Optic nerve sheath diameter as a real-time biomarker for epidural blood patch efficacy after post-dural puncture headache: a preliminary report

Post-dural puncture headache (PDPH) following epidural anesthesia remains a frequent obstetric complication. While epidural blood patch (EBP) is the reference treatment, its efficacy assessment still relies on subjective pain reporting. This study explored whether changes in optic nerve sheath diameter (ONSD) measured by ultrasound could serve as an objective, real-time indicator of early EBP response. In this prospective, single-center observational study, 30 postpartum patients with PDPH undergoing EBP had ONSD measured before (H0) and 2 h after (H2) the procedure. Correlation between ΔONSD and ΔVAS pain scores was analyzed with bootstrap validation, and receiver operating characteristic (ROC) analysis identified thresholds associated with early response. Mean ΔONSD was 0.97 ± 0.55 mm, significantly correlated with pain reduction (r = - 0.64, p < 0.001; bootstrap 95% CI: -0.81 to - 0.36). ROC analysis showed good diagnostic performance (AUC = 0.96, 95% CI: 0.87-1.00), with a ΔONSD ≥ 0.40 mm threshold providing 100% sensitivity and 83% specificity for early improvement. These preliminary findings suggest that ONSD ultrasound may offer a feasible, noninvasive adjunct for assessing early EBP response in PDPH. The identified 0.40 mm change threshold appears promising but requires confirmation in larger, multicenter studies with extended follow-up to determine its reproducibility and clinical utility.