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.