II. Epidemiology

  1. Women account for more than 75-85% of Fibromyalgia patients (female gender RR 2-14)
  2. Peak Incidence: ages 20 to 60 years old
    1. Incidence increases with age
  3. Most common rheumatic cause of chronic diffuse pain
    1. Most common cause of Chronic Pain in women ages 20 to 55 years old
  4. Incidence
    1. Rheumatology patients: 15%
      1. Only Osteoarthritis is more common in rheumatology practice
    2. General medical patients: 5%
    3. General female population: 2-3%

III. Pathophysiology

  1. Increased central sensitivity to peripheral Sensation (as with other functional pain syndromes)
  2. Pain system dysfunction related to abnormalities in the forebrain
    1. Dysfunctional central nociceptive signal processing leading to hyperalgesia and Allodynia
    2. Imbalance between excitatory and inhibitory Neurotransmitters including within the insula

IV. Risk Factors

V. Symptoms: General

  1. See Fibromyalgia Rapid Screening Tool
  2. Chronic diffuse pain (100%)
    1. Predominant, core symptom
  3. Severe Fatigue (81%)
  4. Morning stiffness longer than 15 minutes (77%)
  5. Sleep Disorder (75%)
    1. Difficulty falling asleep, staying asleep or frequent awakenings
    2. Non-restorative sleep (alpha-delta sleep)
    3. Sleep Apnea
    4. Nocturnal Myoclonus
    5. Restless Leg Syndrome
  6. Atypical Paresthesias (63%)
  7. Anxiety (48%)
  8. Dry Mouth (36%)
  9. Recurrent Headaches (53%)
  10. Dysmenorrhea (41%)
  11. Past History of Major Depression (31%)
  12. Irritable Bowel Syndrome (30-70%)
  13. Urinary urgency (26%)
  14. Cold sensitivity or Raynaud's Phenomenon (17%)
  15. Cognitive impact ("Fibro Fog)
    1. Decreased concentration and attention
    2. Mental slowing

VI. Symptoms: Exacerbating Factors

  1. Post-exertional increase in Muscle pain
  2. Emotional Stress or Abuse

VII. Signs

  1. See Diagnosis below
  2. Diffuse soft tissue Tender Points
    1. Not associated with focal or generalized findings to suggest other rheumatologic cause
    2. Joint inflammation, swelling or deformity suggests alternative diagnosis
    3. However, Fibromyalgia may coexist with other Pain Disorders (see associated comorbid conditions below)

VIII. Labs

  1. Fibromyalgia is a clinical diagnosis and labs are not required in routine causes
    1. Labs are normal in isolated Fibromyalgia
    2. Labs are often obtained to evaluate specific prominent symptoms (e.g. Fatigue)
  2. Standard Evaluation
    1. Complete Blood Count (CBC, esp. Hemoglobin)
    2. Basic Metabolic Panel (e.g. Chem8)
    3. Thyroid Stimulating Hormone (TSH)
  3. Additional tests when indicated (non-specific tests, order judiciously, when rheumatologic features are present)
    1. Erythrocyte Sedimentation Rate (ESR)
    2. C-Reactive Protein (C-RP)
    3. Antinuclear Antibody (ANA)
    4. Rheumatoid Factor (RF)
    5. Creatinine Phosphokinase (CPK)
  4. Fibromyalgia specific testing
    1. FM/a Cytokine Array-based Test
      1. May be used to confirm Fibromyalgia Diagnosis
      2. Test Sensitivity: 93%
      3. Test Specificity: 89% (70% when patient has comorbid Rheumatologic Conditions)
      4. Positive Likelihood Ratio: 3.1
      5. Negative Likelihood Ratio: 0.1
      6. Straub (2021) Am Fam Physician 103(9): 566-7 [PubMed]

IX. Diagnosis: General Criteria

  1. Fibromyalgia is a diagnosis of exclusion
  2. Widespread musculoskeletal pain ("I hurt all over")
  3. Regional: Each of 4 body quadrants involved
    1. Pain on left and right side of body
    2. Pain above and below waist
  4. Axial skeleton pain present
    1. Cervical Spine
    2. Anterior chest
    3. Thoracic Spine
    4. Low back
  5. Pain worse in the morning and at the end of the day
  6. Moderate to severe Fatigue or sleep problems
  7. Symptoms persist at least 3 months

X. Diagnosis: Specific Diagnostic Tools

  1. Screening
    1. See Fibromyalgia Rapid Screening Tool
  2. AAPT Criteria 2019 (alternative to ACR Criteria, Test Sensitivity 74%)
    1. Six of 9 painful sites (head, each arm, each leg, chest, Abdomen, upper back, lower back/buttocks)
    2. Moderate to severe sleep problems or Fatigue
    3. Pain present for 3 months or more
    4. Arnold (2019) J Pain 20(6):611-628 +PMID: 30453109 [PubMed]
  3. ACR Criteria Updates 2016 (Test Sensitivity 78-80%)
    1. Generalized pain in 4 of 5 regions for at least 3 months
    2. Simplified Part 2 of the Symptom Severity Score
    3. Incorporates Widespread Pain Index, symptom severity and Fatigue, sleep and cognitive impacts
  4. ACR Criteria Updates 2010
    1. See ACR Fibromyalgia Diagnostic Criteria (ACRFDC)
    2. Widespread Pain Index replaced Tender Points
  5. ACR Original Criteria 1990
    1. See Tender Points (11 of 18 present)
    2. Replaced by newer ACR and AAPT Criteria
  6. References
    1. Salaffi (2020) Rheumatology 59(10): 3042-9 [PubMed]

XI. Associated Conditions: Augmented Pain and Sensory Processing Disorders

XIII. Differential Diagnosis

  1. Other Myofascial Conditions
    1. See Associated Conditions listed above
    2. Myofascial Pain Syndrome
    3. Chronic Fatigue Syndrome
  2. Psychiatric Conditions
    1. Masked Major Depression
    2. Somatoform Disorder
  3. Rheumatic, Endocrine and Neurologic Conditions
    1. Systemic Lupus Erythematosus (SLE)
    2. Rheumatoid Arthritis
    3. Polymyalgia Rheumatica (esp. age >60 years old)
    4. Polymyositis
    5. Diabetes Mellitus
    6. Myopathy or Neuropathy
    7. Myotonic Dystrophy
    8. Multiple Sclerosis
    9. Hypothyroidism
    10. Hyperparathyroidism
    11. Ankylosing Spondylitis or other Spondyloarthropathy
    12. Disc Herniation with radiculopathy
    13. Paraneoplastic Neuropathy
    14. Parkinson's Disease
  4. Infectious Conditions
    1. Epstein-Barr Virus (Mononucleosis)
    2. Parvovirus
    3. Q Fever
    4. Lyme Disease
    5. Viral Hepatitis
  5. Medications
    1. Statin-Induced Myopathy
    2. Bisphosphonates
    3. Aromatase Inhibitors
    4. Chronic Opioids
  6. Miscellaneous Conditions
    1. Vitamin D Deficiency
    2. Eosinophilia-Myalgia Syndrome (rare, likely toxin related, such as L-Tryptophan ingestion)

XIV. Management

  1. See Fibromyalgia Non-Pharmacologic Management
  2. See Fibromyalgia Pharmacologic Management
  3. Fibromyalgia Impact Questionnaire
    1. Assess for associated functional Impairment

XV. Resources: Patients

  1. Fransen (1997) Fibromyalgia Help Book, Smith House
    1. Paid link to Amazon.com (ISBN 0961522143)
  2. Starlanyl (1996) Fibromyalgia and Myofascial Pain, NHP
    1. Paid link to Amazon.com (ISBN 1572240466)

XVI. Resources: Organizations

  1. Arthritis Foundation
    1. http://www.arthritis.org
  2. National Fibromyalgia Research Association
    1. http://www.teleport.com/~nfra
  3. USA Fibromyalgia Association
    1. http://www.fibromyalgiaassnusa.org
  4. UK Fibromyalgia Association
    1. http://www.community-care.org.uk/charity/fmauk.html

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