What can you tell me about complex regional pain syndrome? Who gets it? How come? Is it connected with age at all?

Complex regional pain syndrome (CRPS) is a chronic (long lasting) painful condition, usually affecting the arm or leg. Patients with CRPS develop severe pain, swelling and changes in skin texture, hair growth, and temperature. Loss of motion accompanied by pain can lead to a loss of function and disability in daily activities, work, and recreation.

The International Association for the Study of Pain (IASP) has divided CRPS into two types based on the presence of nerve lesion following an injury. The injury could be as a result of surgery or bone fracture. Distal radial (wrist) fractures are the most common injury leading to CRPS, but no one knows why exactly. CRPS can also occur without any known trauma or injury. Non-traumatic cases of CRPS make up about 10 per cent of all affected patients.

Type I CRPS was formerly known as reflex sympathetic dystrophy (RSD), Sudeck's atrophy, or reflex neurovascular dystrophy (RND). There is no known or obvious nerve lesion in this type. Type II, formerly known as causalgia, occurs when there is obvious nerve damage.

Women are affected three times more often than men. Although it can occur at any age, adults between the ages of 50 and 70 years old seem to develop CRPS most often. One in three patients has symptoms in more than one limb. One in three patients develops dystonia, a movement disorder that contributes to even more dysfunction. The arm, wrist, and/or hand are affected slightly more often than the leg.

Although the exact cause remains largely unknown, it is suspected that there are multiple factors, possibly including genetic, nongenetic, and environmental contributions. Scientists from around the world are studying this problem in hopes of finding a way to treat it more effectively and perhaps even prevent it someday.