Durability of Symptom Relief with Restorative Neurostimulation for Mechanical Chronic Low Back Pain: Three-Year Follow-up Results of the Pivotal Trial: Track 3: Neurostimulation for Back and Leg Pain

ABSTRACT

Introduction: Mechanical chronic low back pain (CLBP) can be caused by impaired neuromuscular control and degeneration of the multifidus muscles, the most important stabilizers of the lumbar spine. An implantable Restorative Neurostimulation system bilaterally stimulates the medial branches of the L2 dorsal rami to override underlying multifidus inhibition to facilitate motor control restoration. A randomized sham-controlled pivotal trial provided evidence of safety, effectiveness and durability of this therapy (clinicaltrials.gov/show/NCT02577354).[1,2] Here we will report the three-year durability results. Materials / Methods: Eligible patients had activity limiting mechanical CLBP (VAS >=6cm;Oswestry Disability Index (ODI) >=21 points) despite medical management, which included at least pain medications and physical therapy. They had evidence of impaired multifidus motor control (positive prone instability test) and no indication for spine surgery. All patients were implanted with a Restorative Neurostimulation system (ReActiv8, Mainstay Medical, Dublin, Ireland). During the long-term follow-up phase, all participants delivered stimulation for up to 30 minutes twice daily eliciting repetitive, tonic multifidus contractions. Result(s) At baseline (N=204), participants were 47+/-9 years of age, had history of backpain for 14+/-11 years, had an average low back pain VAS of 7.3+/-0.7 cm, ODI of 39+/-10, EQ-5D of 0.585+/-0.174 points and had pain on 97+/-8% of days in the year prior to enrollment. Three-year data are available for 124 participants*. Average VAS improved by 5.0+/-2.4 cm, ODI by 23+/-15 points and EQ-5D by 0.223+/-0.199 (All P<0.0001);78% of participants had a >=50% VAS improvement;69% reported LBP-Resolution (VAS<=2.5 cm);65% had a >=20-point ODI improvement and 86% of participants were "definitely satisfied" with the treatment. Pain intensity and disability are interdependent symptoms and treatment success is determined by composite improvements in ODI and VAS 84% had a substantial improvement of >=50% in VAS and/or >=20points in ODI, and 59% had these improvements in both VAS and ODI. Of participants using opioids at baseline, 72% had voluntarily discontinued or decreased consumption. Overall safety compares favorably to other neurostimulation systems, and no lead migrations were observed. During the third year of follow-up, 6 participants requested device removal citing resolution of pain. Discussion(s) See conclusions. Conclusion(s) Restorative-Neurostimulation is an effective, durable, and safe treatment for patients with refractory, activity-limiting CLBP secondary to impaired multifidus neuromuscular control. Consistent with the restorative mechanism, improvements accrue progressively over time. *Twenty-five follow-ups pending (Covid-19 restrictions) Learning Objectives: 1. Understand the long term pain outcomes (three year outcomes) of restorative neurostimulation for refractory chronic low back pain. 2. Understand the long term function outcomes (three year outcomes) of restorative neurostimulation for refractory chronic low back pain. 3. Understand the long term safety outcomes (three year outcomes) of restorative neurostimulation for refractory chronic low back pain. Keywords nociceptive low back pain, multifidus, motor control, Restorative neurostimulation, chronic low back pain Copyright © 2022