The second phase of the study will occur during the postoperative multi-day percutaneous SCS trial period. A hand-held trial stimulator typically used to deliver test stimulation during this trial period will be used to deliver stimulation for both standard care and the research study. A representative from St. Jude Medical (SJM) will work with each patient throughout the trial to program their system to its optimal setting, per the normal standard of care, but will not be involved in the collection of research data.