Chronic regional pain syndrome or reflex sympathetic dystrophy (RSD) might not be a single disorder but instead a class of disorders that have common features. The main cause of RSD is injury to the affected area, but it doesn’t have to be a serious injury. It can be from a minor motor vehicle accident, a crush injury or a minor laceration. The first RSD case handled by our offices more than 20 years ago occurred when our pedestrian client had her ankle struck by a deliveryman pushing a handcart at walking speed – an injury that at first appeared to have caused nothing worse than some bruising. What differentiates reflex sympathetic dystrophy from a normal injury is that the pain gets worse over time rather than better, and there are skin changes associated with the disease.
The precise pathophysiological cause of RSD, as noted above, is unknown. There may be several causes of the disease. While most cases have a precipitating event, up to one-third of all cases have no noted identifiable precipitating events. Theories around the causes of RSD include irritation of the nerves that cause excitation of the nervous tissue so that abnormal impulses spread along the nerves, affecting the blood vessels and skin. It appears to be related to the autonomic nervous system and, in particular, the sympathetic nervous system. Besides an injury, the following things can trigger a person to develop RSD:
- Having surgery
- Having heart disease
- Suffering from degenerative disease of the neck joints
- Having a stroke or other brain disease
- Having carpal tunnel syndrome or other nerve entrapment syndrome
- Developing shingles
- Having muscle or bony degenerative problems
- Having breast cancer
- Taking barbiturates
- Taking medication for tuberculosis
- Having fibromyalgia (in some cases)
Type 1 and Type 2 Causes
Type 1 disease was previously called “reflex sympathetic dystrophy syndrome”. It occurs following an injury or illness that doesn’t directly damage the involved nerves. About 90 percent of people who have what’s known as complex regional pain syndrome have type I disease.
Type 2 disease was once referred to as causalgia. This is caused by a distinct nerve injury that later causes the nerve to become inflamed. It can be due to blunt trauma to an extremity that leads to a crush injury. It also comes from amputations, sprained ankles, limb infections, surgery and other minor nerve-related injuries. Even emotional stress can contribute to getting RSD type II.
RSD doesn’t necessarily happen after a catastrophic injury. In general, the injuries are minor and one wouldn’t expect such serious consequences from such a minor injury. Just being in a cast for a long time after a fracture can trigger RSD. RSD may happen because the sympathetic nervous system becomes hyperactive and disturbed in some way. This may be why the patient experiences a burning pain, stiffness, discoloration and swelling of usually a hand/arm or foot/leg. Women get RSD more often than men but even children can develop the condition. In fact, this website has a page on RSD in children.
Sometimes RSD/CRPS may have very unexpected causes. For example, a recent study published in the Cleveland Clinic Journal of Medicine discussed a case in which CRPS resulted from injuries suffered in a dog bite. The victim’s doctors were initially mystified by the skin and temperature changes, and by the pain that was disproportionate to the relatively minor bite injury that had been suffered. They feared there was a serious infection, and the patient underwent treatment with multiple antibiotics. When new doctors were consulted, however, they suspected an autonomic nervous system disorder, and further testing confirmed their diagnosis of CRPS type 1, or RSD.