Complex Regional Pain Syndrome (CRPS)
Complex regional pain syndrome is a condition in which pain after an injury becomes far more severe and prolonged than the injury would explain, usually affecting a hand, arm, foot, or leg. Alongside the pain there are changes in the limb itself — differences in temperature or color, swelling, sweating, altered sensitivity, stiffness, and sometimes changes to hair, skin, or nails. It can follow a significant injury or a minor one, and occasionally none at all. Early recognition matters more here than in most pain conditions, because keeping the limb moving is central to treatment and immobilizing it makes things worse. Diagnosis is clinical, based on the pattern of signs and symptoms.
What CRPS is
A disorder of how the nervous system responds to injury, involving pain processing, the autonomic nervous system, inflammation, and the brain's representation of the limb.
The defining feature is disproportion. The pain, and the changes in the limb, are out of proportion to whatever started it.
- It can follow a minor injury. A sprain, a small fracture, or a routine operation. The severity of CRPS bears no relationship to the severity of what caused it.
- Sometimes there's no identifiable trigger at all, which doesn't make the diagnosis less valid.
Signs cluster in four groups, and diagnosis is based on a pattern across them:
- Sensory — pain from light touch, increased pain from normally painful stimuli
- Vasomotor — temperature or color differences between the limbs
- Sudomotor or edema — swelling, or differences in sweating
- Motor or trophic — reduced movement, weakness, tremor, or changes to hair, skin, or nails
CRPS was previously called reflex sympathetic dystrophy or causalgia. Those terms are largely retired.
Why early movement matters
This is the most important practical point on the page, and it runs against instinct.
The natural response to a painful limb is to protect it — hold it still, avoid using it, keep it covered. In CRPS, that protection makes things worse.
Treatment therefore aims at keeping the limb used and moving, at whatever level is tolerable, from as early as possible. That is hard, and it needs support. Being told to move a limb that hurts to touch is not a small request, and it works best with a therapist who understands the condition.
What treatment involves
Rehabilitation is the core, and it's usually multidisciplinary.
- Graded movement and use — keeping the limb in the picture, restoring function progressively.
- Desensitization — graduated exposure to touch and texture, so the limb tolerates contact again.
- Graded motor imagery — a staged approach working through recognizing limb laterality, imagined movement, and then mirror therapy. It targets the brain's representation of the limb, which is affected in CRPS.
- Mirror therapy — using a mirror so the affected limb appears to move normally. Unusual-sounding, and with a real evidence base in this condition.
- Pain education — understanding the mechanism supports engagement with movement that hurts.
- Psychological support — CRPS is distressing, frightening, and frequently disbelieved. Support is offered because the condition is hard, not because the pain is psychological.
- Medical management — several approaches exist, and this is a conversation for a pain specialist. Referral to a specialist pain service is appropriate, particularly where symptoms aren't improving.
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Goals worth setting
Tolerate a sock on that foot · Put my hand in my pocket · Wash the affected limb myself · Use the hand to hold a cup · Walk without a crutch
Reduce pain · Improve range of motion
What to expect
- Outcomes vary considerably. Many people improve substantially, particularly with early treatment. Some have persistent symptoms.
- Progress is usually slow and non-linear, and flares are part of the course rather than a sign of failure.
- Being believed is a recurring problem. The signs can fluctuate, and a limb that looks normal in clinic may have looked very different that morning. Photographs of the limb during a flare are genuinely useful to bring to appointments.
Frequently asked questions
What is complex regional pain syndrome?
A condition where pain after an injury becomes far more severe and prolonged than the injury explains, with changes in the limb's temperature, color, swelling, sensitivity, and movement.
Can CRPS follow a minor injury?
Yes. A sprain, small fracture, or routine operation can trigger it, and the severity of CRPS bears no relationship to the severity of what caused it. Occasionally there's no identifiable trigger.
Should I rest the limb?
No — and this is the most important point. Immobilization is associated with worse outcomes. Keeping the limb moving and in use, at whatever level is tolerable, is central to treatment.
What is graded motor imagery?
A staged rehabilitation approach working through limb laterality recognition, imagined movement, and mirror therapy. It targets the brain's representation of the limb, which is affected in CRPS.
Does mirror therapy really work?
It has a real evidence base in CRPS. Using a mirror so the affected limb appears to move normally addresses the altered representation of the limb.
Why does light touch hurt so much?
Allodynia — pain from stimuli that shouldn't be painful — is characteristic. It reflects sensitization in how the nervous system processes touch, and it's one of the most disabling features.
Will CRPS go away?
Outcomes vary. Many improve substantially, particularly with early treatment. Early recognition and early movement are the factors most associated with better outcomes.
Related
Pain and chronic conditions · Pacing and activity management · Fibromyalgia · Occupational therapy
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Disclaimer. For general educational purposes; not medical advice, diagnosis, or treatment. Seek prompt assessment if pain after an injury is disproportionate or the limb has changed in color, temperature, or swelling.