Complex regional pain syndrome (CRPS) refers to a chronic condition affecting the nerves and blood vessels of one or more extremities. It is distinguished by extremely unpleasant burning sensations, swelling, sweating, color changes, and other distressing symptoms.

There are two types of CRPS:

  • CRPS 1 (also called reflex sympathetic dystrophy or RSD)— No nerve damage exists with this type.
  • CRPS 2 (also called causalgia)—This produces similar symptoms after a nerve injury has occurred.

Complex Regional Pain Syndrome

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The cause of CRPS is not known. The condition likely results from several factors. It may involve overactivity of the sympathetic nervous system, which directs automatic body functions that a person cannot control. Inflammation also may play a role in the disorder.

Risk Factors

Minor or severe trauma increases the risk of CRPS:



If you have any of these symptoms do not assume it is due to CRPS. These symptoms may be caused by other conditions.

The upper extremities, particularly the hands, are most commonly affected. Symptoms progress and may vary during the course of the condition. Pain may spread from one side of the body to another. Many doctors describe symptoms in terms of stages.

Tell your doctor if you have any of these:

Within Hours or Days After Injury

Symptoms may include:

  • Deep aching or burning pain, typically more severe than expected from the injury
  • Sensitivity to touch or even a light breeze
  • Swelling in the arm or leg
  • Unusual sweating
  • Excessively warm or cool skin
  • Hair and nails changes

Symptoms may increase with stress and worsen over time.

3-6 Months After Injury

Symptoms may include :

  • Burning pain moves to above and below the initial injury
  • Swelling in the arm or leg hardens
  • Muscle spasms or weakness develop
  • Extremity becomes cold
  • Hair growth slows
  • Nails become brittle or crack

Six Months or Later After Injury

Symptoms may include :

  • A pale, blue, and/or shiny appearance to the skin
  • Limited joint movement
  • Muscle loss


Your doctor will ask about your symptoms and medical history and perform a physical exam. To diagnose CRPS, the doctor uses four criteria:

  • An initial traumatic or painful event to a limb, or immobilization of the limb for a period of time
  • Continuing pain in the limb that is out of proportion to any stimulus (eg, pain with even light touch)
  • History of swelling, changes in skin blood flow, or temperature only in the affected limb
  • No other cause for the symptoms

Tests may be ordered to rule out other conditions. Your doctor may refer you to a pain specialist for further evaluation and management. Tests may include the following:

  • X-ray]]> —a test that uses radiation to take a picture of structures inside the body, especially bones
  • ]]>Bone scan]]> —a special imaging test to check for early changes in bones
  • Thermogram—to measure heat radiating from the body, which may be diminished in CRPS extremity
  • Quantitative sudomotor axon reflex test (QSART)—a test that measures problems with the autonomic nervous system, like sweating
  • ]]>Nerve conduction studies]]> —test that measures the speed and degree of electrical activity in a nerve to determine if it is functioning normally
  • ]]>Electromyography]]> —measures and records the electrical activity that muscles generate at rest and in response to muscle contraction



Treatment aims to relieve pain and improve function. Visit the doctor as soon as possible. Early therapy may lead to better outcomes. In some cases, the condition goes away on its own; this is more common in children.

Treatment options include:

  • Biofeedback]]>
  • ]]>Acupuncture]]>
  • Physical therapy—Active and passive exercises help maintain function. Exercising in a warm pool may feel better than exercising on land.
  • Mirror box therapy—With this therapy, you place your affected hand or foot in a box, which has a mirror on one side. While moving your limb inside of the box, you move your unaffected limb in front of the mirror. To your brain, it appears that you are moving your painful limb easily and without discomfort. Mirror therapy may help to reduce pain and improve motor function in people who have CRPS due to stroke.
  • Transcutaneous nerve stimulation (TENS)—A device worn on the skin surface creates a tingling sensation and may relieve pain in some cases.
  • Medication
    • Anti-anxiety medications, low-dose antidepressants, and drugs used to treat ]]>epilepsy]]>
    • Pain medications, such as narcotics
    • Other drugs to control symptoms
  • Sympathetic nerve block—The injection of drugs that prevent the transmission of signals along sympathetic nerves may temporarily relieve pain in some cases.
  • Sympathectomy—If the nerve block is successful, a surgeon can permanently destroy sympathetic nerves. In some cases, surgery can worsen symptoms.
  • Psychological support— Long-term pain often leads to ]]>depression]]> or ]]>anxiety]]> . Counseling is often required to help patients deal with chronic pain and loss of function.



Quick mobilization after surgery or injury can help minimize the risk of CRPS in the affected extremity. Other steps that might be helpful include:

  • Early use of pain relievers after trauma
  • Use of sympathetic nerve block after trauma
  • Desensitization techniques (if needed)
  • Use of vitamin C]]> —In a study, this was shown to reduce the risk of CRPS after a wrist fracture. ]]>]]>