Patient-reported propagated sensation along meridians during acupuncture for lumbar disc herniation: protocol for an exploratory prospective cohort study with multimodal neurophysiological and immune measurements

Background Propagated sensation along meridians (PSM) refers to the radiation of needling sensation beyond the needling site along meridian pathways. In traditional acupuncture theory, PSM has long been considered an important factor associated with clinical efficacy, particularly in conditions like lumbar disc herniation where pain radiates along the lower limb. However, this phenomenon has not been well characterized by modern neurobiological methods. Whether patients who report PSM show distinct autonomic, sensory, or motor responses, and whether this relates to better outcomes, remains unclear. In this study, we aim to explore the clinical and physiological correlates of patient-reported PSM in a cohort of LDH patients receiving standardized acupuncture. Methods and analysis This single-center, prospective, observational cohort study will enroll 204 LDH patients with radicular pain. Participants will be classified into three groups based on PSM reporting across three treatment sessions corroborated by assessor-documented needle-evoked muscle twitches: PSM-positive, PSM-negative, and indeterminate. The primary endpoint is the clinical improvement rate based on Japanese Orthopaedic Association (JOA) scores. Secondary endpoints include pain intensity (VAS), functional status (JOA), multimodal neurophysiological parameters (EEG, sEMG, EDA, EOG), serological cytokine profiles (IL-1 β , IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-17, IFN-γ, TNF- α , and IFN- α ), and the Massachusetts General Hospital Acupuncture Sensation Scale (MASS) administered post-session to quantify PSM intensity and spreading. Data will be analyzed using linear mixed-effects models, with results reported as effect estimates with 95% confidence intervals and false discovery rate correction within signal families; exploratory multimodal analyses will be used to identify physiological features associated with PSM. Expected results We hypothesize that the PSM-positive cohort will show greater clinical improvement than the PSM-negative cohort, with larger reductions in radicular pain and better functional recovery following standardized acupuncture. Clinical trial registration ITMCTR2025001534, https://itmctr.ccebtcm.org.cn .