Five-Year Longitudinal Follow-up of Restorative Neurostimulation Shows Durability of Effectiveness in Patients With Refractory Chronic Low Back Pain Associated With Multifidus Muscle Dysfunction

Background Adults with refractory, mechanical chronic low back pain associated with impaired neuromuscular control of the lumbar multifidus muscle have few treatment options that provide long-term clinical benefit. This study hypothesized that restorative neurostimulation, a rehabilitative treatment that activates the lumbar multifidus muscles to overcome underlying dysfunction, is safe and provides relevant and durable clinical benefit to patients with this specific etiology. Materials and Methods In this prospective five-year longitudinal follow-up of the ReActiv8-B pivotal trial, participants (N = 204) had activity-limiting, moderate-to-severe, refractory, mechanical chronic low back pain, a positive prone instability test result indicating impaired multifidus muscle control, and no indications for spine surgery. Low back pain intensity (10-cm visual analog scale [VAS]), disability (Oswestry Disability Index), and quality of life (EuroQol’s “EQ-5D-5L” index) were compared with baseline and following the intent-to-treat principle, with a supporting mixed-effects model for repeated measures that accounted for missing data. Results At five years (n = 126), low back pain VAS had improved from 7.3 to 2.4 cm (−4.9; 95% CI, −5.3 to −4.5 cm; p < 0.0001), and 71.8% of participants had a reduction of ≥50%. The Oswestry Disability Index improved from 39.1 to 16.5 (−22.7; 95% CI, −25.4 to −20.8; p < 0.0001), and 61.1% of participants had reduction of ≥20 points. The EQ-5D-5L index improved from 0.585 to 0.807 (0.231; 95% CI, 0.195–0.267; p < 0.0001). Although the mixed-effects model attenuated completed-case results, conclusions and statistical significance were maintained. Of 52 subjects who were on opioids at baseline and had a five-year visit, 46% discontinued, and 23% decreased intake. The safety profile compared favorably with neurostimulator treatments for other types of back pain. No lead migrations were observed. Conclusion Over a five-year period, restorative neurostimulation provided clinically substantial and durable benefits with a favorable safety profile in patients with refractory chronic low back pain associated with multifidus muscle dysfunction. Clinical Trial Registration The Clinicaltrials.gov registration number for the study is NCT02577354; registration date: October 15, 2016; principal investigator: Christopher Gilligan, MD, Brigham and Women’s Hospital, Boston, MA, USA. The study was conducted in Australia (Broadmeadow, New South Wales; Noosa Heads, Queensland; Welland, South Australia; Clayton, Victoria), Belgium (Sint-Niklaas; Wilrijk), The Netherlands (Rotterdam), UK (Leeds, London, Middlesbrough), and USA (La Jolla, CA; Santa Monica, CA; Aurora, CO; Carmel, IN; Indianapolis, IN; Kansas City, KS; Boston, MA; Royal Oak, MI; Durham, NC; Winston-Salem, NC; Cleveland, OH; Providence, RI; Spartanburg, SC; Spokane, WA; Charleston, WV).