Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 64 9 2026 08 11 604 611 Asma Amiri Clinical Research Development Unit, Imam Khomeini Hospital, Jiroft University of Medical Sciences, Jiroft, Iran. AND Pain Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. Shima Kazemzadeh School of Medicine, Imam Khomeini Hospital, Jiroft University of Medical Sciences, Jiroft, Iran Ehsan Movahed Department of Public Health, School of Health, Jiroft University of Medical Sciences, Jiroft, Iran. AND Social Determinants of Health Research Center, Institute for Future Studies in Health, Kerman University of Medical Sciences, Kerman, Iran Babak Eslami Pain Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran AND Department of Anesthesiology, Critical Care, and Pain Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran 2026 04 30 2026 06 13 Post-dural puncture headache (PDPH) is a common complication of spinal anesthesia. This trial compared the impact of paramedian versus midline approaches on PDPH incidence in orthopedic patients. This randomized controlled trial enrolled 160 orthopedic surgery candidates at Imam Khomeini Hospital, Jiroft (2023). Randomization was performed using computer-generated numbers and sealed opaque envelopes for allocation concealment (1:1 ratio). Patients received spinal anesthesia via paramedian (Group P, n=80) or midline (Group M, n=80) approach using a 25-G Quincke needle. The anesthesiologist performing the block could not be blinded to the technique; however, participants, outcome assessors (neurologist), and data analysts were blinded. PDPH was diagnosed according to ICHD 3 criteria (headache developing within 5 days, postural component, and associated symptoms). Incidence, duration, severity, and onset timing were recorded. Odds ratio (OR) with 95% confidence interval (CI) was calculated for the primary outcome. PDPH occurred in 31.3% of Group P vs. 62.5% of Group M. The midline group had significantly higher odds of PDPH (OR=3.67, 95% CI: 1.98-6.80, P<0.001). Mean headache duration was 2.56 days (Group P) vs. 5.34 days (Group M). Most headaches in both groups began within the first 24 hours. The paramedian technique significantly reduces the incidence, duration, and severity of PDPH compared to the midline approach. Adoption of the paramedian technique is recommended to improve patient outcomes. https://acta.tums.ac.ir/index.php/acta/article/view/12104 https://acta.tums.ac.ir/index.php/acta/article/download/12104/6108