In Response.

Abstract

Thank you Dr Raghuraman1 for the thoughtful insights and comments on both the study by Barrington et al,2 as well as our editorial.3 The main purpose of the editorial was to promote awareness of the complex anatomy of the chest wall and breast to assure that the choice of block is appropriate for the various types of surgery. It is clear that you apply an intricate understanding of this anatomy, but we would like to clarify 2 items. While we very much agree that the medial and lateral pectoral nerves are mixed sensory and motor nerves that innervate the pectoralis major and minor muscles and their associated fascia, there is no evidence that they provide any sensory innervation to the skin, subcutaneous tissue, or breast parenchyma.4 Thus, there is no anatomic basis to support the theory that blockade of these nerves would provide analgesia for wide local excision (WLE) surgery. For surgeries such as WLE that only violate the skin and subcutaneous tissue (including breast parenchyma), the benefit of PECS II block stems from blockade of the lateral cutaneous branches of the intercostal nerves.4 You also mention the recent trial by Altiparmak et al.5 We would hesitate to place much emphasis on the findings of this study given 2 significant methodological issues with its protocol. First, the reported sample size was changed from 30 to 38 after patient recruitment was completed. Second, the reported primary outcome was changed from pain to tramadol consumption after the end of patient enrollment. In general, any future evidence to support a benefit for PECS II block over erector spinae plane block (ESPB) in surgeries that violate the chest wall muscles or facia, for example, modified radical mastectomy (MRM), would not be surprising. PECS II block targets the brachial plexus nerves supplying these muscles and fascia in addition to the lateral cutaneous branches of the intercostal nerves, while ESPB presumably blocks the intercostal nerves and their branches but spares the brachial plexus nerves. Pain from MRM surgery is multifactorial, but disruption of the deep chest wall fascia that is innervated by the brachial plexus likely plays a very significant role in postoperative pain. Robert B. Maniker, MD, MSDepartment of Anesthesiology and Perioperative MedicineColumbia University College of Physicians and SurgeonsNew York, New York[email protected]Rebecca L. Johnson, MDDepartment of AnesthesiologyMayo Clinic College of MedicineRochester, MinnesotaDe Q. Tran, MD, FRCPCDepartment of AnesthesiaMcGill UniversityMontreal, Quebec, Canada