(25) Extreme Pulse Dosing of 10 kHz Spinal Cord Stimulation

Introduction: An emerging concept is that reduced levels of spinal cord stimulation (SCS) may yield not only to shorter device recharge times, but also to longer term durability of pain control. To begin investigating this idea, we first explored 10kHz SCS with extreme pulse dosing (EPD): settings up to 50x lower than the smallest studied PD values. We hypothesized that patients would prefer EPD settings at a rate greater than previously published.

Methods: Patients already implanted with SENZA SCS implantable pulse generator (IPG) and using 10kHz SCS for chronic back and leg pain were enrolled. After taking Baseline measures, subjects underwent a waterfall-design ‘Dose Finding’ phase; they were first programmed with 3%PD setting they tried for 7-10 days. If subjects preferred to continue, they then tried progressively lower EPD settings (0.6%, 0.3%, 0.14%, 0.06%), each for 7-10 days, until they reached a EPD they didn’t prefer over the previous. Subjects then entered a 3 month Observational period in which they were to use their lowest EPD program. At the end of the Observational period, subjects returned to the clinic for their final visit. After each EPD tried, subjects completed questionnaires regarding pain intensity, satisfaction, patient global impression of change (PGIC), Oswestry Disability Index (ODI), Patient Catastrophizing Scale (PCS), Sleep Disturbance (PROMIS-SF), and adverse events. Device charging information was uploaded from the IPG at each visit. Data shown as [median;IQR].

Results: Eighteen patients were enrolled: 13M/5F, 61±12 years old. In the Dose Finding phase: 14/18 (78%) subjects preferred ≤ 3%PD, and 9/14 (64%) chose the smallest EPD settings (0.14%, 0.06%). All post-SCS pain scores were significantly less than the recall pre-SCS pain scores (p < 0.001) [9.0;2.0], and there was no significant difference between the Baseline pain score [3.0;3.5], the pain score at the subject’s chosen EPD (p=0.76); [3.0;3.0], and at the end of the Observational period (p=0.71) [4.0;4.5]. Similarly, satisfaction, PGIC, ODI, PCS, and PROMIS-SF scores for EPD were not statistically significantly different than those at Baseline. Daily device recharge requirements in minutes/day for EPD settings were reduced over ten-fold from Baseline [31.6;18.0] to [3.0;2.6].

Conclusion: This prospective feasibility study demonstrated that a larger majority of patients preferred profoundly low EPD programs than observed in previous studies, and a majority of these preferred programs which delivered stimulation for only seconds every hour with no significant change in clinical outcome measures. Longer-term evaluation of these subjects is underway to observe the durability of their outcomes.