Complex regional pain syndrome (CRPS), still widely called reflex sympathetic dystrophy or RSD, is traditionally described in three stages. They are an acute inflammatory stage, a dystrophic stage, and an atrophic stage. The stage labels are handy shorthand for what a limb can look like. But they are not a timeline. The largest studies that looked for three phases in a row did not find them. And how long a person has had CRPS does not predict which “stage” they resemble.12
This page explains what the three stages describe and why staging in sequence was dropped. It also covers what clinicians use in its place: the Budapest diagnostic criteria, and a simpler description of the limb as warm or cold.
What are the stages of CRPS?
The three-stage model dates to clinical write-ups made long before anyone knew the mechanism behind the condition. It grouped findings that tend to show up together. The time ranges tied to each stage differ from one account to the next. No prospective study (one that follows patients forward in time) has tracked patients through them in order.1 Treat the ranges below as the way the model is taught, not as a schedule any one person follows.
Stage 1 — the acute or “warm” picture
Burning or aching pain out of proportion to the original injury. Swelling. A limb that is warmer and redder than the other side. More sweating, and faster nail and hair growth. Pain set off by light touch (allodynia) or by normally mild pressure (hyperalgesia). Usually described as roughly the first one to three months.
Stage 2 — the dystrophic picture
Swelling becomes firmer. The skin may turn cool and mottled or bluish. Nails thicken and become brittle, hair growth slows, and joints stiffen. Muscle around the joint weakens. Bone density on the affected side may fall. Usually described as roughly months three to nine.
Stage 3 — the atrophic picture
The limb is cool, pale or glossy. The skin and the tissue under it thin out. Contractures (tightened tissue that locks a joint) limit motion, and function is lost. Pain may spread beyond the original area. Usually described as beyond a year.
Does CRPS always progress through the stages in order?
Two studies are usually cited against the staging model, and both used large groups of patients.
A prospective Dutch study of 829 patients with reflex sympathetic dystrophy examined signs and symptoms directly. It reported that it found no evidence consistent with three phases of the disease in a row. It also found that the early picture is dominated by regional inflammation, not by an overactive sympathetic nervous system. Hyperhidrosis (heavy sweating), the classic “sympathetic” sign, was too rare to have any diagnostic value. Pain was present in 93 percent, hyperpathy (an exaggerated painful reaction to a touch or other stimulus) in 75 percent, and reduced sensation in 69 percent.1
A second study took 113 patients who met the older International Association for the Study of Pain criteria. A clustering algorithm sorted them by their real pattern of signs and symptoms across four domains. Those were pain and sensory change, vasomotor change (blood flow and skin color), swelling and sweating, and motor and trophic change (movement, skin, hair and nail changes). Three statistically distinct groups emerged. But they did not differ in any meaningful way in how long the patients had been in pain. A staging model predicts that they should differ. The group that looked most like “classic RSD,” with the heaviest motor and trophic findings, had directionally the shortest pain duration of the three.2
So the clusters are real. The ordering is not. A person can arrive with a cold, stiff, atrophic-looking (wasted) limb at four months, or with a hot swollen limb at three years.
How is CRPS diagnosed and described today?
Warm CRPS and cold CRPS
The split that has held up better is temperature. Reviews of the mechanisms describe a shift from “warm” CRPS to “cold” CRPS. In warm CRPS, inflammation in the limb dominates. In cold CRPS, other things matter more: central sensitization (an oversensitive nervous system), changed sympathetic and catecholaminergic (adrenaline-type) signaling, and rewired body maps in the brain. How much each mechanism adds differs between patients, and within the same patient over time.3 This describes which mechanism is loudest right now. It is not a stage a patient graduates from.
The Budapest criteria
CRPS has no blood test or scan that confirms it. It is diagnosed clinically, using the Budapest criteria. All four parts must be met. Pain continues and is out of proportion to the event that started it. The patient reports at least one symptom in three of the four domains (sensory, vasomotor, sudomotor/edema, motor/trophic). The examiner sees at least one sign in two of those domains at the visit. And no other diagnosis better explains the findings.4
The validation study compared these criteria against the older IASP criteria in 113 CRPS-I patients and 47 patients with other neuropathic (nerve) pain. The old criteria were almost perfectly sensitive (1.00) but specific only 0.41. In other words, they labeled a large share of non-CRPS patients as CRPS. The Budapest clinical criteria kept sensitivity at 0.99 and raised specificity to 0.68. The stricter research version reached 0.79.4 A later systematic review looked at every screening and diagnostic tool proposed for CRPS. It concluded that for adults the Budapest criteria are the preferred tool. It also found that no validated screening tool exists at all.5 A fuller walkthrough is on our Budapest criteria page.
Specificity matters here because the old criteria made the problem look bigger than it is. One prospective study screened 306 patients in a row with foot and ankle fractures using the Budapest criteria. Of them, 110 reported at least one CRPS symptom. But only one met the full mix of symptoms and signs. That is an incidence of 0.3 percent.6
Is CRPS type 2 worse than type 1?
Type 1 (historically RSD) follows an injury with no nerve lesion that can be found. Type 2 (historically causalgia) follows a documented nerve injury. The symptoms and the treatment approach are largely the same. The difference is whether a specific nerve lesion can be shown, which is where electrodiagnostic testing is useful. In the clustering study above, one subgroup was dominated by nerve pain and sensory changes. Its EMG and nerve conduction findings suggested type 2.2 Type is not a severity grade. It is a statement about whether a nerve lesion was found.
How long does CRPS last?
A systematic review of 18 studies covering 3,991 patients found the honest answer is split. The three prospective studies showed that for many patients symptoms improve markedly within six to thirteen months of onset. The retrospective studies (ones that looked back at past records) varied far more. They documented lasting impairment in many patients. Across studies, sweating and vasomotor findings were the most likely to resolve. Motor findings, stiffness and weakness, were the most likely to persist. The review’s authors noted that little is known about which patients fall into which group. They rated the overall quality of the evidence as poor.7
For scale: a population-based study drew on 600,000 Dutch primary-care records. It estimated an overall incidence of 26.2 CRPS cases per 100,000 person-years (95% CI 23.0–29.7). Women were affected at least three times as often as men, with a peak in women aged 61–70. The arm was hit more often than the leg, and a fracture was the starting event in 44 percent of cases. Read that number with care. Its authors point out that it is more than four times higher than the only other population-based estimate then available, from Olmsted County in the United States. They report that gap rather than resolve it. It is a reminder that how often CRPS is counted depends heavily on how it is defined.8
Does the stage change the treatment?
Not in the way the model implies. There is no evidence-based protocol tied to a stage number. Current practice guidelines are built around restoring function early, through active movement, desensitization, and graded loading. Interventional and drug treatments are used to make that movement bearable, not as ends in themselves. The 5th edition guidelines are candid that most of the research behind them is low to medium quality, with small samples. Part of the reason is that CRPS is uncommon. Another part is that the diagnostic category is so broad that a treatment that works in one subset can be diluted to non-significance across a whole trial.9
That caveat applies to specific treatments too. A double-blind randomized trial gave a 4.2-day intravenous ketamine infusion to 60 CRPS-1 patients with long-standing severe pain. It found significantly lower pain scores than placebo across a 12-week window. The largest gap came at week 1, and no statistically significant difference remained by week 12. There was also no measurable gain in function. Psychomimetic side effects (mind-altering effects) occurred in 76 percent of the ketamine group versus 18 percent on placebo.10 That is a real effect worth knowing about, and also a limited one. We describe the evidence by route on our ketamine therapy page.
Here is what dropping the staging model means in practice. Nothing about a cool, stiff limb means the window has closed. Nothing about a warm swollen limb means it will surely get worse. What guides treatment is the person’s findings on examination, not a stage number.
If you are in the St. Louis area
Padda Institute evaluates and treats CRPS and RSD at 4477 Woodson Rd, Suite 100, St. Louis, MO 63134, and at 12174 Natural Bridge Rd, St. Louis, MO 63044. Dr. Gurpreet Singh Padda, MD, MBA, MHP performs the Budapest-criteria examination. He builds a plan around restoring use of the limb. Details are on the CRPS treatment page, or call (314) 481-5000.
Frequently asked questions
How many stages of CRPS are there?
Three are traditionally described: acute, dystrophic, and atrophic. But studies that tested whether patients pass through them in order did not find a fixed sequence. The stages are best read as pictures a limb can show, not steps. Diagnosis rests on the examination instead, as described on our Budapest criteria page.
Is CRPS stage 3 permanent?
An atrophic-looking limb is not by itself proof of a condition that cannot be reversed. It also does not tell you how long the condition has been present. Motor findings such as stiffness and weakness are the ones most likely to persist. That is why treatment pushes movement early. Our page on whether CRPS can be cured covers what is and is not known about long-term outcomes.
What is the difference between CRPS type 1 and type 2?
Type 1 follows an injury without a nerve lesion that can be shown. Type 2 follows a documented nerve injury. Both are diagnosed by the same clinical criteria. Whether a nerve lesion is present is checked with nerve conduction and EMG studies. See what EMG and nerve conduction studies measure.
Is CRPS the same thing as RSD?
Largely, yes. Reflex sympathetic dystrophy was the older name for what is now called CRPS type 1. Much of the core research, including the 829-patient study that undercut the staging model, was published under the RSD label. Many clinicians, including ours, still use both terms. Our CRPS and RSD page uses them interchangeably.
Do sympathetic nerve blocks work for CRPS?
They help some patients and not others. The response is used to diagnose as well as to treat. For an arm, that is usually a stellate ganglion block; for a leg, a lumbar sympathetic block. Whether and how often to repeat one depends on what the first one showed, not on a fixed schedule.
Does waiting make CRPS harder to treat?
The evidence on timing is weaker than the confident advice you will read online. But the findings most likely to persist are the motor ones: stiffness, weakness, and lost range. Those are the ones that respond to early, steady use of the limb. We discuss the real-world effects on our page about the cost of delayed CRPS treatment.
What is the most painful stage of CRPS?
No stage is reliably the most painful. The classic model pairs stage 1 with burning pain out of proportion to the injury, and stage 3 with pain that may spread. But patients do not move through those stages in order. Time since onset does not predict which picture a limb shows. In the 829-patient Dutch study, pain was present in 93 percent of patients. What guides care is your examination, not a stage number.
How quickly does CRPS progress?
There is no fixed speed. The model teaches roughly one to three months for stage 1, three to nine months for stage 2 and beyond a year for stage 3. But no prospective study has followed patients through those steps in order. One person can have a cold, stiff limb at four months. Another can have a hot, swollen limb at three years. For many people, symptoms improve markedly within six to thirteen months of onset.
How common is CRPS?
It is uncommon, and the count depends on how it is defined. A Dutch study of 600,000 primary-care records estimated 26.2 cases per 100,000 person-years. Women were affected at least three times as often as men, and a fracture started 44 percent of cases. The stricter Budapest criteria find far fewer. Among 306 patients with foot and ankle fractures, only one met the full criteria.
Sources
- Veldman PH, Reynen HM, Arntz IE, Goris RJ. Signs and symptoms of reflex sympathetic dystrophy: prospective study of 829 patients. Lancet. 1993. PMID 8105263
- Bruehl S, Harden RN, Galer BS, Saltz S, Backonja M, Stanton-Hicks M. Complex regional pain syndrome: are there distinct subtypes and sequential stages of the syndrome? Pain. 2002. PMID 11790474
- Bruehl S. An update on the pathophysiology of complex regional pain syndrome. Anesthesiology. 2010. PMID 20693883
- Harden RN, Bruehl S, Perez RSGM, et al. Validation of proposed diagnostic criteria (the “Budapest Criteria”) for Complex Regional Pain Syndrome. Pain. 2010. PMID 20493633
- Mesaroli G, Hundert A, Birnie KA, Campbell F, Stinson J. Screening and diagnostic tools for complex regional pain syndrome: a systematic review. Pain. 2021. PMID 33230004
- Bullen M, Lang C, Tran P. Incidence of Complex Regional Pain Syndrome I following foot and ankle fractures using the Budapest criteria. Pain Medicine. 2016. PMID 28025369
- Bean DJ, Johnson MH, Kydd RR. The outcome of complex regional pain syndrome type 1: a systematic review. The Journal of Pain. 2014. PMID 24530407
- de Mos M, de Bruijn AGJ, Huygen FJPM, Dieleman JP, Stricker BHCh, Sturkenboom MCJM. The incidence of complex regional pain syndrome: a population-based study. Pain. 2007. PMID 17084977
- Harden RN, McCabe CS, Goebel A, et al. Complex Regional Pain Syndrome: Practical Diagnostic and Treatment Guidelines, 5th Edition. Pain Medicine. 2022. PMID 35687369
- Sigtermans MJ, van Hilten JJ, Bauer MCR, et al. Ketamine produces effective and long-term pain relief in patients with Complex Regional Pain Syndrome Type 1. Pain. 2009. PMID 19604642
Dr. Gurpreet Singh Padda, MD, MBA, MHP
