Does Magnesium Sulfate as an Adjuvant of Local Anesthetics Facilitate Better Effect of Perineural Nerve Blocks?: A Meta-analysis of Randomized Controlled Trials.

To investigate the efficacy and safety of magnesium sulfate as an adjuvant of local anesthetics in perineural nerve blocks.Randomized controlled trials studying the effect and safety of magnesium sulfate in perineural nerve blocks were retrieved from online databases. The mean difference (MD), risk ratio, and their corresponding 95% confidence intervals (CIs) were calculated using RevMan 5.3 statistical software.Seven trials evaluating 493 patients were included. The pooled results from our meta-analysis showed that a combination of magnesium sulfate and local anesthetics in nerve blocks could result in longer postoperative duration time of analgesia (MD=124.66; 95% CI, 65.09-184.23; P<0.0001), longer duration time of sensory (MD=106.69; 95% CI, 60.93-152.45; P<0.00001) and motor block (MD=89.95; 95% CI, 50.89-129.00; P<0.0001). In addition, magnesium sulfate in nerve blocks was also associated with significantly quick onset of motor block (MD=-1.17; 95% CI, -1.73 to -0.60; P<0.0001). For onset time of sensory block, number of patients requiring supplementary analgesics, and incidence of postoperative nausea and vomiting, no statistically differences were observed between the 2 groups.The present study suggests that combined magnesium sulfate and local anesthetics in perineural nerve blocks provided better analgesic efficacy. For it prolongs the postoperative duration time of analgesia, sensory and motor block without increasing the short-term side effects. Magnesium sulfate may be a promising analgesic for perineural nerve blocks, but further studies are required to validate our results.