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A 44-year-old woman presents with a 7-month history of widespread, migrating, deep aching pain across her neck, upper and lower back, chest wall and all four limbs. She describes profound fatigue, waking unrefreshed every morning despite adequate hours in bed, and difficulty concentrating at work ('brain fog'). She also has irritable-bowel-type bloating and intermittent headaches. She feels low in mood. There is no joint swelling, morning stiffness over 30 minutes, fever, weight loss or neurological deficit. Examination reveals tenderness to firm pressure at multiple soft-tissue sites but no synovitis, weakness or sensory loss. FBC, ESR, CRP, renal and liver function, CK, TSH and vitamin D are all normal.
Questions
a) What is the most likely diagnosis, and on what basis is it made? Give the criteria. (3 marks)
The most likely diagnosis is fibromyalgia, a chronic central sensitisation (nociplastic) pain syndrome. It is a clinical diagnosis using the ACR 2016 criteria: the Widespread Pain Index (WPI) at least 7 and Symptom Severity Scale (SSS) at least 5, OR WPI 4 to 6 and SSS at least 9; symptoms present at a similar level for at least 3 months; and a fibromyalgia diagnosis may coexist with other conditions. Here she has widespread axial and bilateral pain for over 3 months with fatigue, unrefreshing sleep, cognitive dysfunction and somatic co-symptoms, and normal examination and investigations excluding mimics. No tender-point counting is required (the old 1990 method is abandoned).
b) List four investigations you would perform to exclude organic mimics, and state why each. (3 marks)
- TSH — to exclude hypothyroidism, a classic mimic of fibromyalgia (fatigue, myalgia, constipation, cold intolerance).
- ESR and CRP — to exclude inflammatory rheumatic disease and polymyalgia rheumatica (normal in fibromyalgia; markedly raised in PMR/RA/vasculitis).
- CK — to exclude myopathy/polymyositis (normal in fibromyalgia; raised with proximal weakness in myositis).
- ANA, rheumatoid factor and anti-CCP — only if clinical features suggest SLE or rheumatoid arthritis; a low-titre ANA is non-specific. FBC, renal/liver function and vitamin D round out the baseline. No imaging is required without red flags.
c) Outline the stepwise management, emphasising the first-line evidence-based approach and naming two appropriate adjunct drugs and one class to avoid. (3 marks)
- First-line (non-pharmacological, most effective): patient education and validation (the pain is real but reflects a sensitised nervous system, not tissue damage); graded aerobic exercise (the single best-evidenced intervention); cognitive behavioural therapy (CBT); and sleep hygiene with stress management and pacing.
- Pharmacological adjuncts (chosen by predominant symptom, lowest effective dose, periodically reviewed): duloxetine (an SNRI, useful for pain with comorbid depression) and low-dose amitriptyline 10 to 25 mg nocte (for pain with dominant sleep disturbance); pregabalin/gabapentin are alternatives.
- AVOID strong opioids — ineffective for nociplastic pain, they cause opioid-induced hyperalgesia, tolerance and dependence. Corticosteroids and immunosuppressants have no role in primary fibromyalgia. Treat comorbid depression/anxiety actively.
d) What is the expected prognosis, and name two predictors of poorer outcome? (1 mark)
Fibromyalgia is a chronic, fluctuating condition that does not shorten life expectancy or cause organ damage or joint destruction; complete cure is uncommon but meaningful improvement in function is achievable. Predictors of poorer outcome include severe baseline pain and disability, comorbid depression/anxiety, ongoing opioid use, low social support, and passive coping.