Complex Regional Pain Syndrome
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Direct answer
Complex regional pain syndrome is a chronic, disproportionate pain disorder of a limb, usually triggered by minor injury, fracture, surgery or immobilisation. It is diagnosed clinically by the Budapest criteria: continuing pain out of proportion to the trigger, symptoms in at least three of four categories, signs in at least two categories, and no better explanation. Early mobilisation and physiotherapy remain the cornerstone of treatment.
What you must remember
- Budapest criteria: continuing pain disproportionate to the inciting event, symptoms in three of four categories, signs in two or more categories at evaluation, and no alternative diagnosis.
- Type I and type II: type I occurs without an identifiable nerve lesion, while type II (causalgia) follows a documented injury to a major nerve.
- Classic triggers: distal radius fracture is the textbook upper limb trigger and ankle fracture the lower limb one, and road traffic injuries are a common source in Indian practice.
- Early features: burning pain, allodynia, oedema, colour and temperature change and altered sweating; late features include skin thinning, stiffness and muscle wasting.
- Diagnosis is clinical: no single test confirms the condition, and plain films may show patchy demineralisation while bone scintigraphy is only supportive.
- First-line treatment: graded motor imagery, mirror therapy and active physiotherapy, with NSAIDs or gabapentinoids for pain.
- Adjuncts: bisphosphonates have some support in early disease, while sympathetic blocks or spinal cord stimulation are reserved for refractory cases.
Graded rehabilitation after a wrist fracture
A 34-year-old woman develops burning pain, swelling and colour change in the hand six weeks after a Colles fracture. The pain is far worse than the fracture ever was. Rehabilitation is the main lever in this case, so the correct option almost always keeps the limb moving.
- Confirm the features: Document pain disproportionate to the injury, then check oedema, temperature and colour asymmetry, along with allodynia or hyperalgesia.
- Exclude mimics: Rule out infection, deep vein thrombosis, tendon rupture, non-union and nerve compression before settling on this diagnosis.
- Start active movement early: Begin graded active range-of-motion exercises rather than prolonged immobilisation, because disuse feeds the cycle.
- Add graded motor imagery: Progress from left and right limb recognition to imagined movement, and finally to mirror therapy.
- Treat the pain: NSAIDs or gabapentinoids help symptoms, and corticosteroids are sometimes used in the early inflammatory phase.
- Escalate when refractory: Sympathetic blocks, neuromodulation or a pain clinic referral are considered when rehabilitation stalls.
Where the exam tries to catch you
NEET-PG stems give a fracture history and a pain pattern that tempts you toward a scan-based answer.
- Trap: choosing bone scintigraphy as the confirmatory test. Correct: CRPS is a clinical diagnosis under the Budapest criteria, and a scan only supports it.
- Trap: immobilising the limb until the pain settles. Correct: prolonged immobilisation sustains the disease, so early graded movement is the right answer.
- Trap: labelling every post-fracture ache as CRPS. Correct: the pain must be disproportionate and unexplained by infection, thrombosis or non-union first.
Frequently asked questions
Which criteria are used to diagnose complex regional pain syndrome?
The Budapest criteria are used to diagnose complex regional pain syndrome. They require continuing pain out of proportion to the inciting event, symptoms and signs in defined categories, and exclusion of other causes.
What is the difference between complex regional pain syndrome type I and type II?
Complex regional pain syndrome type I occurs without an identifiable nerve injury, and was earlier called reflex sympathetic dystrophy. Complex regional pain syndrome type II, also called causalgia, follows a documented injury to a major nerve.
Which investigation supports a diagnosis of complex regional pain syndrome?
No single test confirms complex regional pain syndrome, so the diagnosis rests on clinical criteria. Radiographs may show patchy demineralisation, and bone scintigraphy shows supportive periarticular uptake but is not diagnostic.
Why does early mobilisation matter in complex regional pain syndrome?
Immobilisation and disuse worsen the inflammatory and sympathetic cycle that sustains complex regional pain syndrome. Early graded active movement is therefore preferred over prolonged plaster or rest in exam answers.
Which drugs are first-line for pain in complex regional pain syndrome?
NSAIDs and gabapentinoids are the usual first-line drugs for pain in complex regional pain syndrome, as standard textbook care. Bisphosphonates have some support in early disease, and evidence for other agents is limited and varies between sources.