Comparative Effectiveness of Suprascapular Nerve Block in the Relief of Acute Post-Operative Shoulder Pain: A Systematic Review and Meta-analysis.

BACKGROUND The suprascapular nerve accounts for 70% of shoulder sensory innervations, and suprascapular nerve block (SSNB) has been shown to be effective in the relief of chronic shoulder pain including rotator cuff tendinitis, subdeltoid impingement syndrome, and adhesive capsulitis. However, this remains inconclusive for patients undergoing surgery. The present meta-analysis aimed to explore the effectiveness of SSNB for relieving acute post-operative shoulder pain. OBJECTIVE To explore the effectiveness of SSNB for relieving acute post-operative shoulder pain. STUDY DESIGN A systematic review and meta-analysis. SETTING Services of general surgery, orthopaedics, and anaesthesiology. METHODS A systematic search of studies on SSNB for post-operative shoulder pain was conducted mainly in PubMed and Scopus. The standardized mean difference (SMD) of post-operative pain scales of SSNB versus placebo was treated as the primary outcome, whereas the odds ratio of nausea of SSNB versus placebo comprised the secondary outcome. RESULTS The meta-analysis included 7 randomized controlled trials and 2 comparative studies comprising 681 participants in total. The quantitative analysis showed a significantly lower pain level of SSNB versus placebo in the shoulder surgery patient group (SMD: -0.33; 95% confidence level [CI]: -0.51 to -0.15), but not in the non-shoulder surgery group (SMD: 0.28; 95% CI: -0.37 to 1.93). The pooled odds ratio of nausea in the SSNB arm compared with the placebo arm was 0.20 (95% CI: 0.09 to 0.45), indicating a reduction in the incidence of nausea following SSNB. LIMITATIONS Heterogeneity of included trials. CONCLUSIONS SSNB significantly reduced acute post-operative shoulder pain in the shoulder surgery group but not in patients undergoing laparoscopic surgery or thoracotomy. This suggests that SSNB can be used as a method of polymodal analgesia for patients undergoing shoulder surgery; however, it is not recommended for the non-shoulder surgery patient population. KEY WORDS Suprascapular nerve, shoulder surgery, thoracotomy, laparoscopic surgery.