Anterior Suprascapular Nerve Block Versus Interscalene Brachial Plexus Block for Shoulder Surgery in the Outpatient Setting A Randomized Controlled Patient- and Assessor-Blinded Trial

Background and Objectives: The interscalene brachial plexus block (ISB), a potent option to control pain after shoulder surgery, has notable adverse effects. The anterior suprascapular nerve block (SSNB) might provide comparable analgesia and cause less grip-strength impairment. These characteristics were studied in this randomized controlled patient- and assessor-blinded trial. Methods: Outpatients were randomized to single-shot ultrasound-guided SSNB (10 mL ropivacaine 1%) or ISB (20 mL ropivacaine 0.75%) before general anesthesia for arthroscopic shoulder surgery. Pain (Numerical Rating Scale, 0-10), grip strength, degree of satisfaction, and strength of recommendation were assessed. Results: We randomized 168 patients to each group and analyzed 164 in the SSNB group and 165 in the ISB group. Nerve blocks were successful in 98% of the patients from each group. Both procedures provided good postoperative analgesia, and the mean pain level for SSNB was slightly but significantly lower by 0.32 units (95% confidence interval, 0.18-0.46; P < 0.001) and noninferior given a margin of 1.1 units; P < 0.001. Within the first 24 hours, 162 (99%) of SSNB patients had unimpaired grip strength compared to 81 (49%) of ISB patients (P < 0.001). The multiple primary outcome, superior unimpaired grip strength, and noninferior pain control was significant; P < 0.001. Compared to ISB patients (n = 130 [79%]), significantly more SSNB patients (n = 150 [91%]) were satisfied/highly satisfied. Patients in the SSNB group were more likely to recommend the procedure highly. Conclusions: For outpatients undergoing arthroscopic shoulder surgery under general anesthesia, the SSNB seems preferable to ISB. It provides excellent postoperative analgesia without exposing patients to impaired mobility and to risks of the more potent but also more invasive ISB.