Fibromyalgia

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.

• Prevalence: 2–3% ^[1]
• Sex: : ♀ > ♂ (2:1) ^[2]
• Peak incidence: : 20–50 years (risk of occurrence increases with age)

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

• Chronic, widespread pain, primarily at points where muscles and tendons attach to bone (tender points)
• Headache, fatigue
• Morning stiffness
• Unrefreshing sleep
• Cognitive dysfunction (known as fibro fog), e.g., poor memory, difficulty concentrating, and lack of clarity of thought ^[5]
• Paresthesias
• Autonomic dysfunction: digestive problems, weight fluctuation, palpitations, sexual dysfunction, night sweats

Common associations

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

• Functional somatic syndromes (e.g., chronic fatigue syndrome, irritable bowel syndrome, tension or migraine headaches, chronic pelvic and bladder syndromes) ^[6]
• Psychiatric disorders (depression, generalized anxiety disorder)
• Sleep disorders (e.g., sleep movement disorders such as restless leg syndrome)
• Inflammatory rheumatic diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis) ^[3]

• 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

Other

• Polymyalgia rheumatica
• Hypothyroid myopathy
• Complex regional pain syndrome
• Sleep apnea
• Rheumatoid arthritis
• Systemic lupus erythematosus
• Malignancy
• See also “Differential diagnoses of myopathies.”

The differential diagnoses listed here are not exhaustive.

Initial approach

• Patient education: Explain that the condition, though painful, is benign, and recommend coping strategies such as relaxation exercises.
• Lifestyle changes: regular physical activity, dietary recommendations, sleep hygiene
• Medication
  • Initially monotherapy: low-dose tricyclic antidepressants (TCA, e.g., amitriptyline), selective serotonin-norepinephrine reuptake inhibitors (e.g., duloxetine), or anticonvulsants (e.g., pregabalin, gabapentin)
  • Avoid narcotic medications (e.g., opioids)
• Consider comorbidities (e.g., sleep disorders) in treatment planning

Nonresponders

• Multidisciplinary management (e.g., with rheumatology, psychiatry) and adequate pain management
  • Psychological interventions (e.g., cognitive-behavioral therapy)
  • Physiotherapy (e.g., stretching, hydrotherapy, and heat application)
• Combination therapy with the drugs mentioned above