the body with no signs of inflammation (i.e., no notable swelling, deformity, or erythema). Findings from laboratory tests are normal. Although this disorder is benign, it causes patients significant psychological strain and discomfort. Treatment focuses on lifestyle changes and multidisciplinary pain management.

Epidemiological data refers to the US, unless otherwise specified.

The pathophysiology of FM is not fully understood, but its etiology is likely multifactorial. The interaction of the following factors may play a role: [3]

  • Genetic predisposition
  • Autoimmune [4]
  • Environmental triggers (e.g., physical or psychosocial stress)
  • Dysregulation of the neuroendocrine and autonomic nervous systems

Common symptoms

Common associations

The following disorders can manifest with symptoms that sometimes resemble those seen in FM, and these conditions may occur alongside FM.

  • FM is a clinical diagnosis. ; [7][8][9]
    • The 2016 American College of Rheumatology (ACR) criteria take into account:
      • Symptom duration of at least 3 months
      • Patient self-reporting using the fibromyalgia score :
        • Widespread pain or tenderness in up to 19 different regions of the body (widespread pain index; WPI)
        • Presence and severity of symptoms such as fatigue, sleep disturbance, depression, headache, and cognitive impairment (symptom severity scale)
        • Self-reporting criteria are met if WPI ≥ 7 and SSS ≥ 5 OR WPI 4–6 and SSS ≥ 9
      • Presence of generalized pain, i.e., pain in ≥ 4 regions (upper left, upper right, axial, lower left, lower right)
    • Traditionally, a tender-point examination was performed based on the 1990 ACR diagnostic criteria:
      • Symptom duration of at least 3 months
      • Tender points: ≥ 11 of 18 FM-associated localized areas of pain
      • Pain-affected areas: all four quadrants of the body
  • Laboratory values (e.g., ESR) and imaging findings are normal (helpful for excluding other causes or comorbidities).

A combined assessment of the number, duration, and severity of cognitive and somatic symptoms provides the most accurate diagnosis.

Myofascial pain syndrome

  • Definition: : a chronic pain syndrome caused by muscle tension, injury, or repetitive motion and characterized by the presence of trigger points in muscles and/or fascia (small tender knots) [10]
  • Clinical features
    • Pain is mostly confined to one anatomical region: fewer tender points compared to FM (≤ 11 of 18)
    • Leads to weakness and limited range of motion
    • Jump sign (myofascial pain syndrome): A physical examination finding characterized by an involuntary, sudden jerk or wince in response to stimulation of a tender area or trigger point (not seen in FM).
    • Fatigue, headache, and sleep disturbances are less frequent compared to FM
  • Treatment: physical therapy, massage, stretching, ice packs, NSAIDs


The differential diagnoses listed here are not exhaustive.

Initial approach


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  3. Arout CA et al.. Gender Differences in the Prevalence of Fibromyalgia and in Concomitant Medical and Psychiatric Disorders: A National Veterans Health Administration Study. Journal of Women's Health. 2018; 27 (8): p.1035-1044. doi: 10.1089/jwh.2017.6622 . | Open in Read by QxMD
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  7. Warren JW, Langenberg P, Clauw DJ. The number of existing functional somatic syndromes (FSSs) is an important risk factor for new, different FSSs. J Psychosom Res. 2012; 74 (1). doi: 10.1016/j.jpsychores.2012.09.002. . | Open in Read by QxMD
  8. New and Modified Fibromyalgia Diagnostic Criteria. Updated: February 8, 2012. Accessed: April 12, 2017.
  9. Fibromyalgia Diagnosis. Updated: January 1, 2017. Accessed: April 12, 2017.
  10. CDC - Fibromyalgia Fact Sheet. Updated: March 13, 2017. Accessed: April 12, 2017.
  11. Wolfe F, Clauw DJ, Fitzcharles M-A, et al. 2016 Revisions to the 2010/2011 fibromyalgia diagnostic criteria. Semin Arthritis Rheum. 2016; 46 (3): p.319-329. doi: 10.1016/j.semarthrit.2016.08.012 . | Open in Read by QxMD

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