Lidocaine vs. Other Local Anesthetics in the Development of Transient Neurologic Symptoms (TNS) Following Spinal Anesthesia: A Meta-Analysis of Randomized Controlled Trials

Figure 1. Flow diagram of the included and excluded studies. A total of 4515 articles were found during the literature search. Among them, 2493 articles were duplicated retrievals. A total of 2202 articles and 168 articles were obviously irrelevant studies. We excluded 84 articles due to various reasons. Finally, 39 articles were included in the final analysis. Abbreviations: TNS = transient neurological symptoms, LA = local anesthetics, RCT = randomized controlled trial

Figure 2. Risk of bias summary and graph using the Cochrane Risk of Bias tool [20]. The randomization and allocation concealment were well performed in most studies, but the method was not described in several studies. The performance bias was unclear or high in most studies, whereas the detection bias was low overall. The risk of attrition bias, reporting bias and other biases were low in most studies. Abbreviations: + = low risk of bias, ? = unclear risk of bias, - = high risk of bias.

Figure 3. Forest plot for the risk of transient neurologic symptoms (TNS) after spinal anesthesia with lidocaine versus other local anesthetics. The incidence of TNS 10.8 % in the lidocaine group while 2.2% in the control group. The risk of TNS was significantly higher in the lidocaine group than in the control group (p < 0.001). Abbreviations: LDC = lidocaine, LA = local anesthetics, RR = risk ratio, CI = confidence interval.

Figure 4. Forest plot for subgroup analysis. A subgroup analysis was conducted according to the local anesthetics which were used in the control group. The incidence of TNS was significantly higher in the lidocaine group than in the bupivacaine (p < 0.001), levobupivacaine (p < 0.001), prilocaine (p = 0.001), chloroprocaine (p = 0.037), procaine (p = 0.003) and articaine group (p < 0.001). However, there were no differences in the risk of TNS between the lidocaine group and mepivacaine (p =0.728), ropivacaine (p = 0.052) and sameridine group (p = 0.545). Abbreviations: LDC = lidocaine, LA = local anesthetics, CI = confidence interval.

Figure 5. Forest plot for subgroup analysis. Additional subgroup analyses were conducted according to the baricity or concentration of the lidocaine. The risk of TNS was significantly higher in hyperbaric (p < 0.001), isobaric lidocaine group (p < 0.001) compared to the control group. In terms of concentration, lidocaine showed a higher incidence of TNS regardless of concentrations compared to the control group (p < 0.05). Abbreviations: LDC = lidocaine, LA = local anesthetics, CI = confidence interval.