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Complex regional pain syndrome

Alternative names

Complex regional pain syndrome (CRPS) is a chronic pain syndrome with two forms. CRPS 1 currently replaces the term "reflex sympathetic dystrophy syndrome". It is a chronic nerve disorder that occurs most often in the arms or legs after a minor or major injury.

CRPS 1 is associated with severe pain; changes in the nails, bone, and skin; and an increased sensitivity to touch in the affected limb. CRPS 2 replaces the term causalgia, and results from an identified injury to the nerve.

Causes, incidence, and risk factors

CRPS often develops after an injury or infection that has occurred in an arm or leg. It can also occur after heart attacks and strokes. However, the condition can sometimes appear without obvious injury to the affected limb.

The cause of CRPS is not completely understood. It is thought to result from damage to the nervous system, including the nerves that control the blood vessels and sweat glands.

The damaged nerves are no longer able to properly control blood flow, sensation, and temperature to the affected area. This leads to medical problems in the nerves, blood vessels, skin, bones, and muscles.

This condition is more common in people between the ages of 40-60, but has been seen in younger people too.


In most cases CRPS has 3 stages. Often, however, CRPS does not follow this progression. Some people go into the later stages almost immediately. Others remain in Stage 1 indefinitely.

Stage 1 (lasts 1-3 months)

  • Severe burning, aching pain increasing with the slightest touch or breeze
  • Swelling with warmth or coolness
  • Skin becomes dry and thin, changes color
  • Increased nail and hair growth
  • Pain may move further up or down the affected limb

Stage 2 (lasts 3-6 months)

  • Swelling spreads
  • Noticeable changes in skin texture and color
  • Decreased hair growth
  • Changes in bone seen in X-rays
  • Stiff muscles and joints

Stage 3 (irreversible changes become evident)

  • Pain may exist in the entire limb
  • Permanent tissue changes
  • Muscle wasting
  • Limited mobility in limb
  • Contractions involving muscles and tendons

Signs and tests

Diagnosing CRPS can be difficult, but early diagnosis is very important. Often, the symptoms are severe compared to the original trauma or injury.

It is possible to make a diagnosis based on a medical history and physical examination. The key complaint is the severe, burning pain. Additional tests may include X-rays, bone scans, nerve conduction studies, and thermography (a test to show temperature changes and lack of blood supply in the painful area of the affected limb).


Usually, the recommended treatment will include a combination of therapies. These will include:

  • Medications -- pain medicines, steroids, blood pressure medicines that work on the sympathetic nervous system, bone loss medications (such as Actonel), and antidepressants
  • Physical or occupational therapy
  • Applications of heat and cold
  • The use of a TENS (trancutaneous electrical nerve stimulator) unit
  • Biofeedback
  • Nerve blocks (injecting medicine to numb the affected nerves or pain fibers around the spinal column)
  • Surgical sympathetomy (radical surgical that involves cutting the nerves to destroy the pain, but other sensations may be destroyed also)

Expectations (prognosis)

The outlook is better with an early diagnosis. If the condition is recognized within the first stage, sometimes it may go into remission and normal movement will be possible with minimal changes. However, if it is not diagnosed quickly, deteriorating changes in the bone and muscle may develop rapidly and become irreversible.


When the disease progresses, the complications include further deterioration of the affected limb, or the spread of the disease to another part of the body.

In addition, there are possible complications associated with some of the nerve and surgical treatments.

Calling your health care provider

You should contact your health care provider if you develop constant, burning pain in an arm, leg, hand, or foot.


There is no known prevention at this time, but early treatment is key to limiting the progression of the disease.

Update Date: 6/6/2002

Alan Greene, MD, CMO, A.D.A.M.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT