Presented at the 2012 AAPM Annual Meeting « Back

Results of the RestoreSensor Study: Stimulation Amplitude Varies Significantly with Changes in Body Position

David M. Schultz, MD, dschultz@painphysicians.com¹, Lynn R. Webster, MD², Ye Tan, MS³, Dennis Skelton, BS³, Mark Sun, PhD³, Eric Panken, MS³, (1) MAPS Applied Research Center, Edina, Minnesota, (2) Lifetree Clinical Research, Salt Lake City, Utah, (3) Medtronic, Minneapolis, Minnesota

Introduction: Variations in paresthesia thresholds for different body positions have been theoretically estimated and measured acutely. We report on stimulation amplitudes associated with position changes during 6 weeks of position-adaptive stimulation. Materials and Methods: Patients received a RestoreSensor™ neurostimulation system (Medtronic, Inc., Minneapolis, MN) with optional position-adaptive stimulation capabilities as part of a prospective, multicenter, IRB-approved crossover study. Initially established amplitudes could be adjusted as needed during the 6-week position-adaptive stimulation arm of the study. Automated stimulation amplitudes for different positions were analyzed as a relative percent of the amplitude for the upright position at the end of the position-adaptive stimulation arm. Relative percentages from all the active programs were averaged for each position for each patient. Relative percentages for positions were tested against upright (100%) using a Wilcoxon signed-rank test. Results: Seventy-one patients (mean age 52.4 years, 58% female) completed the position-adaptive stimulation arm and were included in the analysis. The supine position had the lowest average stimulation amplitude relative to the upright position (mean 85%, SD 20%), while the mobile position had the highest average stimulation amplitude relative to the upright position (mean 107%, SD 19%) (Figure 1). The stimulation amplitudes for mobile, supine, lying right, and lying left were all significantly statistically different from those for upright (Wilcoxon signed-rank test, p-values < 0.05). Conclusions: Patients and/or physicians consistently programmed different stimulation amplitudes for different positions. The lowest stimulation amplitudes occurred in the supine position, and the highest amplitudes occurred in the upright position and during activity.

Funding: The RestoreSensor study was funded by Medtronic, Inc.