Avoiding Denervation of Abdominal Muscles during DIEP Flap Breast Reconstruction
By: Dr. Minas Chrysopoulo
The following interesting article was published in the "Plastic and Reconstructive Surgery" journal.
Avoiding Denervation of Rectus Abdominis in DIEP Flap Harvest II: An Intraoperative Assessment of the Nerves to Rectus by Rozen W, Ashton M, Kiil B, et al.
Plastic and Reconstructive Surgery:Volume 122(5) November 2008 pp 1321-1325.
Background: The deep inferior epigastric artery perforator (DIEP) flap aims to reduce donor-site morbidity by minimizing rectus muscle damage; however, damage to motor nerves during perforator dissection may denervate rectus muscle. Although cadaveric research has demonstrated that individual nerves do not arise from single spinal cord segments and are not distributed segmentally, the functional distribution of individual nerves remains unknown. Using intraoperative nerve stimulation, the current study describes the motor distribution of individual nerves supplying the rectus abdominis, providing a guide to nerve dissection during DIEP flap harvest.
Methods: Twenty rectus abdominis muscles in 17 patients undergoing reconstructive surgery involving rectus abdominis (DIEP, transverse rectus abdominis musculocutaneous, or vertical rectus abdominis musculocutaneous flaps) underwent intraoperative stimulation of nerves innervating the infraumbilical segment of the rectus. Nerve course and extent of rectus muscle contraction were recorded.
Results: In each case, three to seven nerves entered the infraumbilical segment of the rectus abdominis. Small nerves (type 1) innervated small longitudinal strips of rectus muscle, rather than transverse strips as previously described. There was significant overlap between adjacent type 1 nerves. In 18 of 20 cases, a single large nerve (type 2) at the level of the arcuate line supplied the entire width and length of rectus muscle.
Conclusions: Nerves innervating the rectus abdominis are at risk during DIEP flap harvest. Small, type 1 nerves have overlapping innervation from adjacent nerves and may be sacrificed without functional detriment. However, large type 2 nerves at the level of the arcuate line innervate the entire width of rectus muscle without adjacent overlap and may contribute to donor-site morbidity if sacrificed.
For DIEP flap surgery to be considered successful, several things need to occur:
1) the tissue (flap) transferred to the chest to create the new breast must survive fully.
2) the patient must not suffer any ill-effects from removal of the tissue ("flap") from the abdomen. This is known as "donor-site morbidity". Potential abdominal complications include bulging ("pooching"), a hernia, and significant loss of core muscle strength.
3) the patient must be happy with the results in terms of recovery, return to normal activity and cosmesis.
This article addresses number 2. Ideally, other than the visible scar, the patient's abdomen must recover completely from the surgery, have an aesthetic contour, and suffer no long-term problems to be deemed a full success. Merely preserving abdominal muscle will not guarantee full recovery. It does not matter how much muscle is saved if the nerves supplying it have all been cut. A muscle without a healthy nerve supply will lose it's tone, strength and function. If the DIEP surgeon does not take great care to identify and preserve the majority of the nerves supplying the abdominal muscle then the benefits of the DIEP flap procedure are potentially lost, and the risk of abdominal complications, especially an unsightly bulge, increases.