title: Spinal cord stimulation with interleaved pulses: a randomized, controlled trial.
abstract: Objectives.  The development of multicontact electrodes and programmable, implanted pulse generators has increased the therapeutic success of spinal cord stimulation (SCS) by enhancing the ability to capture and maintain pain/paresthesia overlap. This study sought to determine if interleaved stimulation and/or frequency doubling improves pain/paresthesia overlap in patients with failed back surgery syndrome. Methods.  Using a patient-interactive computer system that quantifies SCS performance and presents stimulation settings in randomized, double-blind fashion, we compared the effect on pain/paresthesia overlap of interleaved stimulation (rapidly interleaved pulse trains using two different contact combinations) vs. standard treatment with a single contact combination, controlling for frequency doubling. Stimulation amplitude (charge per phase, as determined by varying pulse voltage or width) was adjusted to a subjectively comfortable intensity (usage amplitude), which was maintained for all trials in each patient. The number of percutaneous spinal electrodes used (one or two) and the phase angle between interleaved pulses were additional study variables. Results.  Multivariate analysis of 266 test results from 15 patients revealed a statistically significant (p ≤ 0.05) association between increased computer-calculated pain/paresthesia overlap and 1) high- and low-frequency interleaved stimulation using two combinations of contacts and 2) frequency doubling using one combination. We found no significant effect for electrode configuration (single or dual), pulse width matching, or phase angle. Conclusions.  The statistically significant advantages we observed for SCS with interleaved stimulation are explained, at least in part, by the effects of frequency doubling. These findings have important implications for the design and adjustment of pulse generators.
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD; and              Department of Population and Family Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: North
authors.forename: David H
authors.initials: DH
authors.lastname: Kidd
authors.forename: John
authors.initials: J
authors.lastname: Olin
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Sieracki
authors.forename: Marc
authors.initials: M
authors.lastname: Boulay