Tuesday, November 18, 2008

Avoiding Denervation of Abdominal Muscles during DIEP Flap Breast Reconstruction Surgery

The following interesting article was published in the "Plastic and Reconstructive Surgery" journal this month.....

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.


Here's my take....

The long and the short of it is that for DIEP flap surgery to be considered successful several things need to happen (in my opinion):

1) the tissue (flap) transferred to the chest to create the new breast must survive. ie the new breast must live. Obvious.
2) the patient must not suffer any ill-effects from removal of the tissue ("flap") from the abdomen. This is what we call in the trade "donor-site morbidity". Abdominal bulging, hernia and significant muscle strength loss fall in this category.
3) the patient must be happy.

Number 1 is obvious.

This article addresses number 2. Ideally, other than the scar, the patient's abdomen must recover completely from the surgery and suffer no long-term problems for the surgery to be deemed a full success.

It does not matter how much muscle is left behind 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 are potentially lost.

I feel it is important for me to make an additional point..... I'm going to take it for granted that you have chosen an experienced DIEP flap surgeon. I have heard of some patients (indeed some of mine too) entering the consultation with their DIEP flap surgeon having already decided they will be getting a DIEP flap and nothing else. This is a dangerous game to play and I'm going to explain why.

I'd like to think that most breast reconstruction surgeons would spend the required time with their patient discussing the differences between saving ALL the abdominal muscle (a DIEP flap) and having to sacrifice a very small amount (a muscle-sparing type 2 free TRAM).

The truth is this.... in some (very few) instances, patient's do not have the appropriate anatomy to allow for a DIEP flap. Though this happens rarely in our practice, it does still happen on occasion. Trying to "force" a DIEP flap out of a patient who does not have favorable anatomy requires more muscle dissection and will significantly increase the risk of nerve damage to the abdominal muscle. The potential resulting loss of tone, strength and function will place the patient in a much worse position than if she'd had a muscle-sparing type 2 free TRAM flap to begin with (postage-stamp sized piece of muscle sacrificed).

Please do not be adamant going in to the consult about which procedure you're to receive. As long as you have chosen an experienced microsurgeon specializing in these procedures chances are that you will indeed get a DIEP flap. BUT, your anatomy is the deciding factor. Your surgeon didn't give that to you, he just has to work with it.

Dr C


Dr Chrysopoulo is a board certified breast reconstruction surgeon specializing in DIEP flap breast reconstruction surgery. He and his partners perform over 350 DIEP flap procedures each year with a success rate of over 99%. PRMA Plastic Surgery, San Antonio, Texas. Toll Free: (800) 692-5565. Keep up to date with the latest breast reconstruction news by following Dr Chrysopoulo's Breast Cancer Reconstruction Blog.

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