Measuring Evoked Potentials From the Spinal Cord and Dorsal Root Ganglion

Inclusion Criteria: * Subject is at least 18 years of age. * Subject is able and willing to comply with the schedule and protocol. For implantation of DRG stimulator; * Subject has been diagnosed with complex regional pain syndrome (CRPS I or II). * Subject has had chronic, intractable pain of the groin or lower limbs for at least 6 months. * Subject is indicated for implantation of an Abbott DRG stimulation system. * Subject will be undergoing trial implantation of an Abbott DRG stimulation system. For implantation of SCS; * Subject has been diagnosed with chronic, intractable pain of the trunk and/or limbs. * Subject is indicated for implantation of a SCS system. * Subject will be undergoing implantation of an Abbott lead. * Subject has had stable neurologic function in the past 30 days. * Subject is able to provide informed consent. Exclusion Criteria: * Subject will be implanted with 3 or more DRG leads. * Subject is currently participating in a clinical investigation that includes an active treatment arm. * Subject has exhibited escalating or changing pain condition within the past 30 days as evidenced by physician examination. * Subject currently has an active implantable device including an ICD, pacemaker, spinal cord stimulator, or intrathecal drug pump. * Subject is a prisoner. * Female subject is pregnant.