title: Sensor-driven position-adaptive spinal cord stimulation for chronic pain.
abstract: BACKGROUND
  Variation in the intensity of neurostimulation due to body position is a practical problem for many patients implanted with spinal cord stimulation (SCS) systems because positional changes may result in overstimulation or understimulation that leads to frequent need for compensatory manual programming adjustments.
  
  
  OBJECTIVE
  The purpose of this study was to assess the safety and effectiveness of a novel type of SCS therapy designed to automatically adapt stimulation amplitude in response to changes in a patient's position or activity.The primary objective of the study was to demonstrate that automatic position adaptive SCS benefited patients in terms of pain relief and/or convenience compared with neurostimulation adjusted with conventional manual programming. Secondary objectives included assessment of worsened pain relief with automatic adjustment; change in pain score; and the number of manual programming adjustments with position-adaptive neurostimulation compared with manual programming.
  
  
  METHODS
  Prospective, multicenter, open-label, randomized crossover study.
  
  
  METHODS
  Ten interventional pain management centers in the US.
  
  
  METHODS
  Patients were enrolled a minimum of one week after a successful SCS screening trial. They were then implanted with the RestoreSensor neurostimulation device (Medtronic, Inc., Minneapolis, MN) that could be programmed to either automatic position-adaptive stimulation (AdaptiveStim) or manual adjustment of stimulation parameters. After implant, all devices were programmed to conventional manual adjustment for a 4-week postoperative period. The patients were then randomized to either conventional manual programming adjustment or position-adaptive stimulation with crossover to the opposite treatment arm occurring at 6 weeks after randomization. The patients were followed for another 6 weeks after crossover. This study was conducted under an FDA-approved Investigational Device Exemption (IDE) and approval of the responsible Institutional Review Boards (IRBs) of the study centers.
  
  
  RESULTS
  Seventy-nine patients were enrolled in the study. In an intent-to-treat analysis, 86.5% of patients achieved the primary objective of improved pain relief with no loss of convenience or improved convenience with no loss of pain relief using automatic position-adaptive stimulation compared with using conventional manual programming adjustment alone. This was statistically significantly greater than the predefined minimum success rate of 25%, p < 0.001 (exact one-sided 97.5% lower confidence limit was 76.5%). Only 2.8% of patients reported worsened pain relief during position-adaptive stimulation compared with manual programming. There was a statistically significant reduction in the mean numeric pain rating scale score compared with baseline scores in both treatment arms. Additionally, position-adaptive stimulation demonstrated a statistically significant 41% reduction in the daily average number of programming button presses for amplitude adjustment compared with manual programming (18.2 per day versus 30.7 per day, P = 0.002). Functional improvements reported with position-adaptive stimulation included: improved comfort during position changes (80.3%); improved activity (69%); and improved sleep (47.9%). Adverse events associated with uncomfortable sensations from stimulation did not differ significantly between treatment arms. The incidence of device-related serious adverse events was 3.9%.
  
  
  CONCLUSIONS
  Patients and physicians were not blinded to whether devices were programmed to automatic position-adaptive stimulation or manual adjustment. Responses to assessment questionnaires were based on patient recall.
  
  
  CONCLUSIONS
  The study demonstrated that automatic position-adaptive stimulation is safe and effective in providing benefits in terms of patient-reported improved pain relief and convenience compared with using manual programming adjustment alone.
  
  
  BACKGROUND
  NCT01106404.
authors.affiliation: MAPS Applied Research Center, Edina, MN 55435, USA. dschultz@painphysicians.com
authors.forename: David M
authors.initials: DM
authors.lastname: Schultz
authors.forename: Lynn
authors.initials: L
authors.lastname: Webster
authors.forename: Peter
authors.initials: P
authors.lastname: Kosek
authors.forename: Urfan
authors.initials: U
authors.lastname: Dar
authors.forename: Ye
authors.initials: Y
authors.lastname: Tan
authors.forename: Mark
authors.initials: M
authors.lastname: Sun
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059350:Chronic Pain / Q000628:therapy; D018592:Cross-Over Studies; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D058542:Implantable Neurostimulators / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D059408:Pain Management / Q000379:methods*; D017060:Patient Satisfaction; D011183:Postoperative Complications / Q000517:prevention & control*; D011187:Posture; D011446:Prospective Studies; D013116:Spinal Cord / Q000601:surgery; D016896:Treatment Outcome