Fibromyalgia
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Direct answer
Widespread body pain lasting more than three months with severe fatigue, unrefreshing sleep and cognitive complaints, in a patient whose inflammatory markers, autoimmune serology and imaging are normal, defines fibromyalgia, a disorder of central pain processing rather than a joint or muscle disease. The 2016 revision of the ACR criteria uses the Widespread Pain Index and the Symptom Severity Scale: a WPI of at least 7 with an SSS of at least 5, or a WPI of 4 to 6 with an SSS of at least 9, classifies the condition. Management rests on education, graded aerobic exercise and sleep hygiene, with pregabalin, duloxetine or milnacipran as pharmacologic anchors and a firm refusal to escalate opioids.
What you must remember
- The 1990 criteria required 11 of 18 defined tender points on thumb-pressure; they are still viva favourites although no longer needed for diagnosis.
- The 2016 criteria: WPI 7 or more with SSS 5 or more, or WPI 4 to 6 with SSS 9 or more, with symptoms present at a similar level for at least three months.
- The Symptom Severity Scale scores fatigue, unrefreshed sleep and cognitive symptoms each 0 to 3, plus the count of somatic symptoms.
- Associated features: female predominance of about 8 or 9 to 1, irritable bowel syndrome, tension-type headache, temporomandibular dysfunction, restless legs and mood disorder.
- Secondary fibromyalgia coexists with rheumatoid arthritis, systemic lupus erythematosus and ankylosing spondylitis, where widespread pain out of proportion to objective disease should raise the thought.
- First-line drugs: pregabalin 150 to 450 mg daily, duloxetine 30 to 60 mg daily, milnacipran, and low-dose amitriptyline 10 to 25 mg at night for sleep; paracetamol and NSAIDs are largely ineffective.
- Non-drug measures outrank drugs: graded aerobic exercise, cognitive behavioural therapy, sleep hygiene and weight management form the base of every guideline.
How to work through a typical clinic case
A 38-year-old woman reports body-wide pain for two years, worst in the neck, lower back and both hips, with exhaustion, night-time awakening and mental fog that her family attributes to attitude. Examination shows soft-tissue tenderness across the trapezii, medial knee fat pads and greater trochanters, but no synovitis, weakness or rash. ESR, CRP, TSH, vitamin D and a full blood count are normal.
Step one: confirm the diagnosis positively. Score the Widespread Pain Index across the 19 defined body regions and the SSS as above; she scores WPI 9 and SSS 8, satisfying the 2016 criteria outright.
Step two: exclude the treatable mimics with a focused panel rather than a blind autoimmunity fishing trip: thyroid function, calcium, vitamin D, iron studies, and a creatine kinase where myalgia is prominent. ANA is ordered only when lupus is clinically suspected, since low-titre positivity is common in healthy people.
Step three: explain the mechanism, because the diagnosis is therapeutic. Telling the patient that the volume control of the pain system is turned up, that the muscles and joints are not being damaged, and that sleep and mood feed the pain loop reduces catastrophising more than any prescription.
Step four: prescribe in layers. Start graded aerobic exercise such as walking or swimming, building duration before intensity; add sleep hygiene and treatment of the restless legs or sleep apnoea if present; then choose a drug matched to comorbidity, duloxetine with depression, pregabalin with anxiety and sleep disruption, amitriptyline at night when insomnia dominates.
Step five: review expectations and function. Flares follow stress and poor sleep; the goal is function, not pain zero; referral to pain psychology and phased return to work outperform repeat investigations. Opioids, benzodiazepines and repeated steroid courses have no role.
Where the exam tries to catch you
The recurring scenario is over-investigation: a woman with widespread pain, a normal examination and normal basic tests, where the wrong option is an ever-expanding autoimmunity panel and the right one is applying the criteria. The mirror-image trap is under-diagnosis in established rheumatic disease, where new widespread pain with normal inflammatory markers in a stable rheumatoid patient is fibromyalgia overlay rather than a flare, and escalating immunosuppression harms rather than helps. Viva examiners also enjoy the drug list question, expecting the answer that pregabalin, duloxetine and milnacipran are the guideline agents and that simple analgesics fail because the problem is central sensitisation, not peripheral inflammation.
Frequently asked questions
What are the 2016 ACR criteria thresholds?
Widespread Pain Index 7 or more with Symptom Severity Scale 5 or more, or WPI 4 to 6 with SSS 9 or more, for at least three months.
How many tender points did the 1990 criteria require?
Eleven of eighteen specified points on approximately 4 kg of thumb pressure.
Which three drugs are the guideline pharmacologic anchors?
Pregabalin, duloxetine and milnacipran, with low-dose amitriptyline widely used at night for sleep.
Which non-drug measure has the strongest evidence?
Graded aerobic exercise, alongside cognitive behavioural therapy and sleep hygiene.
Why do NSAIDs not work in fibromyalgia?
Because the pain arises from central sensitisation of pain processing without peripheral inflammation, so anti-inflammatory pathways are not the target.