The Effect Of Scalp Nerve Block On Postoperative Analgesia And Stress Response In Patients Undergoing Craniotomy: A Meta-analysis

ObjectivePerioperative safety of craniocerebral surgery has long been concerned by surgeons and anesthesiologists.Stable intraoperative circulation can provide clear operating field and inhibit the stress cascade.Effective control of postoperative pain is beneficial to patient outcome.Scalp nerve block,as a traditional technique,has been studied more and more deeply.We used meta-analysis to evaluate the effect of scalp nerve block on postoperative analgesia and stress response in patients undergoing craniotomy.MethodsRandomized controlled clinical trials of scalp nerve block for elective craniotomy under general anesthesia were included in Pubmed,EMbase,Cochrane Library,CNKI and Wanfang databases through computer retrieval.The retrieval time was from August 1,2022 in the self-established database in English and Chinese.Literature retrieval,literature screening,quality evaluation and data extraction were carried out step by step by two researchers.Statistical analysis was performed using Rev Man 5.4 and Stata MP17.0.Subgroup analysis of pain score was performed at each time point after surgery according to different scalp nerve block time and local anesthetic agents,sensitivity analysis of each result was conducted,and heterogeneity was found in combination with Galbraith chart.Results1.Main outcome indicators:including pain scores at different time points after surgery and morphine consumption at 24 and 48 hours after surgery.1.1 The combined result of pain score I~2at each time point after surgery was greater than 50%,so random effects model was used for analysis.Results:Four studies reported pain scores at 0.5h after surgery(SMD=-0.99,95%CI-1.72～-0.25,P=0.008,I~2=82%);Eight studies reported pain scores 1h postoperatively(SMD=-1.25,95%CI-1.87～-0.63,P<0.0001,I~2=88%);Thirteen studies reported pain scores at 2h after surgery(SMD=-1.34,95%CI-1.80～-0.88,P<0.0001,I~2=89%);Six studies reported pain scores at 4h after surgery(SMD=-0.93,95%CI-1.57～-0.29,P=0.004,I~2=83%);Eleven studies reported pain scores at 6h after surgery(SMD=-1.10,95%CI-1.65～-0.56,P<0.0001,I~2=90%);Five studies reported pain scores at 8h after surgery(SMD=-0.51,95%CI-0.89～-0.14,P=0.007,I~2=60%);Nine studies reported pain scores12 hours after surgery(SMD=-1.31,95%CI-2.14～-0.49,P=0.002,I~2=94%);Fourteen studies reported pain scores 24 hours after surgery(SMD=-0.65,95%CI-1.03～-0.27,P=0.0009,I~2=88%);Ten studies reported pain scores 48 hours after surgery(SMD=-0.69,95%CI-1.23～-0.14,P=0.01,I~2=93%).Sensitivity analysis was performed for each result and a Galbraith map was drawn to find the source of heterogeneity.Studies causing significant heterogeneity were excluded and combined again.The results showed that pain score 0.5h after surgery(SMD=-0.57,95%CI-0.88～-0.25,P=0.0005,I~2=0%);Pain score 1h after surgery(SMD=-0.41,95%CI-0.69～-0.13,P=0.005,I~2=0%);Pain scores at 2h after surgery(SMD=-1.14,95%CI-1.44～-0.83,P<0.00001,I~2=60%);Pain scores at 4h after surgery(SMD=-0.71,95%CI-1.04～-0.38,P<0.0001,I~2=0%);Pain score 6h after surgery(SMD=-0.84,95%CI-1.11～-0.58,P<0.00001,I~2=8%);Pain scores at 8h after surgery(SMD=-0.30,95%CI-0.53～-0.06,P=0.01,I~2=0%);Pain scores 12 hours after surgery(SMD=-1.14,95%CI-1.59～-0.69,P<0.00001,I~2=25%);Pain score 24 hours after surgery(SMD=-0.45,95%CI-0.65～-0.24,P<0.0001,I~2=9%);Pain score 48h after surgery(SMD=-0.37,95%CI-0.71～-0.02,P=0.04,I~2=49%).Sensitivity analysis suggested stable results,and the direction of pain scores did not change at each time point after excluding studies that caused significant heterogeneity.1.2 Results of subgroup analysis1.2.1 Subgroup analysis of postoperative pain score according to different block timeThe results showed that compared with the control group,the analgesic effect of preoperative scalp nerve block lasted until 48 hours after operation.Scalp nerve block was performed after the operation,and the analgesic effect lasted until 8 hours after the operation.1.2.2 Subgroup analysis was conducted according to different local anestheticsThe results showed that Compared with the control group,the analgesic effects of ropivacaine and levobupivacaine lasted up to 48 h after surgery,whereas bupivacaine may only have some analgesic effect up to 8 h.1.3 Postoperative morphine consumptionThe combined results of morphine consumption at 24h and 48h after surgery were all greater than 50%,so random effects model was used for analysis.The results showed that morphine consumption at 24 hours after surgery(SMD=-0.44,95%CI-1.11～0.22,P=0.19,I~2=84%)was not reduced by scalp nerve block at 24 hours after surgery.Sensitivity analysis showed that morphine consumption at 24 hours after surgery was stable.After excluding any one study,the results were combined without changing the direction of results.The direction of the results did not change after Galbrestus diagram was drawn to find the source of heterogeneity and the studies that caused obvious heterogeneity were excluded.Morphineconsumption48hoursafter surgery(SMD=-0.44,95%CI-1.11～0.22,P=0.19,I~2=84%).Scalp nerve block could reduce morphine consumption 48 hours after surgery.Sensitivity analysis suggested that the results were unstable,and the results changed after Nguyen was removed.2Secondary outcome indicators:including first rescue analgesia time,stress hormone changes,hemodynamic changes and postoperative incidence of nausea and vomiting.2.1 Duration of first rescue analgesiaCompared with the control group,scalp nerve block reduced the first postoperative rescue analgesia time(SMD=1.01,95%CI0.30～1.72,P=0.005,I~2=89%).Sensitivity analysis showed that the results were stable.Galbraith plots were drawn to look for heterogeneity,and the direction of results did not change after excluding studies that caused high heterogeneity(SMD=0.92,95%CI 0.60～1.24,P<0.00001,I~2=20%).2.2 Changes of stress hormones2.2.1 AngiotensinⅡAngiotensinⅡ(AⅡ)was reported in only 2 studies before surgery(SMD=0.06,95%CI-0.43～0.55,P=0.82,I~2=54.53%).Peeling(SMD=-0.66,95%CI-2.02～0.71,P=0.35,I~2=93.32%);Intraoperative(SMD=-1.36,95%CI-3.21～0.50,P=0.15,I~2=95.54%);After surgery(SMD=-1.77,95%CI-2.16～-1.38,P<0.001,I~2=0%).Sensitivity analysis showed that the results were stable only at the two time points before and after surgery,suggesting comparability between studies.Moreover,scalp nerve block could inhibit the level of AⅡat the end of surgery compared with the control group.2.2.2 Blood GlucosePreoperative blood glucose levels(SMD=0.03,95%CI-0.23～0.28,P=0.84,I~2=29%);Blood glucose level(SMD=-0.87,95%CI-1.90～0.15,P=0.1,I~2=85.45%);Blood glucose level during scalp resection(SMD=-1.39,95%CI-2.54～-0.24,P=0.01,I~2=93.76%);Blood glucose level during bone flap removal(SMD=-1.64,95%CI-2.89～-0.38,P=0.02,I~2=92.41%);Intraoperativebloodglucoselevels(SMD=-1.86,95%CI-2.26～-1.46,P<0.00001,I~2=15%)blood glucose level at the end of surgery(SMD=-0.88,95%CI-2.85～1.09,P=0.38,I~2=97.35%).Sensitivity analysis showed that only preoperative and intraoperative blood glucose levels were stable,suggesting that preoperative baseline blood glucose levels were comparable between studies.Scalp nerve block reduced intraoperative stress-induced increases in blood glucose levels compared with controls.2.2.3 CortisolPreoperative cortisol levels(SMD=-0.09,95%CI-0.32～0.15,P=0.47,I~2=31.34%);Cortisol levels during scalp incision(SMD=-0.65,95%CI-1.14～-0.17,P=0.01,I~2=65.34%);Intraoperative cortisol levels(SMD=-1.10,95%CI-1.81～-0.39,P<0.001,I~2=82.64%)Cortisol levels after surgery(SMD=-0.94,95%CI-1.43～-0.45,P<0.001,I~2=63%).Sensitivity analysis showed that the cortisol levels before,during and after surgery were stable,suggesting that the baseline cortisol levels before surgery were comparable between studies.The Galbraith chart was used to find the source of heterogeneity,and the studies that caused high heterogeneity were excluded.The results showed that intraoperative Cor(SMD=-0.94,95%CI-1.43～-0.45,P<0.001,I~2=63%).After surgery,Cor(SMD=-0.71,95%CI-1.05～-0.37,P<0.0001,I~2=0%),and the direction of results did not change.These results indicated that scalp nerve block could inhibit the increase of cortisol level during and after operation compared with control group.2.3 Hemodynamic changesCompared with the control group,scalp nerve block inhibited the significant increase in heart rate at the time of pinning,scalp incision and surgery,and also inhibited the increase in mean arterial pressure at the time of pinning,scalp incision and surgery.Sensitivity analysis indicated that the results were stable,and the direction of results did not change after excluding the corresponding studies that caused high heterogeneity.However,further studies are needed to determine whether scalp nerve block can effectively inhibit changes in heart rate and mean arterial pressure during bone flap removal.2.4 Postoperative nausea and vomitingCompared with the control group,scalp nerve block reduced the incidence of postoperative nausea and vomiting(RR=0.71,95%CI 0.51～0.97,P=0.03,I~2=0.00%).ConclusionScalp nerve block can effectively relieve the pain of craniotomy patients within 48 hours after surgery,and effectively inhibit the stress response caused by surgical stimulation.