Peripheral Nerve Stimulation Using High-Frequency Electromagnetic Coupling Technology to Power an Implanted Neurostimulator with a Separate Receiver at the Superior Cluneal Nerve for Treatment of Chronic Back Pain Due to Neuralgia: A Retrospective Study.

Background: Low back pain is a highly prevalent condition with substantial costs. Superior cluneal neuralgia is present in up to 14% of low back pain cases. This etiology of back pain is often overlooked because the symptoms of superior cluneal neuralgia manifest similarly to those of other conditions, such as radiculopathy and sacroiliac joint pain. Peripheral nerve stimulation (PNS) is an emerging pain management modality used to treat various chronic pain conditions. This retrospective study will examine the outcomes of patients who have back pain caused by neuralgia and are treated with the permanent Freedom® PNS System (Curonix LLC) at the superior cluneal nerve.

Objectives: The primary objective was to examine the responder rate (proportion of patients who experienced greater than 50% relief) and changes in pain scores after the trial procedure. Secondary objectives included changes in pain scores from at least one month after permanent implantation, adverse event occurrences, changes in function and quality of life, and reductions in medication usage.

Setting: This was a retrospective single-site study. All procedures were performed by the same interventional pain physician.

Methods: A retrospective chart review was conducted to assess baseline and follow-up parameters. Inclusion criteria consisted of requirements that patients be 18 years or older and have a confirmed superior cluneal neuralgia diagnosis responsible for their pain presentation. Exclusion criteria included the presence of another active implanted device for pain management. The 11-point verbal rating scale (VRS) was used to assess pain scores.

Results: Twenty-one patients were included in this study. All 21 responded to the trial procedure with a 77% average reduction in VRS scores. At the follow-up (mean = 11 months), 20 patients reported an average 57% reduction in pain scores with the verbal rating scale. The same proportion of patients reported improved function and quality of life. Five patients reported reduced medication usage, including one who stopped taking pain medication altogether. No complications were reported.

Limitations: We were limited to the data available in the patient charts since this was a retrospective study investigating the efficacy and safety of the Freedom® PNS System for patients with refractory chronic back pain.

Conclusion: When used to target the superior cluneal nerve, the Curonix Freedom® PNS System is an effective and safe treatment for neuralgia-caused chronic lower back pain resistant to conservative therapy.