Complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a form of chronic pain that usually affects an arm or a leg. complex regional pain syndrome (CRPS) typically develops after an injury, a surgery, a stroke or a heart attack. The pain is out of proportion to the severity of the initial injury.

CRPS is uncommon, and its cause isn't clearly understood. Treatment is most effective when started early. In such cases, improvement and even remission are possible.

Signs and symptoms of CRPS include:

• Continuous burning or throbbing pain, usually in the arm, leg, hand or foot
• Sensitivity to touch or cold
• Swelling of the painful area
• Changes in skin temperature — alternating between sweaty and cold
• Changes in skin color, ranging from white and blotchy to red or blue
• Changes in skin texture, which may become tender, thin or shiny in the affected area
• Changes in hair and nail growth
• Joint stiffness, swelling and damage
• Muscle spasms, tremors and weakness (atrophy)
• Decreased ability to move the affected body part

Symptoms may change over time and vary from person to person. Pain, swelling, redness, noticeable changes in temperature and hypersensitivity (particularly to cold and touch) usually occur first.

Over time, the affected limb can become cold and pale. It may undergo skin and nail changes as well as muscle spasms and tightening. Once these changes occur, the condition is often irreversible.

CRPS occasionally may spread from its source to elsewhere in the body, such as the opposite limb.

In some people, signs and symptoms of CRPS go away on their own. In others, signs and symptoms may persist for months to years. Treatment is likely to be most effective when started early in the course of the illness.

If you experience constant, severe pain that affects a limb and makes touching or moving that limb seem intolerable, see your health care provider to determine the cause. It's important to treat CRPS early.

The cause of CRPS isn't completely understood. It's thought to be caused by an injury to or difference in the peripheral and central nervous systems. CRPS typically occurs as a result of a trauma or an injury.

CRPS occurs in two types, with similar signs and symptoms, but different causes:

• Type 1. Also known as reflex sympathetic dystrophy (RSD), this type occurs after an illness or injury that didn't directly damage the nerves in the affected limb. About 90% of people with CRPS have type 1.
• Type 2. Once referred to as causalgia, this type has symptoms similar to those of type 1. But type 2 CRPS occurs after a distinct nerve injury.

Many cases of CRPS occur after a forceful trauma to an arm or a leg. This can include a crushing injury or a fracture.

Other major and minor traumas — such as surgery, heart attacks, infections and even sprained ankles — also can lead to CRPS.

It's not well understood why these injuries can trigger CRPS. Not everyone who has such an injury will go on to develop CRPS. It might be due to an interaction between your central and peripheral nervous systems that isn't typical and different inflammatory responses.

If CRPS isn't diagnosed and treated early, the disease may progress to more-disabling signs and symptoms.

• Tissue wasting (atrophy). The skin, bones and muscles may begin to deteriorate and weaken if you avoid or have trouble moving an arm or a leg because of pain or stiffness.
• Muscle tightening (contracture). You also may experience tightening of the muscles. This may lead to a condition in which the hand and fingers or the foot and toes contract into a fixed position.

These steps might help you reduce the risk of developing CRPS:

• Taking vitamin C after a wrist fracture. Studies have shown that people who take a high dose of vitamin C after a wrist fracture may have a lower risk of CRPS compared with those who didn't take vitamin C.
• Early mobilization after a stroke. Some research suggests that people who get out of bed and walk around soon after a stroke (early mobilization) reduce their risk of developing CRPS.