Effective Relief of Pain and Associated Symptoms With Closed-Loop Spinal Cord Stimulation System: Preliminary Results of the Avalon Study

Marc Russo; Michael J Cousins; Charles Brooker; Nathan Taylor; Tillman Boesel; Richard Sullivan; Lawrence Poree; Nastaran Hesam Shariati; Erin Hanson; John Parker

doi:10.1111/ner.12684

Effective Relief of Pain and Associated Symptoms With Closed-Loop Spinal Cord Stimulation System: Preliminary Results of the Avalon Study

Neuromodulation. 2018 Jan;21(1):38-47. doi: 10.1111/ner.12684. Epub 2017 Sep 18.

Authors

Marc Russo¹, Michael J Cousins², Charles Brooker^{3

4}, Nathan Taylor⁵, Tillman Boesel⁶, Richard Sullivan⁷, Lawrence Poree⁸, Nastaran Hesam Shariati⁹, Erin Hanson⁹, John Parker^{9

10}

Affiliations

¹ Hunter Pain Clinic, Broadmeadow, New South Wales, Australia.
² Pain Management Research Institute and Kolling Institute, University of Sydney at the Royal North Shore Hospital, St Leonards, NSW, Australia.
³ Department of Pain Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
⁴ Northern Clinical School, University of Sydney, Sydney, NSW, Australia.
⁵ Northern Private Pain Centre, St. Leonards, NSW, Australia.
⁶ Inner West Pain Center, Newtown, NSW, Australia.
⁷ Precision Brain, Spine, and Pain Centre, Kew, VIC, Australia.
⁸ University of California, San Francisco, CA, USA.
⁹ Saluda Medical Pty Ltd., Artarmon, NSW, Australia.
¹⁰ Graduate School of Biomedical Engineering, University of New South Wales, Kensington, NSW, Australia.

PMID: 28922517
DOI: 10.1111/ner.12684

Abstract

Objectives: Conventional spinal cord stimulation (SCS) delivers a fixed-input of energy into the dorsal column. Physiologic effects such as heartbeat, respiration, spinal cord movement, and history of stimulation can cause both the perceived intensity and recruitment of stimulation to increase or decrease, with clinical consequences. A new SCS system controls stimulation dose by measuring the recruitment of fibers in the dorsal column and by using the amplitude of the evoked compound action potentials (ECAPs) to maintain stimulation within an individualized therapeutic range. Safety and efficacy of this closed-loop system was evaluated through six-month postimplantation.

Materials and methods: Chronic pain subjects with back and/or leg pain who were successfully trialed received a permanent system (Evoke; Saluda Medical, Sydney, Australia). Ratings of pain (100-mm visual analogue scale [VAS] and Brief Pain Instrument [BPI]), quality of life (EuroQol instrument [EQ-5D-5L]), function (Oswestry Disability Index [ODI]), and sleep (Pittsburgh Sleep Quality Index [PSQI]) were collected at baseline and repeated three and six months after implantation.

Results: Fifty-one subjects underwent a trial procedure; permanent implants were placed in 36 subjects. The proportion of subjects with ≥50% relief was 92.6% (back) and 91.3% (leg) at three months, and 85.7% (back) and 82.6% (leg) at six months. The proportion with ≥80% pain relief was 70.4% (back) and 56.5% (leg) at three months, and 64.3% (back) and 60.9% (leg) at six months. Statistically significant improvements in mean BPI, EQ-5D-5L, ODI, and PSQI were also observed at both time points.

Conclusions: The majority of subjects experienced profound pain relief at three and six months, providing preliminary evidence for the effectiveness of the closed-loop SCS system. The exact mechanism of action for these outcomes is still being explored, although one likely hypothesis holds that ECAP feedback control may minimize recruitment of Aβ nociceptors and Aδ fibers during daily use of SCS.

Keywords: Evoked Compound Action Potential (ECAP); Spinal cord stimulation; back pain; closed loop; closed-loop; dose; feedback; feedback stimulation; leg pain; neuromodulation.

Publication types

Multicenter Study

MeSH terms

Adult
Aged
Australia
Chronic Pain / physiopathology*
Chronic Pain / therapy*
Feedback, Physiological
Female
Follow-Up Studies
Humans
Male
Middle Aged
Pain Measurement
Retrospective Studies
Spinal Cord Stimulation / methods*
Treatment Outcome*