Reflex sympathetic dystrophy (RSD) is an older name for a condition now called Complex Regional Pain Syndrome (CRPS). It is a painful condition with features that include burning pain, tenderness to touch and sweating of an extremity. It is also associated with changes in the temperature of the skin as well as changes in the hair and nails. Although it can be suspected by your doctor, the diagnosis is best done by a board certified pain management physician such as an interventional anesthesiologist.
Reflex sympathetic dystrophy (RSD) is also known by the term “causalgia” which is a Greek term meaning “burning pain”. The term reflex sympathetic dystrophy was used to indicate that the cause was somehow related to the sympathetic nervous system. However, since the exact cause and mechanism of pain is unknown, a new way to describe it was needed. In 1993, a workshop was held in Orlando, Florida where it was decided to use the term Complex Regional Pain Syndrome (CRPS).
Although there are many names for CRPS including “shoulder-hand syndrome” and “Sudeck’s atrophy” the exact cause is unknown. The theories include irritation or abnormal excitation of nervous tissue, including the sympathetic nervous system. One mechanism is called ephaptic transmission and includes a short-circuit or cross-talk between nerve fibers. Wind-up or abnormal excitation in the spinal chord may also play a role.
There are a variety of events that can trigger CRPS. These include trauma, surgery, stroke, nerve damage or arthritis. Many times no inciting event is apparent. It can occur at any age. Women are more susceptible than men.
The symptoms of CRPS usually occur near the site of an injury. They usually spread proximally to involve the entire arm or leg. The most common symptom is a burning pain. There is localized swelling and increased sweating of the affected limb. The affected limb may be warmer to touch than the opposite side. The pain may increase with light touch or even emotional stress.
There may be three stages of CRPS. The acute stage occurs in the first three months. It includes burning, sweating and swelling as well as pain and tenderness of the extremity. The dystrophic stage occurs between three and six months. The skin becomes shiny and there are contractures. The pain persists but there may be less swelling and flushing of the skin. The third stage is atrophic and occurs greater than six months after the injury. There is loss of motion and function of the extremities with contractures. Osteoporosis and muscle wasting may occur.
The diagnosis of RSD and CRPS occurs mainly by history and physical exam. Usually there is: 1) the presence of an initial injury, 2) a higher than expected amount of pain after the injury, 3) a change in the appearance of the extremity and 4) the absence of any other cause of pain. Sometimes thermography can be useful in showing altered blood supply to the affected extremity. A doctor may order a “sweat test” to detect abnormal sweating. A triple phase bone scan may also be useful to support the diagnosis.
The treatment of reflex sympathetic dystrophy and complex regional pain syndrome is multi-disciplinary. Medication and physical therapy are often tried early and are the cornerstones of treatment. The medications may include anti-depressants, anti-inflammatories and vasodilators. GABA analogs such as gabapentin and pregabalin may be useful. Nerve blocks such as lumbar sympathetic blocks and stellate ganglion blocks are also useful, especially when performed early in the disease process. Surgical, chemical or radiofrequency sympathectomy can be used as a last resort. However, these procedures are not without risk. An interventional anesthesiologist is needed to determine whether or not to proceed with these procedures.