Q. I have Reflex Sympathetic Dystrophy (RSD). I have found it very difficult to find any information about my condition. I have heard that it is a rare rheumatic disease. I have also heard that it is a form of neuropathic pain. Can you please explain what these mean? Also I have had RSD for three years now, and I have noticed that the pain has become more widespread in this time. Will the pain continue to spread and will it get worse?

A. This is a condition which has been known by several different names in the past. It was first described in a casualty of the American Civil War who suffered a bullet wound to the sciatic nerve. It was then called causalgia. There are several forms of this condition which is usually related to partial damage to a nerve. In this sense it is a neuropathic type of pain rather than rheumatic disease, which usually affects joints and soft tissues around them. The sympathetic nervous system comprises the nerves over which we have little control. These nerves go to the internal organs and along the main nerves to the skin and blood vessels. They cause our hands to go white in cold weather, due to contraction of these blood vessels, and conversely to flush in hot weather. They also affect the tiny muscles in the skin which change the appearance of the skin and cause goose pimples. It is thought that in some conditions where nerves have been damaged, there is an overactivity of these sympathetic nerves, which causes changes to the skin and temperature of the affected part and exaggerates the pain sensation carried by the damaged nerve which is usually described as burning or tingling.

Various forms of injection, surgery or drug treatment have been tried for this condition. These can be quite successful for some patients. Once nerve damage has been present for some time it is unlikely to ever recover and the best treatment one can expect is to reduce the symptoms. The condition is unlikely to spread significantly but as with all chronic pain states, there is sometimes a hypersensitivity of the adjacent nerves which lowers the pain threshold around the affected area and seems to cause spreading of the pain.