Prolonged pain, disproportionate to the initiating event, most frequently following minor trauma and most commonly affecting the distal aspect of an extremity.
Pain often described as spontaneous, burning, lancinating, sharp, shooting, or electric. Characteristically develops dull, boring, and aching qualities with chronicity. Allodynia and hyperalgesia are almost always present.
Local oedema, erythema, sweating abnormalities, and trophic skin and nail changes are often, but not always, present.
The affected extremity is often held immobile, and this can be associated with dystonia, focal weakness, and contractures.
Diagnosis is clinical. No specific tests are diagnostic; investigations may be useful to support the diagnosis or rule out alternative pathology.
The treatment goal is functional restoration of a limb by using adequate pain management techniques, with patient education, physiotherapies, pharmacotherapy, and appropriate psychological techniques tailored to the individual patient.
Complex regional pain syndrome (CRPS) is defined as continuing (spontaneous and/or evoked) regional pain that is out of proportion to the severity of the inciting event and beyond the normal time frame expected following the event. The pain is usually regional (not in a specific nerve territory or dermatome) and has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings with variable progression over time.
History and exam
Key diagnostic factors
- presence of risk factors
- chronic pain
- limb pain with radiation
- allodynia and hyperalgesia
- body scheme changes
- trophic skin and nail changes
- erythema or bluish appearance
- local sweating changes or sweating asymmetry
- muscle weakness
Other diagnostic factors
- dystonic posturing
- sensory loss in glove and stocking distribution
- local changes in hair growth
- skin bullae
- female sex
- other inciting event
1st investigations to order
- no test required: diagnosis is clinical
Investigations to consider
- nerve conduction studies with surface electrodes
- punch skin biopsy
- radiograph of affected limb
- bone scintigraphy with technetium 99m
- dual-energy x-ray absorptiometry (DXA)
- quantitative CT scan
- MRI testing
- vascular studies
- sympathetic nerve blocks
- intravenous regional anaesthetic blocks
- quantitative sensory testing
- laser Doppler flowmetry
- sweat (sudomotor) tests
early CRPS (within 6 months of onset)
chronic CRPS (>6 months since onset)
- Arterial compromise
- Bone pathology
- Neuropathic pain in adults: pharmacological management in non-specialist settings
- Standards for the diagnosis and management of complex regional pain syndrome
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