The Bone Healed. The Hand Did Not: Understanding Complex Regional Pain Syndrome

What this video covers

• Why CRPS is diagnosed by exam using the Budapest criteria, and why no scan or blood test can confirm it
• The leading theories, from nerve-driven inflammation to a blurred brain map of the limb. Why they are still proposed mechanisms, several backed mainly by animal work, not tests we can run on you
• How a sympathetic block — stellate ganglion for the arm, lumbar sympathetic for the leg — is used as a test and a rehab window, not a cure
• What the 2023 Cochrane overview found: no high-certainty evidence for any CRPS therapy. And moderate-certainty evidence that lidocaine sympathetic blocks probably do not beat placebo for pain
• What the only five-year randomized trial of spinal cord stimulation in CRPS type I showed. It was no better than physical therapy alone on pain or any other outcome. The effect faded over time. Yet 95 percent of implanted patients would do it again
• Why graded rehab is still the backbone of care
• MEDICAL DISCLAIMER: This content is for educational purposes only and is not medical advice. It does not substitute for professional diagnosis or treatment. Always consult a licensed healthcare provider regarding your condition. Viewing this video does not establish a doctor-patient relationship.

Complex regional pain syndrome is diagnosed clinically with the Budapest criteria. That means pain far out of proportion to the injury. It also means changes in the limb’s feeling, blood flow and color, sweating and swelling, and movement and growth of skin, hair and nails. No MRI, bone scan, thermogram or blood test confirms it.

Six weeks after a wrist fracture, the cast comes off. The bone has healed and the X-ray is normal. But the hand that comes out is not a hand that healed. It is swollen and glossy, blotchy red or dusky blue, and warmer than the other hand — or colder. The hair on the back of it grows coarser and the nails faster. A bedsheet is unbearable. And in a seven-minute visit, the patient is told that the fracture is healed, so this should settle down.

It does not settle down. That picture is complex regional pain syndrome — pain far out of proportion to the first injury. It comes with changes in feeling, blood flow, sweating, and growth in the limb. This article explains what is thought to be happening in the limb. It shows how those proposed mechanisms line up with what you feel. It explains why no scan can confirm the diagnosis. And it covers what that means for how you should be evaluated.

What causes complex regional pain syndrome?

Four mechanisms are proposed for complex regional pain syndrome. It matters a great deal that the word is proposed.

Neurogenic inflammation and microvascular dysfunction. Small nerve fibers in the limb release inflammatory signals too much and for too long. Fluid leaks out of tiny blood vessels into the tissue. That causes swelling and abnormal blood flow. This mechanism matches most directly what you can see: the swelling and the color change.

Sympathetic-afferent coupling. The sympathetic nervous system — the branch that controls blood vessel tone and sweating — starts driving pain fibers directly. This has been shown mainly in animals. Where it applies in people, it seems to be present in only some patients. It is not a universal explanation.

Dorsal horn sensitization. The relay station in the spinal cord where limb signals are first handled becomes overactive. So ordinary input arrives turned up. This is mostly lab and animal work.

Altered cortical representation. The brain keeps a map of the body. In complex regional pain syndrome, the part of that map for the affected hand or foot seems to fade and blur into its neighbors. This shows up in group imaging studies. But its role as a cause is uncertain. It may be a result rather than a cause.

Here is the part that gets left out: not one of these four is measurable in you, as an individual, in a clinic. They are ways to understand a syndrome, not tests. If a treatment is being justified to you based on one of them, treat it as a theory.

What are the symptoms of CRPS, and what does the pain feel like?

This condition feels so strange — and is so hard to describe to a doctor — because it is not one symptom. It is four families of symptoms showing up together in one limb.

• Sensory. Hyperalgesia (something painful hurts far more than it should) and allodynia (something that should not hurt at all — a sock, a bedsheet, moving air — hurts). This is what a sensitized spinal cord and a blurred brain map would be expected to cause. The volume on that limb has been turned up and the tuning has been lost.
• Vasomotor. One limb is warmer or colder than the other, and the skin color changes. That is the blood-flow half of the story. It is also why the limb warms when its sympathetic nerve supply is blocked with numbing drug. That warming shows the injection reached the sympathetic chain. It is not, by itself, proof that the injection treats the pain.
• Sudomotor and edema. Swelling and changed sweating. Fluid leaking into tissue is the proposed reason for the glossy, puffy limb.
• Motor and trophic. Weakness, tremor, dystonia (abnormal muscle tightening), and changes in hair, nail, and skin growth. The nails growing faster is not in your head. It is a growth change, and it belongs in the record.

That combination is the diagnosis. It is also why the condition is so easy to brush off one symptom at a time.

How is CRPS diagnosed with the Budapest criteria?

No imaging study and no blood test confirms complex regional pain syndrome. Not an MRI, not a bone scan, not a thermogram. If a doctor tells you a scan made this diagnosis, the research does not support that. The condition is still widely called reflex sympathetic dystrophy, or RSD, in older charts and in most patient talk. The same rule applies under either name.

The diagnosis is made by exam, using a set tool: the Budapest criteria. There are four categories: sensory, vasomotor, sudomotor and edema, and motor and trophic. A doctor needs reported symptoms in three of the four categories. The doctor needs signs seen on exam in two of the four. And — the part that gets skipped — there must be no other diagnosis that better explains the picture.

That discipline has been measured. Harden and colleagues wrote in Pain in 2010. They tested these criteria in 113 patients with CRPS type I and 47 with other nerve pain.¹ Take the older International Association for the Study of Pain criteria. Their sensitivity was 1.00, at a specificity of 0.41. That means they caught almost everyone who had the condition. But they also caught 59 percent of the people who did not. The Budapest clinical criteria keep sensitivity at 0.99 and raise specificity to 0.68. The stricter research version reaches 0.79 specificity, at lower sensitivity.

That jump — 0.41 to 0.68 — is the difference between a label and a diagnosis. Note who was studied, too. These criteria were tested in CRPS type I. Most trials in this condition enrolled type I only.

Why is CRPS so often missed or misdiagnosed?

Complex regional pain syndrome is mishandled in both directions at once. Both errors cost the same thing: time.

Some patients wait a year to hear the words. Their limb pain gets blamed on anxiety or being out of shape. Or each symptom is handled on its own — the swelling by one doctor, the burning by another. So nobody puts the pattern together. Meanwhile the limb is used less every week.

Other patients get the label in ten minutes because a limb looked red. Then they are treated forever for a disease they may not have. This is where the skipped part matters. Before this label goes on, a doctor should rule out other causes. These include infection, a deep vein clot, skin infection, a hidden fracture, and a bone that never healed. A pinched nerve, a radiculopathy, or a nerve injury should be found or ruled out. That is done by exam and, when needed, by electrodiagnostic testing (nerve tests). Inflammatory arthritis and poor artery blood flow should be considered.

Those tests do not confirm the condition. They subtract the alternatives. That is a different job. It is the one that gets skipped when a diagnosis is made from across the room.

The third thing standard care misses is the clock. Often the only offer is more and more medicine, and no medicine retrains a limb. The treatment with the strongest claim on your outcome is graded rehabilitation of that limb, started early and pushed steadily. That means graded motor imagery, mirror therapy, desensitization, and loading that builds over time. Be exact about what that sentence means. It says where the priority belongs. Rehab is the only part of the plan aimed straight at getting the limb working again. It does not claim proven benefit. The 2023 Cochrane overview found no high-certainty evidence that any therapy works here. Rehab is not exempt.² What is not in doubt is the cost of delay. Think of a month spent waiting for a diagnosis, or on shots that never end. That is a month the limb spends learning not to move.

How is CRPS evaluated and treated at the Padda Institute?

The framework used at the Padda Institute is simple to state. Make the diagnosis properly. Then use procedures to open a window that rehab fills.

Sympathetic blocks as a diagnostic probe. The right candidate meets the Budapest criteria and is still limited despite active rehab. It is not just anyone who happened to be offered an injection. If the arm is affected, the sympathetic supply is blocked at the stellate ganglion in the lower neck, at the C6 or C7 level. This is done under high-resolution ultrasound. Ultrasound shows the carotid, the inferior thyroid artery, the vertebral artery, and the esophagus, which X-ray cannot. If a leg is affected, the target is the lumbar sympathetic chain at the second through fourth lumbar vertebrae. This is done under live X-ray with contrast. The step-by-step technique, the visit, and recovery are on our complex regional pain syndrome treatment page. This page is about whether the diagnosis is right before any of that is booked.

These are real procedures with real risks, and you should hear them before a consent form. In the neck: Horner syndrome, hoarseness, trouble swallowing, a pocket of blood (hematoma), a seizure from accidental injection into the vertebral artery, and a collapsed lung. In the back: low blood pressure, short-term leg weakness or numbness, groin nerve pain, injury deep in the belly, bleeding, and infection. Blood thinners are reviewed before anything is booked.

What the evidence says about whether these blocks relieve pain. The 2023 Cochrane overview of systematic reviews by Ferraro and colleagues found no high-certainty evidence for the effectiveness of any therapy in this condition. It found moderate-certainty evidence that lidocaine sympathetic blocks probably do not reduce pain compared with placebo.² We do not dispute that finding here. In this practice, a sympathetic block is used as a diagnostic probe and as a window. During that window, a limb that could not stand touch can stand work. In our experience that window, when it opens at all, lasts from hours to a few weeks. That is something seen in practice, not a trial result, and individual results vary. If the window is not spent on graded motor imagery, mirror therapy, desensitization, and building load, it was wasted.

Hardware deserves the same scrutiny. Kemler and colleagues wrote in the Journal of Neurosurgery in 2008. It was the only randomized trial of spinal cord stimulation in CRPS type I, followed for five years.³ It enrolled a narrow group. All had severe CRPS type I of the hand or foot for six months or longer, not helped by standard care. So what it found applies to that group and no wider. At five years, stimulation plus physical therapy did about the same as physical therapy alone on pain relief and every other measure. And the effect faded over time. The trial was open-label with no sham comparison. And 10 of the 54 randomized patients were left out of the final analysis. A non-randomized subgroup of implanted patients did report a better overall sense of benefit (p=0.02). And 95 percent said they would do it again. But their pain relief did not reach statistical significance (p=0.06). That is the honest shape of the evidence. If you are being steered toward an implant without hearing it, get a second opinion. Hardware risks include lead movement, infection, a spinal fluid leak with headache, device failure, and repeat surgery. Rarely, a blood clot or abscess near the spinal cord causes lasting nerve injury. There are also permanent limits on future MRI.

On bisphosphonates, the Cochrane overview found low-certainty evidence that they may reduce pain after treatment. It also found moderate-certainty evidence that they probably raise side effects.² When metabolic health is poor, we work on blood sugar and nutrition. Tissue repair depends on them. But that is supportive care, not treatment for the syndrome. Photobiomodulation and specialized pro-resolving mediators are add-ons and unproven in this condition. They should be labeled exactly that way or not offered.

What recovery realistically looks like. The following is a composite — a picture built from many patients with this condition, not one person’s chart. An adult has routine foot surgery. It heals; the pain does not follow the healing. Four months later the foot is swollen, cold, purple when it hangs down, and cannot stand a sock. Two clinics have offered only more and more medicine. The Budapest criteria are met on exam. Blood vessel tests and electrodiagnostic studies (nerve tests) are ordered to rule out other causes, not to prove the diagnosis. A lumbar sympathetic block is done under live X-ray. The limb warms, and the relief lasts about ten days. Those ten days are the whole point, and they are hard. Desensitization is unpleasant before it is useful, and mirror therapy feels silly for two weeks. A second block, weeks later, gives less than the first. A cold snap in February undoes a month of progress. Nine months on, that patient walks a mile, wears a shoe, sleeps through the night, and drives again. That patient does not run, and the foot still tells the weather. That is a real result. It is not a cure, and no one should promise you one. Individual results vary.

Maybe your limb hurts far more than the injury explains, and it is swelling, sweating, or changing color and temperature. Do not accept vagueness. Ask for the Budapest criteria to be applied to you on paper. Ask how the other causes were ruled out. Ask what any proposed block is for, and what rehab is already on the calendar to fill the window it opens.

Frequently asked questions

Addresses, hours and directions are listed on our Locations page.

Key takeaways

• Complex regional pain syndrome is pain far out of proportion to the injury. It comes with changes in feeling, blood flow, sweating, and growth in the same limb. The four proposed mechanisms are frameworks, not tests. None can be measured in one patient.
• No scan or blood test confirms it. The diagnosis is made by exam with the Budapest criteria. They raised specificity from 0.41 under the older IASP criteria to 0.68. Imaging and nerve studies exist to rule out other causes.
• The evidence for treatment is truly limited. No therapy has high-certainty evidence, rehab included. There is moderate-certainty evidence that lidocaine sympathetic blocks probably do not beat placebo. And a five-year randomized trial looked at a narrow group with hard-to-treat type I. There, spinal cord stimulation was no better than physical therapy alone.
• Sympathetic blocks are best seen as a diagnostic probe and a rehab window. They are for patients who meet the criteria and are still limited despite active therapy. Graded motor imagery, mirror therapy, desensitization, and building load are the backbone of care.
• Insist on the diagnosis before the procedure, and on the rehabilitation before the hardware.

This article is educational and is not a substitute for evaluation, diagnosis, or treatment by a physician. Individual results vary. Do not start, stop, or change any medication without consulting your physician. To be evaluated, request an appointment at painmd.tv, call (314) 481-5000, or text (314) 886-5902.

References

1. Ferraro MC, Cashin AG, Wand BM, Smart KM, Berryman C, Marston L, Moseley GL, McAuley JH, O’Connell NE. Interventions for treating pain and disability in adults with complex regional pain syndrome: an overview of systematic reviews. Cochrane Database Syst Rev. 2023 Jun 12;6(6):CD009416. PMID 37306570. PubMed
2. Harden NR, Bruehl S, Perez RSGM, Birklein F, Marinus J, Maihofner C, Lubenow T, Buvanendran A, Mackey S, Graciosa J, Mogilevski M, Ramsden C, Chont M, Vatine JJ. Validation of proposed diagnostic criteria (the “Budapest Criteria”) for Complex Regional Pain Syndrome. Pain. 2010;150(2):268-274. PMID 20493633. PubMed
3. Kemler MA, de Vet HC, Barendse GA, van den Wildenberg FA, van Kleef M. Effect of spinal cord stimulation for chronic complex regional pain syndrome Type I: five-year final follow-up of patients in a randomized controlled trial. J Neurosurg. 2008;108(2):292-298. PMID 18240925. PubMed

Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP — Board Certified in Anesthesiology, Pain Medicine, Interventional Pain Management, Addiction Medicine, and Obesity Medicine. Last reviewed July 2026.

Dr. Gurpreet Singh Padda, MD, MBA, MHP