The pain is out of proportion to the apparent injury. That is the diagnosis, not an exaggeration. That is why most patients are not believed, and it is the inherent nature of neuropathic injury.

COMPLEX REGIONAL PAIN SYNDROME

Complex regional pain syndrome (CRPS) is pain far out of proportion to the original injury. It is produced by a nervous system that has changed how it processes signals from the limb, not by ongoing tissue damage. It is diagnosed by examining the limb against the Budapest criteria. It is not diagnosed by imaging or blood tests, which are normal.

The pain is out of all proportion to the injury. The limb looks and feels wrong. And somebody has probably implied you are exaggerating. You are not. This is a recognized condition with diagnostic criteria, and the criteria are what nobody applied.

The disproportion is the disease, not a red flag about you

This is the central fact. Almost everything that goes wrong for these patients follows from it. In CRPS the pain is enormously out of proportion to the observed tissue damage. Observed is the key word, because the tissue damage is often minor, healed, or was never impressive to begin with.

Take a clinician trained to expect pain to track injury. The clinician looks at a healed wrist fracture, a well-done release, or a scan showing nothing. The conclusion is that the reported pain cannot be coming from there. The reasoning is sound, but the premise is wrong. The pain is not coming from the tissue. It is coming from a nervous system that has changed how it processes signals from that limb.

Phantom limb is the clearest way to understand it

After an amputation, a substantial share of people feel severe pain in a limb that is no longer there. There is no tissue at all to be damaged. Yet the pain is real, severe and neuropathic (nerve-generated).

Nobody accuses those patients of exaggerating. That is because the missing limb makes the point beyond argument. Pain is made by the nervous system. It does not need ongoing tissue damage to be produced or to be severe.

CRPS is the same principle with the limb still attached. That is exactly why it is disbelieved. The limb is there, and it looks mostly intact. So the mismatch between how it looks and how it feels gets read as a problem with the patient. In fact it is the defining feature of the diagnosis.

What that means for how you are treated

It means the search for more tissue damage is usually futile. Repeat imaging, repeat scoping, another opinion on the original injury: all of it looks for something that is not the problem. And each normal result is quietly filed as more evidence against you.

It also means the diagnosis is made by examining the limb for the signs listed below, not by finding a lesion. That is not a weaker kind of diagnosis. It is the correct one for a condition of the nervous system.

What people are told, and what is actually happening

A wrist fracture that healed. A carpal tunnel release that went well on paper. A minor injury months ago. And a limb that is now burning, swollen, extremely sensitive to touch, and changing color and temperature in a way nobody can explain.

At that point the file starts to describe somebody whose symptoms exceed the findings. That is because the findings were never looked for. CRPS is diagnosed on a set pattern of signs: sensory, vasomotor (blood flow), sudomotor (sweating) and motor. It is not diagnosed on imaging, which is normal. It is not diagnosed on blood tests, which are normal.

How is CRPS diagnosed?

The criteria used worldwide require continuing pain out of proportion to the event that started it. They also require symptoms and observed signs across four categories.

• Sensory: oversensitivity to light touch, or pain from things that should not hurt. A sleeve, a breeze, water in the shower.
• Vasomotor: the limb changes color, or one side is measurably warmer or cooler than the other.
• Sudomotor / edema: swelling, or sweating that differs between sides.
• Motor / trophic: reduced range, weakness, tremor, and changes in hair, nail or skin growth.

Here is the difference that matters for diagnosis. Symptoms are what you report. Signs are what a clinician observes at the visit. You need both, in enough categories. That is why a visit where nobody looked at the limb properly cannot rule this out.

Why is CRPS so often missed?

Because it looks like something else first. Early CRPS after a hand or wrist procedure gets blamed on the operation not working. Burning arm pain gets called radiculopathy. Oversensitivity gets called a difficult patient.

And because it sits in exactly the group an upper-limb practice sees. These are people after a fracture, a release, a fusion, or an injury that seemed minor. Asking the four questions above takes two minutes. It makes the whole difference.

The evidence position, stated honestly

This is where most pages about CRPS become unreliable, so here is the uncomfortable version. A Cochrane review of CRPS treatments found that the certainty of evidence across most treatments is low or very low. That is not a reason to do nothing. It is a reason to be suspicious of anybody offering you a confident protocol.

What the guidelines do consistently support is early, graded return of function. That means movement, desensitization, mirror therapy and graded motor imagery. Interventional treatment is used to make that function possible, not as a treatment in itself. The rehab is the treatment. The injections buy a window in which it can happen.

What we do here

Establish the diagnosis properly against the criteria. That includes examining the limb for signs, not just taking a history and ordering a scan. Rule out the things that mimic it: an untreated nerve compression, an infection, a vascular problem, or an inflammatory arthropathy (inflammatory joint disease).

Then treat to enable function. A stellate ganglion block is the usual first interventional step for an upper limb. Where the condition is established and refractory (not responding to treatment), dorsal column stimulation is a considered option. It is not a first move.

The thing that changes the outcome most

Time to diagnosis. CRPS treated early, with the limb kept moving, does substantially better than CRPS that has spent a year being disbelieved. In that year the limb was protected and stopped being used.

That is the strongest argument on this page for getting it named. It is not because naming it is treatment. It is because protective disuse follows being disbelieved. That disuse is itself part of what locks the condition in.

Why does a CRPS limb turn warm or cold?

Early CRPS is often the warm, red, swollen version. The limb looks inflamed and feels hot. Later it more often becomes the cold, mottled, sweaty version with hair and nail changes. Both are the same condition at different points. Yet people are often told the second one cannot be CRPS because it does not look inflamed.

The temperature difference between sides is worth measuring, not guessing. It is one of the four categories the criteria ask about.

What makes CRPS worse?

• Immobilizing the limb. Slings, splints and protective disuse lock it in. This is the single most damaging piece of well-meant advice people receive.
• Repeated procedures aimed at the original injury, when that injury has healed and the problem is now the nervous system.
• Being disbelieved, which reliably leads to more guarding and less movement.
• Untreated sleep loss, which lowers pain thresholds and is almost universal here.

How is CRPS treated?

Restore movement from the first week. It is graded and often uncomfortable. Add desensitization work, and mirror therapy or graded motor imagery where indicated. Interventional treatment exists to make that possible on days when it otherwise would not be.

Medication is adjunctive (supporting), not central. And the metabolic terrain matters here as it does everywhere on this site. A nervous system trying to return to normal in the presence of insulin resistance and chronic inflammation is working uphill.

What people ask about CRPS

Is there a test that proves it?

No, and that is a feature of the condition, not a gap in your workup. It is a clinical diagnosis made against defined criteria. That is why the exam of the limb matters more than any scan. What the stellate ganglion block treats.

Does it spread?

It can involve other limbs in a minority of people. That is not inevitable. It is not a reason to stop using the affected one. Disuse is a bigger risk than spread. When the hands are the problem.

Will it go away?

Many cases improve substantially, particularly those treated early with a focus on restoring function. A share become long-standing. Anybody offering certainty in either direction is not being straight with you. Where spinal cord stimulation fits.

Is it psychological?

No. It is a disorder of the nervous system with physical signs you can observe. Being disbelieved for a year is psychologically damaging. That is a different statement, and a common one. What the stellate ganglion block treats.

What triggers complex regional pain syndrome?

It usually follows an injury or procedure on the limb: a wrist fracture, a carpal tunnel release, a fusion, or an injury that seemed minor at the time. The tissue often heals normally. What changes is the nervous system, which starts processing signals from that limb differently. That is why the pain continues long after the original damage has settled.

Is CRPS a real condition?

Yes. It is a recognized condition with diagnostic criteria used worldwide, the Budapest criteria. It has physical signs you can observe, such as color and temperature change, swelling and sweating differences between sides. Phantom limb pain makes the point: people feel severe pain in a limb that is no longer there. Pain comes from the nervous system. It does not need ongoing tissue damage to be real or severe.

What is the best treatment for CRPS?

Early, graded return of movement is the treatment: desensitization, mirror therapy or graded motor imagery, starting in the first week. Injections support that work rather than replace it. A stellate ganglion block is the usual first step for an arm. Spinal cord stimulation is an option for established cases that have not responded. Medication plays a supporting role. Evidence for most single treatments is low certainty, so be wary of confident protocols.

Related reading

• Stellate ganglion block
• Dorsal column stimulation
• When your hands are the problem
• Carpal tunnel hydrodissection
• EMG and nerve conduction studies
• Cervical radiculopathy