If treatment is delayed, however, the disorder can quickly spread to the entire limb and changes in bone and muscle may become irreversible. In 50 percent of RSDS cases, pain persists longer than 6 months and sometimes for years. Injection of a local anesthetic, such as lidocaine, is usually the first step in treatment. Injections are repeated as needed. In some cases, surgical or chemical sympathectomy interruption of the affected portion of the sympathetic nervous system is necessary to relieve pain.
Surgical sympathectomy involves cutting the nerve or nerves, destroying the pain almost instantly.
But surgery may also destroy other sensations as well. RSDS has many of the same features as causalgia, such as severe burning pain that is aggravated by physical or emotional stimuli. Investigators are studying new approaches to treat RSDS and intervene more aggressively after traumatic injury to lower the patient's chances of developing the disorder. Using a technique called microneurography, these investigators are able to record and measure neural activity in single nerve fibers of affected patients. By testing various hypotheses, these researchers hope to discover the unique mechanism that causes the spontaneous pain of RSDS and that discovery may lead to new ways of blocking pain.