Effect of Perioperative Intravenous Lidocaine on Rebound Pain After Interscalene Brachial Plexus Block for Arthroscopic Rotator Cuff Repair: A Randomized Placebo-Controlled Trial

BACKGROUND: Rebound pain after single-shot interscalene brachial plexus block may diminish the early analgesic benefit of regional anesthesia after shoulder arthroscopy. We evaluated whether perioperative intravenous lidocaine reduces rebound pain after arthroscopic rotator cuff repair. METHODS: In this single-center randomized, placebo-controlled Phase II trial, 120 adults receiving interscalene block plus general anesthesia were allocated 1:1 to saline or lidocaine. Lidocaine was given as a 1 mg/kg ideal-body-weight loading dose before induction followed by 2 mg·kg-1·h-1 from skin incision to closure. The primary outcome was rebound pain within 24 hours. RESULTS: Rebound pain occurred in 14/60 participants (23.3%) with lidocaine and 22/60 (36.7%) with saline [risk difference -13.3%, 95% confidence interval (CI) -28.8% to 3.1%; relative risk 0.64, 95% CI 0.36-1.12; P = 0.163]. Median peak movement-evoked numerical rating scale scores were 5 in both groups (P = 0.136). The mean intraoperative remifentanil infusion rate was lower with lidocaine (mean difference -81.67 μg/h, 95% CI -101.47 to -61.86; P < 0.001). Baseline-adjusted discharge University of California, Los Angeles (UCLA) Shoulder Scores were higher and postoperative 9-item Central Sensitization Inventory (CSI-9) scores were lower with lidocaine (both P < 0.001); these outcomes were exploratory. Although 60 participants per group were enrolled, a corrected post hoc calculation indicated that approximately 82 evaluable participants per group were required for the prespecified effect. The lower composite adverse-event rate was mainly attributable to less propofol injection pain. CONCLUSION: This trial did not establish a statistically significant reduction in 24-hour rebound pain with perioperative intravenous lidocaine. Because the study was potentially underpowered, a clinically meaningful effect cannot be excluded. Lidocaine was associated with a lower mean intraoperative remifentanil infusion rate, whereas other recovery findings were exploratory. Larger adequately powered trials are needed before lidocaine can be recommended to prevent rebound pain. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2500103951; registered June 9, 2025. Registry record: https://www.chictr.org.cn/hvshowproject.html?id=278342andv=1.0.