Effect of modified anterior approach for ultrasound-guided superior laryngeal nerve block on sore throat after tonsillectomy in adults: study protocol for a double-blind randomised controlled trial

Introduction Postoperative sore throat (POST), a common complication following tonsillectomy, significantly impairs patient recovery through persistent pain and dysphagia. The internal branch of superior laryngeal nerve block (iSLNB) can effectively alleviate POST. Specifically, the ultrasound (US)-guided modified anterior approach for iSLNB offers anatomical precision and reduced invasiveness compared with traditional approaches. This study aims to determine whether the US-guided modified anterior approach for iSLNB can relieve POST in adults after tonsillectomy. Methods and analysis A total of 40 patients scheduled for elective tonsillectomy under general anaesthesia will be randomly allocated to either the nerve block group (US-guided modified anterior iSLNB group) or the blank control group (only US scanning). Following the induction of general anaesthesia, the corresponding interventions will be performed, followed by postoperative pain assessment. The main outcome will be the POST intensity during swallowing at 24 hours after surgery. Secondary outcomes will consist of (a) the level of POST at rest at the same 24-hour postoperative time point; pain intensity measurements at rest and while swallowing recorded at 1 hour, 6 hours, 48 hours and on postoperative day 7; (b) the incidence of total pain at 24 hours postoperatively; (c) the time until the first administration of rescue analgesia and the cumulative dosage of rescue analgesic drugs consumed; (d) pain satisfaction; (e) perioperative haemodynamic parameters and (f) the incidence of perioperative complications. This article will outline the study methodology of the randomised controlled trial. Ethics and dissemination The study protocol has received ethical approval from the Ethics Committee of West China Hospital, Sichuan University (Audit No. 757 of 2025), and has been formally registered with the Chinese Clinical Trial Registry ( www.chictr.org.cn ). Findings will be disseminated through publication in a peer-reviewed academic journal. Trial registration number ChiCTR2500102999.