Definition of Complex regional pain syndrome:

Complex regional pain syndrome (CRPS) is a chronic pain condition that can affect any area of the body, but often affects an arm or a leg.

Causes, incidence, and risk factors:

Doctors aren't sure what causes CRPS. In some cases, the sympathetic nervous system plays an important role in the pain. Another theory is that CRPS is caused by a triggering of the immune response, which leads to the inflammatory symptoms of redness, warmth, and swelling in the affected area.

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.

CRPS 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 directly to a nerve
• Injury or infection in an arm or leg

Rarely, sudden illnesses such as a heart attack or stroke can cause CSPS. 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.