Percutaneous electrical nerve stimulation as alternative to nerve blocks for the diagnosis of facet joint syndrome in patients with non-specific chronic low back pain: a clinical trial protocol

The diagnosis of chronic low back pain is frequently complicated by the absence of identifiable pathoanatomical causes on imaging. Consequently, clinical guidelines often advocate for interventional diagnostic procedures, such as medial branch nerve blocks, for suspected facet joint syndrome. Despite their utility, these interventions involve significant resource costs and potential risks associated with needle gauges and pharmacological agents. This study describes a protocol to evaluate percutaneous electrical nerve stimulation (PENS) as a safer, drug-free, and more cost-effective alternative. A parallel and multicenter study with an experimental design through a randomized clinical trial will be conducted. Adults with chronic low back pain and facet-mediated pain confirmed by two positive comparative medial branch diagnostic blocks will be randomized into four parallel groups: PENS, diagnostic medial branch nerve block (with local anesthetic), PENS + nerve block, and PENS + placebo block (full block ritual without active perineural anesthetic). The primary outcomes will be analgesic response. Secondary outcomes include pressure pain threshold, disability, health-related quality of life, rescue analgesic consumption, and the incidence/severity of local and systemic adverse events.
Clinical Trial Registration: The www.clinicaltrials.gov identifier is NCT07273006.
Chronic low back pain is very common, but in many people scans do not clearly show where the pain is coming from. When doctors suspect that the small joints in the spine, called facet joints, are the source, they often use a diagnostic nerve block. This involves injecting local anesthetic near the nerves that supply these joints to see whether the pain improves. Although this method can be useful, it requires drugs, larger needles, and medical resources, and it may cause side effects or complications. This study will test whether percutaneous electrical nerve stimulation (PENS) could be a simpler and safer alternative. PENS uses a very fine needle and a small electrical current, but no anesthetic drug. The study will include adults with long-lasting low back pain whose pain has already been linked to the facet joints by standard diagnostic blocks. Participants will be randomly assigned to one of four groups: PENS alone, standard nerve block, PENS plus nerve block, or PENS plus a placebo block. The main aim is to see whether PENS reduces pain as well as the standard nerve block immediately after treatment. The study will also examine physical function, sensitivity to pressure, quality of life, use of pain medicine, patient satisfaction, and side effects over the following week. If PENS performs similarly, it could become a less invasive option for helping identify facet-related low back pain.