Incidence of hemidiaphragmatic paralysis in superior trunk versus interscalene block upper limb surgeries: a systematic review, meta-analysis, and trial sequential analysis.

Abstract

Background: Interscalene block (ISB) is widely used for upper limb surgery but frequently causes hemidiaphragmatic paralysis (HDP). Superior trunk block (STB) has emerged as a promising alternative that preserves phrenic nerve. This study aimed to evaluate whether STB is a safer option than ISB.

Methods: This systematic review and meta-analysis followed PRISMA guidelines and was registered in PROSPERO (CRD420250654685). Randomized controlled trials (RCTs) comparing STB and ISB in adults undergoing upper limb surgery and reporting HDP as the primary outcome were included. Secondary outcomes were postoperative pain, opioid consumption, motor block duration, patient satisfaction, and Horner's syndrome. Comprehensive searches were conducted through June 2025 in PubMed, Scopus, Embase, Cochrane, and Web of Science. Data were analyzed using a random-effects model in R, and trial sequential analysis was applied to assess statistical robustness.

Results: Eight RCTs involving 597 patients were included. Compared with ISB, STB significantly reduced the incidence of complete HDP (risk ratio [RR], 0.10; 95% confidence interval [CI], 0.07-0.17; I2 = 0%, P < 0.001) and Horner's syndrome (RR, 0.06; 95% CI, 0.01-0.24; I2 = 0%, P < 0.001). No significant differences were observed in opioid consumption (P = 0.262), pain scores (P = 0.661), patient satisfaction on a 0-10 scale (P = 0.117), or motor block duration (P = 0.624).

Conclusions: STB provides postoperative analgesia comparable to ISB while significantly reducing the incidence of HDP and Horner's syndrome, supporting its role as a safer and effective alternative for shoulder surgery.