Restorative Neurostimulation Improves Pain, Function and Strength in Patients with Persistent Mechanical Low Back Pain

Introduction: Persistent mechanical, nociceptive, low back pain can be a debilitating condition. Because it is exacerbated by everyday tasks such as cleaning, gardening, standing, working and lifting children, the functional loss in this condition can cause significant economic and emotional impact.

Multiple studies have shown that restorative neurostimulation can significantly reduce pain and disability in patients with mechanical low back pain associated with multifidus muscle dysfunction. No studies have reported upon the functional and strength outcomes of treatment.

This study aimed to assess the functional and strength outcomes of restorative neurostimulation in addition to outcomes in pain, disability and quality of life.

Methods: An ethics committee approved, prospective observational study was conducted on 50 consecutive patients with mechanical low back pain, derived from two independent surgeon practices, who underwent implantation of a multifidus motor stimulator system by a single surgeon. Pain, disability, function and strength measures were recorded by an independent exercise physiologist pre-therapy and at regular intervals to 12 months.

Results: Data through to 12 months post-implant was available for 48 patients. Two patients had their system removed prior to 12 months – one due to infection and one on request by the patient because of inadequate pain reduction. The cohort comprised 27 males and 21 females with a mean (SD) age of 56 (12) years, body mass index of 28.2 (4.2) kg/m2 and low back pain duration of 19 (13) years.

Significant improvements were observed in the functional measures of the 30-second sit to stand test (mean of 10 to 14 repetitions; p< 0.001) and the timed-up-and-go test (mean of 8.3 to 6.6 seconds; p< 0.001).

Maximum trunk extension and flexion force was significantly improved - maximum extension force increased from 133 to 276 N (p < 0.001) and maximum flexion force increased from 127 to 172 N (p < 0.001).

In total, 38/48 patients reported at least a 30% reduction in low back pain and/or a 15-point reduction in disability. The mean EQ-5D-5L score improved from 0.753 to 0.866 (p=0.002).

Conclusion: Objective assessments of function and trunk strength, along with subjective assessments of low back pain, disability and quality of life showed significant improvement with restorative neurostimulation in a cohort of individuals with persistent mechanical low back pain. Restoration of function and strength by the therapy supports the hypothesis that reversal of multifidus dysfunction is at least in part responsible for the clinical improvement in these patients.