Quick Summary

• Complex Regional Pain Syndrome (CRPS), also known as Reflex Sympathetic Dystrophy (RSD) or Causalgia, is a chronic neurological condition caused by a malfunction or “short circuit” in the nervous system.

• The condition causes the brain to receive constant pain signals that are often far out of proportion to the original injury.

• Symptoms may include burning pain, temperature or color changes, swelling, hypersensitivity, stiffness, and changes in skin or nail appearance.

• Early diagnosis and treatment—such as physical therapy, desensitization, pain‑modulating medications, and nerve‑targeted therapies—can improve outcomes and reduce long‑term disability.

⚠️ Seek medical care promptly if pain becomes severe, persistent, or accompanied by dramatic temperature or color changes in the limb.

Complex Regional Pain Syndrome (CRPS)

Author: Dr. Marc Mitnick
Reviewed by: Medical Review Board





Reflex Sympathetic Dystrophy (RSD), Causalgia, Sudeck's Atrophy



WHAT IS COMPLEX REGIONAL PAIN SYNDROME



Complex Regional Pain Syndrome (CRPS) is a poorly understood neurological phenomenon that is even more confusing because it goes by so many different names. It is also known as Reflex Sympathetic Dystrophy (RSD), Sudecks Atrophy and causalgia.

The condition is basically a short circuit of the nervous system where nerves misfire thus sending constant pain signals to the brain even though there is no real or limited pain going on. In other words, it is a completely abnormal response by the nervous system to external stimuli.

CRPS can occur anywhere on the body but is fairly common in the foot and leg. Pain is out of proportion to an injury; the pain may be severe, constant or burning. There may be a hypersensitivity to external stimuli like heat or cold.

Three stages of complex regional pain syndrome

There are three stages in this condition, although most people do not necessarily have to go through all of the stages.

The Three Stages of CRPS


Stage 1: The Traumatic Stage

Timing: Starts immediately or several weeks after injury (including foot or leg surgery).

The skin becomes dry and red, transitioning to cool and moist within weeks. The foot and lower leg typically swell, joint movement becomes limited, and constant pain is present—often only alleviated by sleep or medication. In some cases, osteoporosis may begin here.

Stage 2: 2–6 Months Post-Injury

The skin becomes increasingly moist, tight, and shiny. Nails may become brittle and cracked. Patients often develop a guarded gait because the joints of the foot and ankle feel "locked."

Stage 3: 6–9 Months Post-Injury

This stage is characterized by irreversible structural changes, including soft tissue atrophy (wasting) and decalcification of the bone. Pain often worsens, becomes intractable, and may spread beyond the original site. The skin typically appears cool and dry.


Look at the picture of the feet below. Note the increased redness in the right foot. This patient had undergone surgery on the right foot, had been in a cast, and CRPS developed afterwards.

normal foot vs. crps foot






The following x-ray reveals the severe osteoporosis that can occur. Look how demineralized the middle of the foot appears.

crps damage xray






There are two types of CRPS, Type I and Type II. Type I is also referred to RSD and these involve cases in which the nerve injury cannot immediately be identified. Type II also referred to as Causalgia involves cases where there has been a major trauma to a distinct nerve.

TREATMENT FOR COMPLEX REGIONAL PAIN SYNDROME



There really is no laboratory test to diagnose Complex Regional Pain Syndrome. It is diagnosed on clinical grounds particularly to a nerve or soft tissue injury which does not respond in a normal healing path.

A thorough medical history and physical examination are necessary. It should be noted that in this instance surgery can be considered as an injury. CRPS has been seen quite frequently following elective foot surgery where the foot and lower leg required immobilization for a period of time due to the type of surgery performed.

It is estimated that people go to as many as five doctors before the proper diagnosis is made. The problem with this is that valuable time is wasted in beginning treatment. The earlier treatment is instituted , the better the prognosis.

There are basically three types of specialists that are the most likely to make a proper diagnosis and they should be consulted for treatment.

  • neurologist
  • physiatrist
  • anesthesiologist who specializes in pain management

Even going to one of these specialists does not guarantee proper diagnosis and treatment. You should ask your physician if he or she is experienced in treating this condition.

Treatment, of course, is based on the severity of the presenting symptoms. Treatment options includes:

  • Peripheral nerve blocks- may be performed in an effort to break up the ongoing pain sensation being transmitted to the brain.
  • A TENS unit- is sometimes of value in an effort to break the pain cycle.
  • Physical therapy- including massage, compression, and range of motion exercises to the affected areas.
  • nonsteroidal anti-inflammatory medication- may be used for pain and inflammation.
  • Systemic therapy with oral steroids, gabapentin, propranolol, nifedipine or other mood altering drugs may be helpful.
  • Surgical lumbar sympathectomy in very severe cases, may be performed as a means to break the pain cycle.

living with complex regional pain syndrome

The points to take away from this discussion of Complex Regional Pain Syndrome is that it is a diagnosis that is often overlooked and because of the delay in treatment, or even under treatment, permanent pain and disability may arise. Additionally there are only a few types of specialists that are properly experienced to adequately treat this condition.

Frequently Asked Questions


What is Complex Regional Pain Syndrome (CRPS)?
CRPS (formerly known as RSD or Causalgia) is a chronic neurological condition characterized by a "short circuit" in the nervous system. It causes the brain to receive constant, intense pain signals even when an injury is limited or healing.
What are the common symptoms of CRPS in the foot?
Symptoms often include severe burning pain, hypersensitivity to touch or temperature, swelling of the foot and leg, and changes in skin texture (becoming shiny or tight). In later stages, it can lead to muscle wasting and osteoporosis.
Can surgery cause CRPS?
Yes. Any trauma can trigger the condition. It is frequently seen following elective foot surgery, particularly when the limb has been immobilized in a cast for an extended period.
Is there a specific test to diagnose CRPS?
No. There is no specific laboratory test. Diagnosis is made on clinical grounds through a thorough medical history and physical examination by a specialist.
What specialists should I see for treatment?
You should consult a Neurologist, a Physiatrist, or an Anesthesiologist who specializes in pain management. Early diagnosis is critical for a better prognosis.

REFERENCES

Mayo Clinic

National Institute of Health

MedlinePlus

Questions I Have Answered From Visitors

Cold foot 3 weeks after surgery

Visitor name: Tina

Location: Torrance

Visitor's question

My husband had surgery 3 weeks ago on his ankle to remove two lesions from a previous injury. He also has an incision on the lateral portion of his foot from where they thought they would do a tendon and ligament repair, but after getting inside they felt it wasn’t necessary.

Surgery went great. The splint came off after 2 weeks and he is now non‑weight‑bearing with a boot, allowed to flex and extend the foot, which he does many times a day. Capillary refill is great, bruising is going down, and the incisions look great.

The only problem is that his foot remains cold as ice even with thick socks on. The skin is maybe a little pale, but not dramatically different from the other foot. Should we be concerned? If he has decreased circulation due to lack of movement, could this greatly affect healing?

Doctor's answer

Hi Tina,

Two possible conditions come to mind after reading your narrative. Keep in mind I am not making a diagnosis, as that is impossible from the other side of the internet.

The first possibility is Complex Regional Pain Syndrome (CRPS). This happens in individuals who have had foot surgery and generally end up in a boot or cast. It is essentially a short‑circuiting of the nerve transmission from the foot to the brain and the brain to the foot. You can read about it on my site. It can be difficult to diagnose, and the further along it goes, the more difficult it is to treat. If not diagnosed and treated, it can have debilitating effects.

The second possibility is an arterial embolism or a blood clot in one of the arteries that goes down the leg. I know nothing about your husband’s medical history or even his age, so I have no idea if he is at greater risk for this problem. If an artery is being blocked, then everything below the blockage will be colder and paler.

When one foot is noticeably colder and paler than the other, that is a sign of diminished circulation coming into the colder foot. That is not good and needs to be addressed immediately, regardless of the source.

I would call his surgeon immediately, and if for some reason you cannot get in touch with them, then I would suggest taking him to your local Emergency Room and having the foot checked out.

Marc Mitnick DPM


Fractured cuboid

by Stephanie
West Stewartstown, NH

I have a question on my cuboid fracture. I was seen by an orthopedic and he said I have a bone‑bruise type fracture on the cuboid bone. The problem I am having is more pain and swelling. My foot is a purple color. It has been six weeks. Now the pain is under the ball of my foot too, and radiates to the side of the foot. The pain gets worse and I cannot sleep at night.

The orthopedic told me to wear the walking boot only when I use my crutches and to elevate my leg. It has been getting worse. Can you tell me what you think I should do?

Hi Stephanie,

Obviously, without the luxury of being able to examine you, I cannot make a diagnosis as to why you are having more pain instead of less pain as time passes.

However, in cases like this where the pain is out of proportion to the injury and is getting worse rather than better as time passes, I am always concerned about the possibility of what is known as Complex Regional Pain Syndrome or CRPS. This is basically a condition where there is a short‑circuiting of the nerves in your foot and they are constantly “misfiring,” giving you the pain that you are experiencing.

Now, I am making certain assumptions here. One is that you have been wearing your walking cast for the whole period of time, as in many cases CRPS occurs primarily in women who have had their leg (or arm) immobilized for a prolonged period of time. I am also assuming that you are in good health and that both your arterial circulation (blood coming down to your foot) and venous circulation (blood going back to your heart) are normal. I am also assuming you have not been on your bad foot for prolonged periods of time and that you are not diabetic.

Your doctor may be entirely correct in his evaluation of why you have more pain and your foot is discolored, as he is actually able to examine you, but I think the prudent move would be to at least mention the possibility of CRPS to him.

Unfortunately, there are no tests that confirm whether a person is suffering from CRPS; rather, the diagnosis is made on clinical grounds. Furthermore, the diagnosis is usually made by a neurologist or even an anesthesiologist who specializes in pain management, as CRPS is routinely missed by many doctors.

I bother to even mention all this because on the chance that CRPS is what you are suffering from, if it is not properly diagnosed and aggressively treated, it can become a devastating problem — chronic pain that just worsens over time.

So, as I just stated, mention this to your doctor and let he or she decide if you should be worked up for this possibility. You can read more about it here.

Marc Mitnick DPM

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DISCLAIMER: The purpose of this site is purely informational in nature. It is not intended to diagnose, treat or cure any medical condition. This information is not a substitute for advice from a medical professional. Please consult your healthcare provider for accurate diagnosis and treatment. The information presented here may be subject to errors and omissions.


SITE LAST UPDATED: October 2026

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