Brief Summary: This is a multi-center, prospective, open-label, single-arm, observational, feasibility study. The goal of this study is to determine the feasibility of intra-spinal stimulation with optimal paresthesia coverage therapy for chronic pain relief in patients with complex regional pain syndrome type I or causalgia. Up to 20 patients with intractable chronic severe limb pain associated with complex regional pain syndrome (CRPS) will be included in the study. A standard of care trial phase to test a subjects' response to Intraspinal-Optimal Stim therapy will be conducted during a 3 to 10-day period. Patients that obtain 50% or greater pain relief during the trial period will undergo permanent implantation of the device. Primary outcome will evaluate pain response at 3 months of therapy, based on NPRS pain score relative to baseline. Patients will be followed up for 6 months after the start of therapy.