see also:

• wikipedia
• rheumatology

• During the 1980s, the term fibromyalgia came to the forefront in rheumatology and orthopedics.
• A condition found predominantly in women, fibromyalgia is defined as a chronic, diffuse, musculoskeletal pain and a sleep disorder, without evidence of arthritis or myositis. The literature initially focused on the extremities and trunk, but the head and neck are now included in the condition. Many patients presenting for treatment of masticatory muscle pain report other areas of rheumatic pain in anamnestic questionnaires, and they commonly have disturbed sleep, including bruxism. Currently, we diagnose myogenic pain as masticatory or head and neck fibromyalgia. This is often one component of generalized fibromyalgia involving the back, abdomen, or extremities. We apply the same treatment concepts to the head and neck as those advocated for fibromyalgia of the lower quadrants.

• diagnosed roughly three times more often in women than in men

• believed by many to be a primary autonomic nervous system dysfunction and is grouped as one of the dysautonomia syndromes
• a 2026 genome study of 2.5 million people¹⁾ suggests that it is most likely a neurologic problem rather than auto-immune
  • 26 genetic variants identified that were linked to patients diagnosed as having fibromyalgia
    • the one most strongly linked to fibromyalgia risk was within the gene HTT
      • other mutations in this gene cause Huntington's disease, a severe, progressive and fatal neurodegenerative disorder
    • another genetic variant pointed to a receptor called GPR52 that regulates HTT levels
  • genes near these fibromyalgia genetic risk factors were more active in nervous system cells than in other types of cells
    • appears to also show a substantial genetic overlap between fibromyalgia and a range of other conditions, including low back pain, irritable bowel syndrome, and post-traumatic stress disorder

• no current diagnostic tests available and hence it is currently a clinical diagnosis
• 2019 AAPT (ACTTION–American Pain Society Pain Taxonomy) criteria:
  • at least 3 months of pain in at least 6 of 9 anatomic regions
  • moderate to severe sleep problems or fatigue
• 2016 ACR Diagnostic Criteria
  • all three of the following conditions need to be met:
    • Widespread Pain Index (WPI) and Symptom Severity (SS) score thresholds
      • WPI ≥7 and SS score ≥5, or, WPI 4–6 and SS score ≥9
    • generalized pain:
      • pain must be present in at least 4 of 5 body regions (left upper, right upper, left lower, right lower, and axial).
      • jaw, chest, and abdominal pain are not included in the generalized pain definition
    • duration:
      • symptoms have been present at a similar level for at least 3 months.
  • Widespread Pain Index (WPI)
    • the WPI counts the number of areas (out of 19) in which the patient has had pain over the last week. The 19 areas are distributed across five regions:
      • Left upper: jaw (left), shoulder girdle (left), upper arm (left), lower arm (left)
      • Right upper: jaw (right), shoulder girdle (right), upper arm (right), lower arm (right)
      • Left lower: hip/buttock/trochanter (left), upper leg (left), lower leg (left)
      • Right lower: hip/buttock/trochanter (right), upper leg (right), lower leg (right)
      • Axial: neck, upper back, lower back, chest, abdomen
  • Symptom Severity (SS) Scale
    • the SS scale score (0–12) is the sum of:
      • severity (0–3 each) over the past week of:
        • fatigue
        • waking unrefreshed
        • cognitive symptoms
      • number of additional symptoms (0–1 each) over the previous 6 months:
        • headaches
        • pain or cramps in lower abdomen
        • depression

• Ix: no imaging needed
• Rx: NSAIDs, muscle relaxants, flat-plane splint, behavioural Rx