II. Epidemiology
- Women account for more than 75-85% of Fibromyalgia patients (female gender RR 2-14)
 - Peak Incidence: ages 20 to 60 years old
- Incidence increases with age
 
 - Most common rheumatic cause of chronic diffuse pain
- Most common cause of Chronic Pain in women ages 20 to 55 years old
 
 - 
                          Incidence
                          
- Rheumatology patients: 15%
- Only Osteoarthritis is more common in rheumatology practice
 
 - General medical patients: 5%
 - General female population: 2-3%
 
 - Rheumatology patients: 15%
 
III. Pathophysiology
- Increased central sensitivity to peripheral Sensation (as with other functional pain syndromes)
 - Pain system dysfunction related to abnormalities in the forebrain
- Dysfunctional central nociceptive signal processing leading to hyperalgesia and Allodynia
 - Imbalance between excitatory and inhibitory Neurotransmitters including within the insula
 
 
IV. Risk Factors
- Post-Traumatic Stress Disorder (present in up to 45% of Fibromyalgia patients)
 - Sexual abuse or rape
 - Family History
 
V. Symptoms: General
- See Fibromyalgia Rapid Screening Tool
 - Chronic diffuse pain (100%)
- Predominant, core symptom
 
 - Severe Fatigue (81%)
 - Morning stiffness longer than 15 minutes (77%)
 - 
                          Sleep Disorder (75%)
- Difficulty falling asleep, staying asleep or frequent awakenings
 - Non-restorative sleep (alpha-delta sleep)
 - Sleep Apnea
 - Nocturnal Myoclonus
 - Restless Leg Syndrome
 
 - Atypical Paresthesias (63%)
 - Anxiety (48%)
 - Dry Mouth (36%)
 - Recurrent Headaches (53%)
 - Dysmenorrhea (41%)
 - Past History of Major Depression (31%)
 - Irritable Bowel Syndrome (30-70%)
 - Urinary urgency (26%)
 - Cold sensitivity or Raynaud's Phenomenon (17%)
 - Cognitive impact ("Fibro Fog)
- Decreased concentration and attention
 - Mental slowing
 
 
VI. Symptoms: Exacerbating Factors
- Post-exertional increase in Muscle pain
 - Emotional Stress or Abuse
 
VII. Signs
- See Diagnosis below
 - Diffuse soft tissue Tender Points
- Not associated with focal or generalized findings to suggest other rheumatologic cause
 - Joint inflammation, swelling or deformity suggests alternative diagnosis
 - However, Fibromyalgia may coexist with other Pain Disorders (see associated comorbid conditions below)
 
 
VIII. Labs
- Fibromyalgia is a clinical diagnosis and labs are not required in routine causes
- Labs are normal in isolated Fibromyalgia
 - Labs are often obtained to evaluate specific prominent symptoms (e.g. Fatigue)
 
 - Standard Evaluation
- Complete Blood Count (CBC, esp. Hemoglobin)
 - Basic Metabolic Panel (e.g. Chem8)
 - Thyroid Stimulating Hormone (TSH)
 
 - Additional tests when indicated (non-specific tests, order judiciously, when rheumatologic features are present)
- Erythrocyte Sedimentation Rate (ESR)
 - C-Reactive Protein (C-RP)
 - Antinuclear Antibody (ANA)
 - Rheumatoid Factor (RF)
 - Creatinine Phosphokinase (CPK)
 
 - Fibromyalgia specific testing
- FM/a Cytokine Array-based Test
- May be used to confirm Fibromyalgia Diagnosis
 - Test Sensitivity: 93%
 - Test Specificity: 89% (70% when patient has comorbid Rheumatologic Conditions)
 - Positive Likelihood Ratio: 3.1
 - Negative Likelihood Ratio: 0.1
 - Straub (2021) Am Fam Physician 103(9): 566-7 [PubMed]
 
 
 - FM/a Cytokine Array-based Test
 
IX. Diagnosis: General Criteria
- Fibromyalgia is a diagnosis of exclusion
 - Widespread musculoskeletal pain ("I hurt all over")
 - Regional: Each of 4 body quadrants involved
- Pain on left and right side of body
 - Pain above and below waist
 
 - Axial skeleton pain present
- Cervical Spine
 - Anterior chest
 - Thoracic Spine
 - Low back
 
 - Pain worse in the morning and at the end of the day
 - Moderate to severe Fatigue or sleep problems
 - Symptoms persist at least 3 months
 
X. Diagnosis: Specific Diagnostic Tools
- Screening
 - AAPT Criteria 2019 (alternative to ACR Criteria, Test Sensitivity 74%)
- Six of 9 painful sites (head, each arm, each leg, chest, Abdomen, upper back, lower back/buttocks)
 - Moderate to severe sleep problems or Fatigue
 - Pain present for 3 months or more
 - Arnold (2019) J Pain 20(6):611-628 +PMID: 30453109 [PubMed]
 
 - ACR Criteria Updates 2016 (Test Sensitivity 78-80%)
- Generalized pain in 4 of 5 regions for at least 3 months
 - Simplified Part 2 of the Symptom Severity Score
 - Incorporates Widespread Pain Index, symptom severity and Fatigue, sleep and cognitive impacts
 
 - ACR Criteria Updates 2010
 - ACR Original Criteria 1990
- See Tender Points (11 of 18 present)
 - Replaced by newer ACR and AAPT Criteria
 
 - References
 
XI. Associated Conditions: Augmented Pain and Sensory Processing Disorders
- Chronic Fatigue Syndrome
 - Tension Headache
 - Migraine Headache
 - Primary Dysmenorrhea
 - Restless Legs Syndrome
 - Periodic Limb Movement disorder
 - Temporomandibular Joint pain
 - Myofascial Pain Syndrome
 - Interstitial Cystitis
 - Irritable Bowel Syndrome
 - Endometriosis
 - Non-cardiac Chest Pain
 - Chronic Low Back Pain
 - Reduced functional ability
 - Aerobic deconditioning
 - Vulvodynia
 
XII. Associated Conditions: Common Comorbid Chronic Conditions
- Obstructive Sleep Apnea
 - Rheumatologic Conditions (may complicate Fibromyalgia Diagnosis)
 - Mental health disorders
- Post-Traumatic Stress Disorder
 - Major Depression (occurs in up to 50% of Fibromyalgia patients)
 - Bipolar Disorder
 - Generalized Anxiety Disorder
 - Substance Use Disorder
 
 
XIII. Differential Diagnosis
- Other Myofascial Conditions
- See Associated Conditions listed above
 - Myofascial Pain Syndrome
 - Chronic Fatigue Syndrome
 
 - Psychiatric Conditions
 - Rheumatic, Endocrine and Neurologic Conditions
- Systemic Lupus Erythematosus (SLE)
 - Rheumatoid Arthritis
 - Polymyalgia Rheumatica (esp. age >60 years old)
 - Polymyositis
 - Diabetes Mellitus
 - Myopathy or Neuropathy
 - Myotonic Dystrophy
 - Multiple Sclerosis
 - Hypothyroidism
 - Hyperparathyroidism
 - Ankylosing Spondylitis or other Spondyloarthropathy
 - Disc Herniation with radiculopathy
 - Paraneoplastic Neuropathy
 - Parkinson's Disease
 
 - Infectious Conditions
 - Medications
 - Miscellaneous Conditions
- Vitamin D Deficiency
 - Eosinophilia-Myalgia Syndrome (rare, likely toxin related, such as L-Tryptophan ingestion)
 
 
XIV. Management
- See Fibromyalgia Non-Pharmacologic Management
 - See Fibromyalgia Pharmacologic Management
 - Fibromyalgia Impact Questionnaire
- Assess for associated functional Impairment
 
 
XV. Resources: Patients
- Fransen (1997) Fibromyalgia Help Book, Smith House
 - Starlanyl (1996) Fibromyalgia and Myofascial Pain, NHP
 
XVI. Resources: Organizations
- Arthritis Foundation
 - National Fibromyalgia Research Association
 - USA Fibromyalgia Association
 - UK Fibromyalgia Association
 
XVII. References
- Money and Glauser (2017) Crit Dec Emerg Med 31(1): 15-21
 - Klippel (1997) Primer Rheumatic Diseases, p.124-7
 - Yunus (1996) Consultant, p. 1260-74
 - Yunus (1996) Consultant, p. 1279-85
 - Berman (1999) J Fam Pract 48(3):213-18 [PubMed]
 - Gremillion (1998) Phys Sportsmed, 26(4) 55-65 [PubMed]
 - Hadler (1997) Postgrad Med 102(2):161-77 [PubMed]
 - Kodner (2015) Am Fam Physician 91(7): 472-8 [PubMed]
 - Reiffenberger (1996) Am Fam Physician 53(5):1698-1704 [PubMed]
 - Wilke (1996) Postgrad Med 100(1):153-70 [PubMed]
 - Winslow (2023) Am Fam Physician 107(2): 137-44 [PubMed]