Perineural Dexamethasone Added to Local Anesthesia for Brachial Plexus Block Improves Pain but Delays Block Onset and Motor Blockade Recovery

Background: Multiple studies have shown that perineural dexamethasone improvespostoperative analgesia. However, some studies have shown minimal benefit, and have raisedconcerns regarding adverse physio-chemical effects of perineural dexamethasone. Furthermore,there is a paucity of studies wherein control (IV) dexamethasone was considered.Objective: The purpose of this meta-analysis was to evaluate the effectiveness of differentconcentrations of perineural dexamethasone injection on postoperative analgesia, as well ascomplications from its use for brachial plexus blocks.Methods: A systematic literature search was conducted using the Cochrane Central Registryof Controlled Trials, PubMed, and Scopus. Trials comparing control and local dexamethasonetreated groups, and those which reported duration of analgesia and/or pain scores/opioidconsumptions were selected. Meta-analysis was performed using the Review Manager (RevMan)software 5.1.Results: Fourteen studies consisting of a total of 1,022 patients were included. Perineuraldexamethasone significantly prolonged the duration of postoperative analgesia in patientsreceiving both low-dose (4 – 5 mg) [SMD 2.41 (95% CI: 1.47, 3.35 P = 0<0.00001) I2 = 82%],and higher-doses (8 – 10 mg) [SMD 4.46 (95% CI 3.54, 5.38 P < 0.00001) I2 = 94%]. However,the duration of motor block was also prolonged [SMD 2.52 (95% CI: 1.06, 3.98 P = 0.0007) I2= 97%] and dexamethasone delayed latency of onset of sensory [SMD -0.49 (95% CI: -0.89,-0.09 P = 0.02) I2 = 76%] and motor [SMD -0.56 (95% CI: -1.13, 0.00 P = 0.05) I2 = 87%]blocks. Postoperative pain scores were improved at both 24 hours [SMD -1.46 (95% CI: -2.43,-0.50 P = 0.003) I2 = 95%] and 48 hours [SMD -1.20 (95% CI: -2.26, -0.13 P = 0.03) I2 = 95%]in dexamethasone-treated groups, whereas opioid consumption was reduced only at 48 hours[SMD -2.97 (95% CI: -4.17, -1.76 P < 0.00001) I2 = 88%]. Complications were comparablebetween control and dexamethasone-adjuvant groups, except for the excessively prolongednerve block that was observed predominantly in the dexamethasone-adjuvant group.Limitations: The limitations include different definitions used for the measurements of certainparameters such as the duration of analgesia and duration of motor block, number of studiesassessing certain parameters having high heterogeneity, and varying types of local anestheticsused in various studies.Conclusions: Perineural dexamethasone addition to local anesthetic solutions significantlyimproved postoperative pain in brachial plexus block without increasing complications.However, perineural adjuvant dexamethasone delayed the onset of sensory and motor block,and prolonged the duration of motor block. Smaller doses of dexamethasone (4 – 5 mg) wereas effective as higher doses (8 – 10 mg).Key words: Dexamethasone, perineural, brachial plexus block, postoperative pain, metaanalysis, systematic review