Complex Regional Pain Syndrome is a debilitating and extremely difficult to treat condition. There is a large body of evidence demonstrating the therapeutic value of N-methyl-D-aspartate (NMDA)-receptor antagonists in CRPS. The NMDA antagonist ketamine has been shown to be effective in the treatment of CRPS, resulting in complete remission of the disease in some patients. The purpose of this study is to evaluate intravenous outpatient infusion of sub-anesthetic doses of ketamine for the treatment of CRPS. A thorough evaluation of this procedure, providing information into the degree of relief and which of the constellation of RSD symptoms are best alleviated by this procedure would result in the optimization of this therapy for the treatment of CRPS.