Clinical efficacy of the brachial plexus block via the posterior approach

Background and Objectives: The posterior approach to the brachial plexus remains underused. We assessed the clinical effectiveness of this technique for shoulder surgery. Methods: One hundred eighty-seven consecutive patients scheduled to undergo shoulder surgery were assessed after a single-injection nerve-stimulation technique using ropivacaine 0.75%. Sensory and motor block was evaluated in the distribution area of each terminal branch of the brachial plexus every 10 minutes for 30 minutes. Postoperative analgesia was evaluated at regular time intervals at rest and with passive movement, up to 24 hours postoperatively. Results: The brachial plexus was reached at a depth of 6.5 ± 0.9 cm. One attempt was sufficient in 85% of patients. Neck pain during insertion of the needle was encountered in 6 (3%; 95% confidence interval [CI], 0.7%-5.6%) patients. Thirty minutes after ropivacaine injection, the axillary, radial, median, musculocutaneous, and ulnar nerves were anesthetized in 100%, 100%, 97%, 96%, and 68% of cases, respectively. The success rate of the block was 98%. Postoperative analgesia was satisfactory in 97% of patients up to 12 hours after the initial injection. Dysphonia and Horner's syndrome were observed in 14 (7%; 95% CI, 3.7%-11.2%) and 12 (6%; 95% CI, 2.9%-9.9%) patients, respectively. One patient (0.5%; 95% CI, 0%-1.5%) had documented hemidiaphragmatic paresis. No complication was noted during the 3-month follow-up period. Conclusions: This study reports the clinical effectiveness of the single-injection nerve-stimulation technique for the brachial plexus block via the posterior approach in patients undergoing shoulder surgery. It appears to be effective, relatively safe, and well tolerated.