title: Evolving patterns of spinal cord stimulation in patients implanted for intractable low back and leg pain.
abstract: The objective of this study was to examine the programming strategies used in patients with intractable low-back pain treated with epidural spinal cord stimulation (SCS) utilizing paddle electrodes and a radio frequency (RF) stimulator. Programming strategies were examined in a group of patients implanted with a 16-contact paddle electrode and a dual channel RF receiver to treat chronic low-back pain. Baseline data included previous surgical history information, leg and low back pain severity and characteristics, and routine demographic information. Outcome measurements included the visual analog scale (VAS) (1), patient pain relief rating scale, and programming parameters. Patients rated their pain relief on a 5-point scale where 4 = excellent, 3 = good, 2 = fair, 1 = poor and 0 = none. Success was determined to be a pain relief score of "fair" or above. Data were collected during patient visits or by mail, at approximately 6, 12, and 24 months, postoperatively. Immediate postop data were available in 16 patients, 6-month data in 21 patients, 1-year data in 20 patients, and 2-year data in 10 patients, and analyzed for the purposes of examining programming strategies. The most common location for the tip of the electrode (lead) was found to be in the middle of the 8th thoracic vertebrae (N = 26). At the immediate postop assessment, the majority of cathodes were activated in the upper half of T9. By the 6-month follow-up, the majority of cathodes had shifted to the bottom of T9 and top of T10. Overall 88% of cathode locations were changed at one or more study visits. At 2 years, 86% of the programs used four or more active contacts. At 6 months, 83% of the patients reported that the therapy was a success, at 1 year, success was 94%, and by 2 years, success was 75%. Both SCS and chronic pain are dynamic processes. Complex pain patterns, such as the ones of patients who have pain in the low back and in one or both lower extremities, require a high degree of flexibility in the implanted SCS system. The system must provide the capability to redirect the current electronically over at least two segments of the spinal canal, to electronically steer the current in a medio-lateral direction, and to activate multiple electrical contacts simultaneously. The willingness and ability to provide extensive reprogramming in the long term follow-up is also of the utmost importance. Pain and its treatment with SCS is a dynamic process.
authors.affiliation: Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania and              Department of Bioengineering, University of Texas Southwestern Medical School, Dallas, Texas.
authors.forename: Ashwini
authors.initials: A
authors.lastname: Sharan
authors.forename: Tracy
authors.initials: T
authors.lastname: Cameron
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Barolat