BREAST Avoiding Denervation of Rectus Abdominis in DIEP Flap Harvest: The Importance of Medial Row Perforators Warren M. Rozen, M.B.B.S., P.G.Dip.Surg.Anat. Mark W. Ashton, M.B.B.S., M.D. Alice C. A. Murray, B.A. (Hons.) G. Ian Taylor, M.B.B.S., M.D. Parkville, Victoria, Australia Background: The deep inferior epigastric artery (DIEA) perforator flap for breast reconstruction spares rectus abdominis muscle and has low donor-site morbidity. However, abdominal wall weakness and bulge remain significant complications, with damage to the motor innervation of the rectus abdominis postulated as a cause. This study describes the relationship between the nerves supplying rectus abdominis and perforators, based on a thorough cadaveric study and review of the literature. Methods: Twenty hemiabdominal walls from fresh and embalmed cadavers were dissected, mapping the course of the nerve and vascular supply of rectus abdominis. Results: The infraumbilical segment of rectus abdominis was innervated by T9 –L1, with four to seven nerve branches entering rectus abdominis from its lateral border (12 cases) or posterior surface (93 cases). Each nerve entered a nerve plexus running with the most lateral branch of the DIEA, before running with arterial perforators into rectus abdominis. Nerves entered rectus muscle more medial than the lateral row perforators (83 percent of cases), with the medial branches of the DIEA devoid of these nerve branches. Conclusions: The nerves innervating rectus abdominis are at risk during the raising of a DIEA perforator flap. These nerves enter the posterior surface of rectus abdominis and run with the most lateral branch of the DIEA and its perforators. Damage to these nerves may denervate rectus abdominis muscle and contribute to donor-site morbidity. As medial row perforators were not related to these motor nerves, these perforators are ideal for inclusion in DIEA perforator and transverse rectus abdominis myocutaneous flaps. (Plast. Recon- str. Surg. 122: 710, 2008.) B reast reconstruction flaps based on the in- tegument of the lower abdominal wall have become the standard of care, based on both aesthetic outcome and operative morbidity. The transverse rectus abdominis myocutaneous (TRAM) flap has been used extensively for this purpose in the past; however, modifications to the technique have been introduced to spare the sacrifice of rectus abdominis muscle. The muscle-sparing TRAM flap has been described, with recent clas- sification systems used to describe the portion of rectus muscle spared. 1,2 The deep inferior epigastric artery (DIEA) perforator flap, as an extension of this concept, has become the standard procedure, as no muscle is included in the flap and the maximal amount of muscle is spared. First described in 1989 by Ko- shima and Soeda and developed for breast recon- struction by Allen and Treece in 1994, 3,4 many studies have since demonstrated an improvement in donor-site morbidity with DIEA perforator flaps over the previous methods. 2,5–13 However, abdom- inal wall weakness and abdominal bulge remain significant complications. Recent studies compar- From the Jack Brockhoff Reconstructive Plastic Surgery Re- search Unit, Department of Anatomy and Cell Biology, Uni- versity of Melbourne. Received for publication November 13, 2007; accepted Jan- uary 15, 2008. Copyright ©2008 by the American Society of Plastic Surgeons DOI: 10.1097/PRS.0b013e318180ed8b Disclosure: The authors declare that there is no source of financial or other support, or any financial or professional relationships that may pose a com- peting interest. www.PRSJournal.com 710