RESUMO
Subpectoral breast augmentation surgery under regional anesthesia requires the selective neural blockade of the medial and lateral pectoral nerves to diminish postoperative pain syndromes. The purpose of this cadaver study is to demonstrate a reliable ultrasound guided approach to selectively target the pectoral nerves and their branches while sparing the brachial plexus cords. After evaluating the position and appearance of the pectoral nerves in 25 cadavers (50 sides), a portable ultrasound machine was used to guide the injection of 10 ml of 0.2% aqueous methylene blue solution in the pectoral region on both sides of three Thiel's embalmed cadavers using a single entry point-triple injection technique. This technique uses a medial to lateral approach with the entry point just medial to the pectoral minor muscle and three subsequent infiltrations: (1) deep lateral part of the pectoralis minor muscle, (2) between the pectoralis minor and major muscles, and (3) between the pectoralis major muscle and its posterior fascia under ultrasound visualization. Dissection demonstrates that the medial and lateral pectoral nerves were well stained while leaving the brachial plexus cords unstained. We show that 10 ml of an injected solution is sufficient to stain all the medial and lateral pectoral nerve branches without a proximal extension to the cords of the brachial plexus.