Perineural versus intravenous dexamethasone for single-shot interscalene block in arthroscopic shoulder surgery: a systematic review and meta-analysis of studies published through May 2021

Abstract

Although both perineural and intravenous dexamethasone have been shown to extend the analgesic duration of single-shot interscalene brachial plexus blocks (ISB), the optimal route of administration remains uncertain. This meta-analysis systematically compares the efficacy and safety of perineural versus intravenous dexamethasone as adjuvants to ISB in patients undergoing arthroscopic shoulder surgery. Primary outcomes assessed were analgesia duration, sensory block duration, and motor block duration. Secondary outcomes included postoperative pain scores, opioid consumption, and the incidence of adverse events, such as local anesthetic systemic toxicity (LAST). We systematically searched PubMed, Embase, and Web of Science from inception to May 31, 2021 under a prespecified protocol; studies published thereafter were beyond the scope of this review. A total of seven studies involving 846 patients were included in this analysis. Compared with intravenous administration, perineural injection of dexamethasone significantly prolonged analgesia duration (weighted mean difference WMD: 1.699 h; 95% confidence interval CI: 0.014–3.384; p = 0.048) and reduced postoperative pain scores at 12 h (WMD: −0.652; 95% CI: −1.129 to −0.176; p = 0.007). No significant differences were observed in sensory or motor block durations, postoperative pain scores, and opioid consumption at 24 h, or the incidence of adverse events, including dyspnea, sleep disturbances, and postoperative glucose level fluctuations. Compared with the intravenous route, perineural dexamethasone modestly prolongs the duration of analgesia after single-shot interscalene block (approximately 2 h). However, the associated reductions in postoperative pain scores are small and unlikely to reach commonly cited MCID thresholds, rendering the overall clinical importance uncertain. These findings support cautious interpretation and individualized route selection rather than generalized claims of superiority.