Complex regional pain syndrome (CRPS) is a chronic pain condition that mainly affects the arms and legs.

Complex regional pain syndrome (CRPS) has two forms:

• CRPS 1 is a chronic nerve disorder that occurs most often in the arms or legs after a minor injury.
• CRPS 2 is caused by an injury to the nerve.

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, feeling (sensation), and temperature to the affected area. This leads to medical problems in the:

• Blood vessels
• Bones
• Muscles
• Nerves
• Skin

Possible causes of CRPS:

• Injury or infection in an arm or leg
• Heart attack
• Stroke

The condition can sometimes appear without obvious injury to the affected limb.

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

In most cases CRPS has three stages. Often, however, CRPS does not follow this pattern. Some people go into the later stages almost right away. Others stay in the first stage.

Stage 1 (lasts 1-3 months):

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

Stage 2 (lasts 3-6 months):

• Decreased hair growth
• Noticeable changes in skin texture and color
• Spread of swelling
• Stiff muscles and joints

Stage 3 (irreversible changes can be seen)

• Contractions involving muscles and tendons
• Limited movement in limb
• Pain in the entire limb
• Muscle wasting

Depression or mood changes may occur with these symptoms, especially in stage 3.

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

The doctor will take a medical history and do a physical examination. Other tests may include:

• A test to show temperature changes and lack of blood supply in the affected limb (thermography)
• Bone scans
• Nerve conduction studies
• X-rays

Treatment should be started as early as possible. This may prevent the disease from getting worse. Treatment usually includes a combination of therapies, such as:

• Biofeedback
• Heat and cold
• Injected medicine that numbs the affected nerves or pain fibers around the spinal column (nerve block)
• Internal pain pump that directly delivers medications to the spinal cord
• Medications -- pain medicines, steroids, certain blood pressure medicines, bone loss medications (such as Actonel), and antidepressants
• Physical or occupational therapy
• Spinal cord stimulator
• Surgery that cuts the nerves to destroy the pain (surgical sympathectomy)

The outlook is better with an early diagnosis. If the doctor diagnoses the condition within the first stage, sometimes signs of the disease may disappear (remission) and normal movement is possible.

If the condition is not diagnosed quickly, changes to the bone and muscle may get worse and may not be reversible.

• Spread of the disease to another part of the body
• Worsening of the affected limb

Complications can also occur with some of the nerve and surgical treatments.

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. Early treatment is the key to slowing the progression of the disease.

Teadsdall RD, Smith BP, Koman AL. Complex regional pain syndrome (reflex synthetic dystrophy). Clinics in Sports Medicine. 2004;23:1.

Goetz CG. Goetz: Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders; 2007.