creation date: 2026-02-03 16:49
tags: Pathologies
Fibromyalgia
Background
Definitions
Fibromyalgia is a chronic pain condition relating to central pain sensitization (nociplastic pain).
Etiology and Pathogenesis
There is no evidence that fibromyalgia arises from a singular event. It is believed that various physical and/or emotional stressors may trigger or aggravate the condition.
- Certain infections such as Lyme or viruses
- Emotional or physical trauma
- Sleep or mood disturbances (bidirectional)
- Concurrent rheumatic or MSK pain disorders
Fibromyalgia may also have a familial risk and epigenetic component.
The pathogenesis of fibromyalgia likely involves changes in:
Pain processing
- Increased central sensitivity to sensory stimuli
- Increased perception of pain (neuronal activity) following stimuli
- Decreased pain inhibition (endogenous analgesia deficiency)
- Increased pain receptors
Other central changes
- Increased glutamine and decreased GABA levels
- Decreased grey-matter in anterior cingulate cortex and prefrontal cortex
- Abnormal connectivity of pain pathways
Clinical Presentation
Signs & Symptoms
Widespread musculoskeletal pain
- Widespread/multisite pain with or without swelling
- May start localized before becoming widespread
- Intensity higher at rest or after movement
- Greater level of global impairment/impact
- May be accompanied by numbness, tingling, and burning
- Constant throughout the day which may also have morning stiffness
- Chronic (at least 3 months of persistence)
Fatigue
- Sense of exhaustion
- May be physical (eg. exercise intolerance and weakness) or mental (eg. brain fog)
- Out of proportion to amount of effort exerted
- Not relieved by rest
Sleep disturbances
- Sleeping lightly
- Waking frequently and difficulty returning to sleep
- Feeling of unrefreshed despite adequate time sleeping
Other symptoms
- Mood disturbances
- Cognitive disturbances
- Neurologic symptoms (headaches, paresthesias, autonomic nervous system dysfunction, small fibre neuropathy)
Physical findings
- Diffuse, widespread muscle and soft tissue tenderness
- Usually absent of swelling, erythema, or deformity
History & Physical Exam
A strong history and physical should elicit features of fibromyalgia.
Risk Factors
Diagnosis
Criteria
Diagnosis is made clinically in patients with consistent symptoms and in absence of features of alternative diagnosis:
- 3 months in duration
- Widespread pain
- Presence of other core features (sleep disturbances and fatigue)
Work-up
Workup consist of tests to rule out alternative diagnoses.
- CBC (r/o anemia of chronic disease, inflammatory disorders, occult connective tissue disorders)
- Comprehensive metabolic panel (baseline GFR for medication adjustments)
- ESR and/or CRP (r/o inflammatory disease)
- TSH (r/o hypothyroidism)
Additionally:
- Vitamin B12 (if cognitive disorder)
- Iron studies (if iron deficiency is suspected, even in absence of anemia)
Differential
Differential diagnoses include those that result in polyarthralgia.
Red Flags / Complications
Complications include impairment to daily quality of life. Decreased physical activity may increase the risk of metabolic syndrome.
Management
Non-pharmacological
Non-pharmacologic therapy is both first-line whether on its own or with pharmacotherapy.
Patient education
This consist of:
- Explanation of fibromyalgia including the non-inflammatory nature and the difference from classic nociceptive pain
- The impact of comorbidities and their treatment
- Sleep hygiene
Cognitive (psychological) therapy
Options may include:
- CBT
- Mindfulness-based stress reduction
- Meditation and relaxation
Increased activity and exercise
Exercise from cardiovascular fitness, resistance exercise, and movement therapies may be beneficial.
Pharmacological / Interventional
Pharmacotherapy is indicated for patients with moderate to severe symptoms or if the patient has mild symptoms that do not respond to nonpharmacological therapy.
Choice of medication depends on the presenting symptoms.
Diffuse, widespread pain without mood or sleep disturbances:
- Amitriptyline 5-10 mg PO daily 1-3 hours before bedtime
- Cyclobenzaprine 10-20 mg PO qHS
Severe fatigue and/or depression:
- Duloxetine 20-30 mg PO qAM with food
- Milnacipran 12.5 mg PO qAM
Severe sleep disturbance:
- Pregabalin 25-50 mg PO qHS, increasing dose by 25-50 mg every 2-4 weeks