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Complex regional pain syndrome (CRPS)
CRPS is prolonged pain out of proportion to the injury, with changes in sensation, blood vessels, sweating and swelling, and movement — the diagnosis is clinical by the Budapest criteria, and the central treatment is movement and active rehabilitation, not immobilisation.
Why it matters in the exam
Type I CRPS occurs without proven nerve injury, and type II — after a nerve injury. Common triggers: a fracture (especially a distal radius fracture), surgery, a sprain and stroke ("shoulder-hand syndrome"). The Budapest criteria: continuing pain out of proportion to the event; at least one symptom in three of four categories — sensory (hypersensitivity, allodynia), vasomotor (temperature and skin colour differences), sudomotor and oedema, and motor and trophic changes (weakness, tremor, reduced range, hair, nail and skin changes); at least one sign on examination in two or more categories; and no other diagnosis that explains the picture.
Tests are not needed for diagnosis, but a three-phase bone scan can show increased periarticular uptake in the late phase, and X-ray may show patchy osteopenia. Prevention: after a wrist fracture there are studies in which vitamin C (500 mg a day for 50 days) reduced CRPS, but the evidence is mixed. Treat early: physiotherapy and occupational therapy with desensitisation, "stress loading", graded motor imagery and mirror therapy; avoid immobilisation.
Drugs: a short course of corticosteroids in the early stage (especially after stroke), bisphosphonates in the early stage, gabapentin or pregabalin and antidepressants for neuropathic pain, and NSAIDs. Sympathetic blocks (stellate ganglion for the upper limb and lumbar sympathetic for the lower) can allow exercise when pain prevents it. For refractory pain — spinal cord stimulation. Psychological support matters, because fear of movement worsens immobility and the syndrome.
Key points
- Disproportionate pain with autonomic and motor changes.
- Budapest: symptoms in 3 of 4, signs in 2 of 4.
- Common trigger: distal radius fracture.
- Central treatment: active rehabilitation, not immobilisation.
- Early steroids or a bisphosphonate; sympathetic block to allow exercise.
Summary table
| Category | Symptoms and signs | Example |
|---|---|---|
| Sensory | Hypersensitivity, allodynia | Pain from the light touch of a sheet |
| Vasomotor | Temperature and colour difference | A warm red hand or a cold bluish one |
| Sudomotor and oedema | Swelling, sweating difference | A swollen, sweaty hand |
| Motor and trophic | Weakness, tremor, reduced range, skin and hair changes | Stiff fingers, brittle nails |
| Diagnosis | Budapest: symptoms in 3 of 4, signs in 2 of 4 | No other diagnosis |
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Sources
- IASP Budapest diagnostic criteria for CRPS, 2010 (validation) — Clinical diagnostic criteria
- Complex Regional Pain Syndrome: Practical Diagnostic and Treatment Guidelines (RSDSA), 5th edition (2022) — Rehabilitation-centred treatment algorithm
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.