RSD is a rare disorder that affects the sympathetic nervous system. The sympathetic nervous system contains small nerves that control the size of blood vessels, the sweat glands, and other bodily processes. They are somewhat different from the larger nerves that go to your muscles and supply sensation to the skin. Exactly what happens to cause this disorder is not known in all cases. The inciting or causative event is always an injury (sometimes trivial) or surgery, major or minor, causing the sympathetic nerves to function in an abnormal way.
The result can be pain that is out of proportion to what would be expected from the injury or surgery. This pain usually occurs at or near the site of the injury or surgery, but can radiate away from the site, sometimes involving the whole limb. It is often described as an aching, burning pain that occurs with weight bearing or use, and also is bothersome at night. There is often hypersensitivity and swelling. Sometimes the skin is hot (or cold), bluish, reddish, or sweaty. These symptoms make it difficult to use the extremity and to rehabilitate it. Fortunately, very few patients have all the symptoms in their worst form. However, even in its minor forms, RSD can be frustrating and disabling.
The diagnosis of this condition can be made with the help of a triple-phase bone scan; this scan will be scheduled once the presumption of this diagnosis is made.
Once the diagnosis has been made, treatment is important. More minor cases may respond to continued use and rehabilitation of the extremity. Pain medications are of little or no value in the treatment of this disorder. If the symptoms are more than minor and/or do not respond to physical therapy, then more aggressive treatment is usually necessary. The most effective treatment is to temporarily block the function of the sympathetic nerves to the involved extremity (nerve block). That is done by injection of a local anesthetic into the back if the involved extremity is a leg, or the neck if the involved extremity is an arm.
A nerve block is performed by an anesthesiologist in the hospital, usually on an outpatient basis. Sometimes several blocks are necessary to get the disorder under control. In most cases, this treatment is effective and relieves symptoms enough to allow resumption of normal activities and rehabilitation, and then it eventually clears up. Relapses can occur, and cases that do not respond to outpatient treatment may require admission to the hospital, and further medical consultation.