CHRONIC PAIN: COMPLEX REGIONAL PAIN SYNDROME: OVERVIEW

Although complex regional pain syndrome (CRPS) was first described in Civil War veterans more than 140 years ago, it remains a poorly understood and sometimes undiagnosed disorder that may affect millions of people in the United States alone. It is a disorder that attacks both men and women, although the incidence is higher in women. The average age of CRPS patients is about 35, but the disorder can affect people of all ages. While the causes and symptoms range widely from one person to the next, the one over-riding symptom common to everyone with this disorder is severe pain that seems out of proportion to the injury or illness with which it is associated. In fact, pain is often the first indication that the disorder is present and is a primary reason for people with CRPS to seek medical advice and treatment. Another diagnostic element is disorder of the autonomic nervous system to the affected part. Over the years, CRPS has been known by a number of different names including Sudecks atrophy, post traumatic dystrophy and causalgia. Many people still use the popular term reflex sympathetic dystrophy (RSD) syndrome when discussing this disorder. However, in 1994, researchers and physicians from the International Association for the Study of Pain (IASP) reclassified the terms. These are:

· CRPS type-I, which used to be called RSD.

· CRPS type-II, which refers to people previously diagnosed as causalgia, who also have sustained nerve injuries.

The actual cause of this complex, often disabling syndrome is not known. While many people develop the syndrome in similar ways or experience common symptoms, there is no one explanation for the disease. Symptoms may come and go in the early stages and it is unknown whether some individuals are more susceptible to CRPS than others. A number of factors are linked to CRPS, but the leading culprit appears to be mild to severe trauma such as injuries or surgery. Something as simple as a sprain can lead to CRPS. Many people who sustain some type of injury may show signs of CRPS, while others become affected after surgery or after experiencing a painful event, such as a heart attack or an infection in an extremity such as an arm or leg. People with neurologic disorders, such as multiple sclerosis, also can develop CRPS, as can those with more chronically painful conditions such as carpal tunnel syndrome. A severe type of this disorder, CRPS type II, may develop when people injure a nerve or nerves in an extremity such as an arm, leg or foot. Examples of this type of injury are gunshot wounds and crush injuries. Nerve injuries often are characterized by numbness or tingling and/or sharp, shooting and aching pain in the skin supplied by the injured nerve. This kind of pain is described as "neuropathic" pain and can be confined to a small area of the body. CRPS is likely to be occurring when that pain spreads to other parts of the extremity and beyond and the autonomic nervous system becomes disordered. People with CRPS can experience a wide variety of symptoms besides pain and autonomic dysregulation, especially in the early stages of the disorder. These may include skin discoloration, muscle spasms, swelling and stiffness, feelings of heat or cold, dryness or excessive sweating in the involved area, excessive hair growth and excessive skin sensitivity to even the light touch of clothing (a symptom doctors call allodynia). There also can be extreme sensitivity to temperature and joint movement. In the later stages severe complications, such as persistent pain, muscle atrophy and a decrease in regional bone density, occasionally with fractures (osteopinia), may occur. According to the Reflex Sympathetic Dystrophy Syndrome Association of America (RSDSA), the future is looking brighter for people with CRPS due to promising research underway at institutions in the United States and throughout the world. This research involves studying the basic processes that cause the disorder as well as developing more effective treatments for CRPS.