Patients with Reflex Sympathetic Dystrophy (RSD), re-named Complex Regional Pain Syndrome, type I (CRPS-I), have chronic, post-traumatic pain that spreads beyond the distribution of any single peripheral nerve without evidence of major peripheral nerve damage. A similar disorder, Causalgia, re-named CRPS-II, presents with clear evidence of nerve injury. No successful drug treatment exists for these disorders. Neurotropin is a non-protein extract of cutaneous tissue from rabbits inoculated with vaccinia virus. Neurotropin has been used extensively in Japan to treat RSD and other painful conditions; however, the drug has not undergone clinical therapeutic testing in the United States. This protocol is to carry out double-blind, placebo-controlled, crossover studies about clinical efficacy of Neurotropin for acute pain in dental outpatients and for chronic pain in outpatients with CRPS-I or II.