Bilateral superficial cervical plexus block in combination with general anesthesia has a low efficacy in thyroid surgery: a meta-analysis of randomized controlled trials.

BACKGROUND A combination of bilateral superficial cervical plexus block (BSCPB) and general anesthesia is recommended for thyroid surgery. Proof of the efficacy of this combination remains weak. Furthermore, data on the safety of this regimen are lacking. Therefore, a meta-analysis of randomized controlled trials (RCT) to evaluate the efficacy and safety of BSCPB as an adjunct to general anesthesia in patients receiving thyroid surgery was performed. METHODS A meta-analysis of RCT was performed that included interventional groups evaluating the efficacy of BSCPB 6 and 24 hours after thyroid surgery. RESULTS Eight RCT, including a total of 799 patients (463 who underwent BSCPB and 336 controls), were analyzed. A meta-analysis demonstrated a reduction in pain scores 6 hours (Hedges' g: -0.46 [95% CI: -0.74 to -0.19]; p=0.001) and 24 hours postoperatively (Hedges' g: -0.49 [95% CI: -0.71 to -0.27]; p<0.001) in patients who had undergone BSCPB. The relative risk for postoperative nausea and vomiting (PONV) was 0.80 (95% CI: 0.58 to 1.09, p=0.159) in patients receiving BSCPB. Procedure-related adverse events were reported in three of the 476 patients who had undergone BSCPB (0.6%; 95% CI: 0.1% to 2.0%). These three patients had transient paresis of the brachial plexus, combined with a diaphragmatic paresis in one case, and all spontaneously resolved. CONCLUSION The combination of BSCPB and general anesthesia has a significant benefit in reducing pain 6 and 24 hours after thyroid surgery. However, the effect on pain reduction is too small to be of clinical relevance. Although it is a safe procedure, the existing evidence allows for no recommendation concerning the application of BSCPB in thyroid surgery. Further trials should evaluate a dose-response relationship and the incidence of PONV with this regimen.