Background & Aims

Mechanical nociceptive chronic low back pain (CLBP) can be caused by impaired neuromuscular control of lumbar spine stability. Underlying this lack of stability lies dysfunction of the multifidus, the strongest stabilizer of the lumbar spine.1 The ReActiv8-B randomized sham-controlled pivotal trial (clinicaltrials.gov identifier: NCT02577354) utilized an implantable restorative neurostimulation system which bilaterally stimulated the medial branches of the L2 dorsal rami for up to 30 minutes twice daily to override underlying lumbar multifidus muscle inhibition and facilitate neuromuscular control restoration. The ReActiv8-B trial provided evidence of safety, effectiveness, and durability of this therapy over five years.2,3 Few if any prospective neuromodulation trials have shared efficacy, safety, and participant accountability outcomes beyond two years.

Methods

Eligible patients had activity-limiting mechanical CLBP (visual analog scale (VAS) ?6cm; Oswestry Disability Index (ODI) ?21 points) despite medical management, which included at least pain medications and physical therapy. Participants also had evidence of impaired multifidus motor control (positive prone instability test) and no indications for spine surgery. Following institutional review board approval, all consented patients were implanted with a restorative neurostimulation system (ReActiv8, Mainstay Medical, Inc., Ireland).

Results

Participants (N=204) at baseline were age 47±9 years, had CLBP for 14±11 years, rated low back pain VAS at 7.3±0.7 cm, ODI at 39±10, quality of life (measured by Euroqol EQ-5D) at 0.585±0.174 points, and had pain on 97±8% of days in the year prior to enrollment. Out of 204, 100% had failed medications with 37% on opioids at baseline. At 5-year follow-up, 126 complete cases presented with an improved average VAS by 4.9±2.5 cm (67.5±3.1% improvement), ODI by 22.6±15.4 (22.7±1.4% improvement), and EQ-5D by 0.230±0.203 (P<0.0001 for all outcomes); 71.8% of participants had ?50% VAS improvement; 66.9% reported LBP resolution (VAS?2.5 cm); 61.1% had ?20-point ODI improvement and 88% of participants were “definitely satisfied” with treatment. Pain intensity and disability are interdependent symptoms, therefore, treatment success was determined by composite improvements in ODI and VAS: 78.2% had substantial improvements of ?50% in VAS and/or ?20 points in ODI. Of participants using opioids.

Conclusions

Over a follow-up duration of five years, restorative neurostimulation has proven effective, durable, and safe. In patients severely affected by mechanical nociceptive CLBP there are few, if any, options that provide similar evidence of safety, durability, and efficacy. In these particular patients, long-duration motor stimulation of the L2 medial branch should be standard of care.

References

1.Ward, S. R. et al. Architectural analysis and intraoperative measurements demonstrate the unique design of the multifidus muscle for lumbar spine stability. J. Bone Joint Surg. Am. 91, 176–185 (2009).
2.Gilligan, C. et al. An implantable restorative-neurostimulator for refractory mechanical chronic low back pain: a randomized sham-controlled clinical trial. Pain 162, 2486–2498 (2021).
3.Gilligan, C. et al. Three-Year Durability of Restorative Neurostimulation Effectiveness in Patients With Chronic Low Back Pain and Multifidus Muscle Dysfunction. Neuromodulation 26, 98–108 (2023).

Presenting Author

Chris Gilligan

Poster Authors

Christopher Gilligan

MD

Brigham and Women's Hospital

Lead Author

Topics

  • Treatment/Management: Interventional Therapies – Neuromodulation