Reflex Sympathetic Dystrophy (RSD), also called Complex regional pain syndrome (CRPS), is a chronic pain condition in which high levels of nerve impulses are sent to an affected site. Experts believe that RSD occurs as a result of dysfunction in the central or peripheral nervous systems.

RSD is most common in people aged 20-35. The syndrome also can occur in children; it affects women more often than men.

There is no cure for RSD.

What Causes RSD?
RSD most likely does not have a single cause but rather results from multiple causes that produce similar symptoms. Some theories suggest that pain receptors in the affected part of the body become responsive to catecholamines, a group of nervous system messengers. In cases of injury-related RSD, the syndrome may be caused by a triggering of the immune response which may lead to the inflammatory symptoms of redness, warmth, and swelling in the affected area. For this reason, it is believed that RSD may represent a disruption of the healing process.

What Are the Symptoms of RSD?
The symptoms of RSD vary in their severity and length. One symptom of RSD is continuous, intense pain that gets worse rather than better over time. If RSD occurs after an injury, it may seem out of proportion to the severity of the injury. Even in cases involving an injury only to a finger or toe, pain can spread to include the entire arm or leg. In some cases, pain can even travel to the opposite extremity.

Other symptoms of RSD include:

*”Burning” pain * Swelling and stiffness in affected joints * Motor disability, with decreased ability to move the affected body part * Changes in nail and hair growth patterns. There may be rapid hair growth or no hair growth. * Skin changes. RSD involves changes in skin temperature — skin on one extremity can feel warmer or cooler compared to the opposite extremity. Skin color changes also are apparent as the skin is often blotchy, pale, purple or red. The texture of skin also can change, becoming shiny and thin. People with syndrome may have skin that sometimes is excessively sweaty.

RSD may be heightened by emotional stress.

How Is RSD Diagnosed?
There is no specific diagnostic test for RSD, but some testing can rule out other conditions. Triple-phase bone scans can be used to identify changes in the bone and in blood circulation. Some health care providers may apply a stimulus (for example, heat, touch, cold) to determine whether there is pain in a specific area.

Making a firm diagnosis of RSD may be difficult early in the course of the disorder when symptoms are few or mild.

RSD is diagnosed primarily through observation of the following symptoms: * The presence of an initial injury * A higher-than-expected amount of pain from an injury * A change in appearance of an affected area * The presence of no other cause of pain or altered appearance.

How Is Complex Regional Pain Syndrome Treated?
Since there is no cure for CRPS, the goal of treatment is to relieve painful symptoms associated with the disorder. Therapies used include psychotherapy, physical therapy, and drug treatment, such as topical analgesics, narcotics, corticosteroids, antidepressants and anti-seizure drugs.

Other treatments include:

* Sympathetic nerve blocks: These blocks, which are done in a variety of ways, can provide significant pain relief for some people. One kind of block involves placing an anesthetic next to the spine to directly block the sympathetic nerves.

* Surgical sympathectomy: This controversial technique destroys the nerves involved in RSD. Some experts believe it has a favorable outcome, while others feel it makes RSD worse. The technique should be considered only for people whose pain is dramatically but temporarily relieved by selective sympathetic blocks. * Intrathecal drug pumps: Pumps and implanted catheters are used to send pain-relieving medication into the spinal fluid.

* Spinal cord stimulation: This technique, in which electrodes are placed next to the spinal cord, offers relief for many people with the condition.