Sensor-Driven Position-Adaptive Spinal Cord
Stimulation for Chronic Pain
Authors: Schultz David 
Published: March 2021

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.
Objectives: 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.
Study Design: Prospective, multicenter, open-label, randomized crossover study.
Setting: 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 RestoreSensorTM neurostimulation device (Medtronic, Inc., Minneapolis, MN) that could
be programmed to either automatic position-adaptive stimulation (AdaptiveStimTM) 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%.
Limitations: 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.
Key words: spinal cord stimulation, neurostimulation, position sensing, physical activity accelerometer,
neuromodulation, effectiveness, pain relief, position-adaptive stimulation, posture-adaptive stimulation, AdaptiveStim
Clinical Trial: NCT01106404