The normal clinical course of SCS for chronic pain includes a trial period of 3-30 days during which test stimulation is delivered via temporarily implanted epidural electrodes with an external percutaneous stimulation device. These electrodes are removed at the end of the trial period and, following a successful trial, a permanent set of electrodes and stimulation device are implanted at a later date. Subjects for this study will be recruited from patients planning to undergo percutaneous trial or paddle lead SCS implantation under the care of Dr. Nandan Lad at Duke University Medical Center.