RestoreSensor Study

The purpose of the study is to gather clinical information on subjects' experiences with and without the use of the new feature of the RestoreSensor implantable neurostimulator (INS).

This study is a multi-center, prospective, open-label, randomized, crossover study that is designed to gather clinical information on subjects' experiences with the use of the new feature of the RestoreSensor implantable neurostimulator. Current spinal cord stimulators for chronic intractable pain stimulate targeted nerves along the spine using electrical impulses. The stimulation interferes with the transmission of pain signals to the brain replacing painful sensations with a tingling sensation called paresthesia. Variation in the intensity of neurostimulation with body position is a challenge for some patients implanted with conventional spinal cord stimulation systems because positional changes may result in overstimulation or understimulation. Patients need to manually adjust their stimulation using the patient programmer to maintain their comfort level during position changes. The AdaptiveStim feature of the RestoreSensor neurostimulator was developed to address this challenge by improving pain relief and/or convenience relative to manual programming adjustments.

Adjustments to stimulation settings are automatic when the AdaptiveStim feature of the device is turned "ON" and manual when the AdaptiveStim feature of the device is turned "OFF".

Percentage of Subjects With Improved Pain Relief and/or Convenience During the AdaptiveStim Programming Arm Relative to the Manual Programming Arm

After subjects experienced both AdaptiveStim and manual programming at 16 weeks post-implant, subjects were asked to compare pain relief and convenience when they had AdaptiveStim ON to AdaptiveStim OFF in two separate domains using two 5-point Likert scales. The outcome measure for the primary objective is the percentage of subjects who report improved pain relief with no loss of convenience or improved convenience with no loss of pain relief during the AdaptiveStim programming arm relative to the manual programming arm. These subjects were considered successful for the primary objective.

Percentage of Subjects With Worsened Pain Relief When Using AdaptiveStim Compared to Manual Programming

The pain relief question was a 5-point Likert scale question comparing pain relief when using AdaptiveStim programming relative to manual programming after subjects finished both programming periods. The choices were much worse pain relief with AdaptiveStim, somewhat worse pain relief with AdaptiveStim, no difference in pain relief, somewhat better pain relief with AdaptiveStim, and much better pain relief with AdaptiveStim. Subjects who had worsening pain relief were defined as subjects who responded "much worse pain relief with AdaptiveStim" or "somewhat worse pain relief with AdaptiveStim".

The number of individual adjustments, ie, button presses, were recorded automatically in the patient programmer, which was specifically designed for this study. The number of button presses per day for manual patient programmer adjustments during the manual programming arm and the AdaptiveStim programming arm of the study were compared.

The 11-point (ie, 0-10) numeric rating scale of pain intensity (NPRS) was used to assess the overall pain at baseline and follow-up visits. In the pain diary, subjects were presented a numeric scale with numbers from 0 to 10, with 0 meaning "No pain" and 10 meaning "Pain as bad as you can imagine," accompanied by the instructions "Please rate your pain by indicating the number that best describes your pain on average in the last 24 hours." The subjects were asked to complete a diary for 7 consecutive days before implant, 10 weeks, and 16 weeks post-implant visits.

Inclusion Criteria: Meets the indications as an appropriate surgical candidate (after successful SCS screening trial) for implant of a neurostimulation system for spinal cord stimulation (SCS) treatment of trunk and/or limb pain, per labeled indications 18 years of age or older Willing and able to attend visits and comply with the study protocol Capable of using the patient programmer and recharging the neurostimulator (INS), able to read and answer questionnaires in English, without assistance of a caregiver Males and non-pregnant females Exclusion Criteria: Has had a prior implantable SCS neurostimulation system Currently enrolled, or plans to enroll in another investigational device or drug trial during the study Has unresolved legal issues related to their pain condition for which they would be receiving neurostimulation Requires cervical placement of leads.

Schultz DM, Webster L, Kosek P, Dar U, Tan Y, Sun M. Sensor-driven position-adaptive spinal cord stimulation for chronic pain. Pain Physician. 2012 Jan-Feb;15(1):1-12.