Efficacy of magnesium sulfate as an adjuvant to local anesthetics in supraclavicular brachial plexus block: a meta-analysis of randomized trials

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BACKGROUND: Magnesium Sulfate (MS) maintains physiological functions in the body. Studies suggest its safety in regional anesthesia, despite off-label perineural use. We conducted a systematic review and meta-analysis to evaluate MS efficacy as an adjuvant in supraclavicular brachial plexus block. METHODS: The study was registered in PROSPERO (CRD42025641627) on 01/21/2025. We searched PubMed, Embase, Cochrane, clinicaltrials.gov and gray literature for eligible studies. We included RCTs that: enrolled adult patients; involved orthopedic surgery with supraclavicular block; compared LA alone versus LA with MS; and reported primary outcomes. Primary outcomes were duration of sensory and motor block, while secondary outcomes included onset of sensory and motor block, PONV and rescue analgesia needs postoperatively. RoB2 tool and GRADE assessed bias risk and evidence certainty. Variables were examined using DerSimonian-Laird random-effects model. RESULTS: Analysis included 10 studies and 734 patients. The intervention group showed longer sensory and motor block than controls. The Mean Difference (MD) was 180.84 minutes (95% CI [154.09, 207.59], 95% PI [71.67, 289.77], p < 0.00001, I² = 97%) and 151.26 minutes (95% CI [99.78, 202.74], 95% PI [-23.12, 325.63], p < 0.00001, I² = 99%). The magnesium group showed statistical difference in onset of sensory and motor blockade and rescue analgesia needs, with no difference in PONV. Evidence certainty was rated low to moderate. Risk of bias "high" in three studies, "some concerns" in four studies and "low" in three studies. CONCLUSION: Our meta-analysis supports MS as adjuvant in supraclavicular block. Further research is needed due to high heterogeneity. PROSPERO REGISTRATION: CRD42025641627.