CHRONIC PAIN: REFLEX SYMPATHETIC DYSTROPHY SYNDROME

What Is Complex Regional Pain Syndrome?

Complex regional pain syndrome (CRPS) is a chronic condition characterized by severe burning pain, pathological changes in bone and skin, excessive sweating, tissue swelling and extreme sensitivity to touch. The syndrome is a nerve disorder that occurs at the site of an injury (most often to the arms or legs). It occurs especially after injuries from high-velocity impacts, such as those from bullets or shrapnel. However, it may occur without apparent injury.

One visible sign of CRPS near the site of injury is warm, shiny red skin that later becomes cool and bluish. The pain that patients report is out of proportion to the severity of the injury and gets worse, rather than better, over time. Eventually the joints become stiff from disuse, and the skin, muscles and bone atrophy.

The symptoms of CRPS vary in severity and duration. The cause of CRPS is unknown. The disorder is unique in that it simultaneously affects the nerves, skin, muscles, blood vessels and bones. CRPS can strike at any age but is more common between the ages of 40 and 60, although the number of CRPS cases among adolescents and young adults is increasing. CRPS is diagnosed primarily through observation of the symptoms. Some physicians use thermography to detect changes in body temperature that are common in CRPS. X-rays also may show changes in the bone.

Is There Any Treatment?

Physicians use a variety of drugs to treat CRPS. Elevation of the extremity and physical therapy also are used to treat CRPS. Injection of a local anesthetic is usually the first step in treatment. TENS (transcutaneous electrical stimulation), a procedure in which brief pulses of electricity are applied to nerve endings under the skin, has helped some patients in relieving chronic pain. In some cases, surgical or chemical sympathectomy — interruption of the affected portion of the sympathetic nervous system — is necessary to relieve pain. Surgical sympathectomy involves cutting the nerve or nerves, destroying the pain almost instantly, but surgery also may destroy other sensations as well.

What Is the Prognosis?

Good progress can be made in treating CRPS if treatment is begun early, ideally within three months of the first symptoms. Early treatment often results in remission. If treatment is delayed, however, the disorder can quickly spread to the entire limb, and changes in bone and muscle may07-Dec-2004 10:35 AM become irreversible. In 50 percent of CRPS cases, pain persists longer than six months and sometimes for years.

What Research Is Being Done?

Investigators are studying new approaches to treat CRPS and intervene more aggressively after traumatic injury to lower the patient's chances of developing the disorder. Scientists are studying how signals of the sympathetic nervous system cause pain in CRPS patients. Using a technique called microneurography, these investigators are able to record and measure neural activity in single nerve fibers of affected patients. By testing various hypotheses, these researchers hope to discover the unique mechanism that causes the spontaneous pain of CRPS, and that discovery may lead to new ways of blocking pain.

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