Taylor Gi

Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall.

Previous descriptions of the thoracolumbar spinal nerves innervating the anterior abdominal wall have been inconsistent. With modern surgical and anesthetic techniques that involve or may damage these nerves, an improved understanding of the precise course and variability of this anatomy has become increasingly important. The course of the nerves of the anterior abdominal is described based on a thorough cadaveric study and review of the literature. Twenty human cadaveric hemi‐abdominal walls were dissected to map the course of the nerves of the anterior abdominal wall. Dissection included a comprehensive tracing of nerves and their branches from their origins in five specimens. The branching pattern and course of all nerves identified were described. All thoracolumbar nerves that innervate the anterior abdominal wall were found to travel as multiple mixed segmental nerves, which branch and communicate widely within the transversus abdominis plane (TAP). This communication may occur at multiple locations, including large branch communications anterolaterally (intercostal plexus), and in plexuses that run with the deep circumflex iliac artery (DCIA) (TAP plexus) and the deep inferior epigastric artery (DIEA) (rectus sheath plexus). Rectus abdominis muscle is innervated by segments T6‐L1, with a constant branch from L1. The umbilicus is always innervated by a branch of T10. As such, identification or damage to individual nerves in the TAP or within rectus sheath is unlikely to involve single segmental nerves. An understanding of this anatomy may contribute to explaining clinical outcomes and preventing complications, following TAP blocks for anesthesia and DIEA perforator flaps for breast reconstruction. Clin. Anat. 21:325–333, 2008.

Establishing the case for CT angiography in the preoperative imaging of abdominal wall perforators

Preoperative imaging of the donor site vasculature for deep inferior epigastric artery (DIEA) perforator flaps and other abdominal wall reconstructive flaps has become more commonplace. Abdominal wall computed tomography angiography (CTA) has been described as the most accurate and reproducible modality available for demonstrating the location, size, and course of individual perforators. We drew on our experience of 75 consecutive patients planned for DIEA‐based flap surgery undertaking CTA at a single institution. Seven of these cases have been reported to highlight the utility of CTA for preoperative planning, emphasizing the unique information supplied by CTA that may influence operative outcome. Among all cases that underwent preoperative imaging with CTA, there was 100% flap survival, with no partial or complete flap necrosis. We found that in three of the cases described, the choice of operation was necessarily selected based on CTA findings (DIEA perforator flap, transverse rectus abdominis myocutaneous flap, and superficial superior epigastric artery flap). In addition, three cases demonstrate that CTA findings may dictate the decision to operate at all, and one case demonstrates the utility of CTA for evaluating the entire abdominal contents for comorbid conditions. Our experience with CTA for abdominal wall perforator mapping has been highly beneficial. CTA may guide operative technique and improve perforator selection in uncomplicated cases, and in difficult cases it can guide the most appropriate operation or indeed if an operation is appropriate at all. This is particularly the case in the setting of comorbidities or previous abdominal surgery.

Developments in perforator imaging for the anterolateral thigh flap: CT angiography and CT‐guided stereotaxy

Introduction: The anterolateral thigh flap is an increasingly popular reconstructive option despite uncertainty in its perforator anatomy. Perforators are not always present, vary in size and intramuscular course, and have variable cutaneous courses and supply. As such, preoperative imaging has become favored. Methods: The current study describes the preliminary use of two new modalities for preoperative imaging: computed tomography (CT) Angiography and CT‐guided stereotaxy. These have been utilized in the preoperative imaging of two patients undergoing ALT flap reconstruction. Each patient underwent each of these techniques combined with Doppler ultrasound, the previous standard modality. The size, location, and course of perforators were explored and compared with operative findings. Results: Both techniques are technically feasible, highly accurate, and provide more information to the surgeon than ultrasound. Conclusion: CT Angiography and CT‐guided stereotaxy are useful adjuncts to Doppler ultrasound for imaging perforators prior to ALT flaps. A larger study is suggested to quantify the accuracy of these techniques.

Reviewing the vascular supply of the anterior abdominal wall: Redefining anatomy for increasingly refined surgery

The abdominal wall integument is becoming the standard donor tissue for postmastectomy breast reconstruction, with its vascular supply of key importance to the reconstructive surgeon. Refinements in tissue transfer, from pedicled to free flaps and musculocutaneous to perforator flaps, have required increasing understanding of finer levels of this vascular anatomy. The widespread utilization of the deep inferior epigastric artery (DIEA) perforator flap, particularly for breast reconstruction, has rekindled clinical interest in further levels of anatomical detail, in particular the location and course of the musculocutaneous perforators of the DIEA. Advances in operative techniques, and anatomical and imaging technologies, have facilitated an increase in this understanding. The current review comprises an appraisal of both the anatomical and clinical literature, with a view to highlighting the key anatomical features of the abdominal wall vasculature as related to reconstructive flaps. Clin. Anat. 21:89–98, 2008.

The cutaneous course of deep inferior epigastric perforators: implications for flap thinning.

BACKGROUND The deep inferior epigastric artery (DIEA) perforator flap is frequently used for autologous breast reconstruction following mastectomy. Thinning of the flap is often performed to debulk the flap of excess fatty tissue, such as in partial mastectomy defects. Thinning may disrupt the blood supply to the flap and compromise viability, however adequate guidelines for thinning are lacking from the literature. METHODS Clinical and anatomical studies were concurrently undertaken to explore the cutaneous course of perforators as a guide to flap thinning. Twenty consecutive patients undergoing DIEA perforator flap breast reconstruction underwent preoperative computerised tomography angiography (CTA), and a cadaveric study was also undertaken, in which six fresh, whole abdominal walls underwent CTA. All perforators greater than 2 mm were analysed for their cutaneous course. RESULTS In all cases, perforators emerged from the anterior rectus sheath and traversed an oblique, but direct course through the deep layer of adipose tissue, before reaching Scarpas fascia. Branching of perforators occurred in two planes of the superficial adipose layer: just superficial to Scarpas fascia (the fascial plexus) and in the subdermal plexus. CONCLUSION Thinning of DIEA perforator flaps can only be performed safely deep to Scarpas fascia. Thinning performed superficial to Scarpas fascia threatens the intrinsic blood supply to the flap.

True and 'choke' anastomoses between perforator angiosomes: part II. dynamic thermographic identification.

Background: Cadaveric studies have revealed that cutaneous perforators are linked by either reduced-caliber “choke” arteries, or by vessels without change in caliber, the true anastomoses. These true anastomotic vessels are often found in parallel with the cutaneous nerves and accompanying veins, and are associated both experimentally and clinically with larger areas of flap survival. The Doppler probe and computed tomographic angiography are already used preoperatively to determine perforator locations but currently cannot reveal the type of anastomotic connections. Methods: Thermal images were taken in a previously described fashion and compared with both computed tomographic angiographic studies where available and with cadaveric angiographic studies previously performed by the authors’ laboratory. Results: Perforators larger than 1 mm were accurately localized by thermography when compared with computed tomographic angiography. Perforator angiosome rewarming closely approximated a log-based line of best fit. Interperforator zones were variable in their rewarming and correlated with known anatomical patterns of true and choke anastomoses between perforator angiosomes. Conclusions: Thermography now offers a new modality with which to bridge the gap not only by identifying the perforator “hot spots” but also by the robustness of their interconnections. The pattern of these interconnections seen on thermographic imaging has in turn been found to match those seen in the authors’ cadaveric studies.

Stereotactic image‐guided navigation in the preoperative imaging of perforators for DIEP flap breast reconstruction

Preoperative imaging is sought prior to DIEA (Deep Inferior Epigastric Artery) perforator flaps due to the potential for maximizing operative success and minimizing operative complications. Recent advances include the use of computed tomography (CT) angiography (CTA) and magnetic resonance angiography. Image‐guided stereotactic surgery is a recent technique that has been used with success in several fields of surgery. The variability of perforator anatomy makes DIEA perforator flap surgery a suitable candidate for such technology, but as yet this has not been described. A study was undertaken to determine the feasibility of CT‐guided stereotaxy technique in DIEA perforator flap surgery and to compare findings with both conventional CTA and operative findings. Five consecutive patients planned for an elective DIEA perforator flap were recruited. Each patient underwent preoperative imaging of the anterior abdominal wall vasculature with both conventional CTA and CT‐guided stereotactic imaging. Imaging findings were compared to operative findings. In all cases, all the major perforators were accurately localized with stereotactic imaging and with conventional CTA. Stereotactic navigation demonstrated a slightly better (nonsignificant) correlation with perforator location than conventional CTA. As such, CT‐guided stereotactic imaging is an accurate method for the preoperative planning of DIEA perforator flaps, providing additional and potentially more accurate data to conventional CTA. With no additional scanning required, the method described in this paper allows the combined use of both methods for preoperative planning.

Vascularized Lymph Node Transfer: A Review of the Current Evidence.

Summary: Over the past decade, lymph node transfer has rapidly gained popularity among plastic surgeons for the treatment of chronic lymphedema because of the initial promising results and its unique technical advantages compared with the other reconstructive options. However, its functional mechanism is still a matter of great debate, and some concerning reports have emerged regarding the safety of this procedure in patients with chronic lymphedema. The authors review the literature on the experimental and clinical evidence for lymph node transfer, discuss its proposed functional mechanisms, review the potential risk of iatrogenic lymphedema following this procedure, and discuss the suggested strategies to avoid this complication.

Understanding the three-dimensional anatomy of the superficial lymphatics of the limbs.

Background: There are minimal data in the current literature regarding the depth of the superficial lymphatic collectors of the limbs in relation to the various subcutaneous tissue layers. Methods: Injection, microdissection, radiographic, and histologic studies of the superficial lymphatics and the subcutaneous tissues of 32 limbs from 15 human cadavers were performed. Results: Five layers were consistently identified in the integument of all the upper and lower limb specimens: (1) skin, (2) subcutaneous fat, (3) superficial fascia, (4) loose areolar tissue, and (5) deep fascia. Layer 2 was further divided into superficial (2a) and deep (2c) compartments by a thin, transparent, horizontal septum (layer 2b). The main superficial veins and the superficial nerves coursed in layer 4. The lymphatic collectors were found at layer 2c and layer 4. Conclusions: The use of consistent nomenclature to describe the subcutaneous tissue layers facilitates a greater understanding and discussion of the anatomy. In lymphovenous anastomosis for the treatment of lymphedema, indocyanine green lymphography is an unreliable method for identification of the superficial collectors of the thigh. The medial proximal leg, the dorsum of the wrist over the anatomical snuffbox, and the volar proximal forearm provide suitable areas for locating superficial collectors with nearby matching size veins. In vertical medial thigh lift, choosing a dissection plane superficial to the great saphenous vein is unlikely to preserve the collectors of the ventromedial bundle.

The Evolution of Free Vascularized Bone Transfer: A 40-Year Experience.

Background: The first successful free vascularized bone flap was performed on June 1, 1974 (and reported in 1975), using the fibula. This was followed by the iliac crest based on the superficial circumflex iliac artery in 1975 and then the deep circumflex iliac artery in 1978. Methods: A total of 384 transfers using fibula (n = 198), iliac crest (n = 180), radius (n = 4), rib (n = 1), and metatarsal (n = 1) were used between June of 1974 and June of 2014 for reconstruction of the mandible (n = 267), maxilla (n = 20), clavicle (n = 1), humerus (n = 8), radius and ulna (n = 21), carpus (n = 3), pelvis (n = 2), femur (n = 11), tibia (n = 47), and foot bones (n = 4). Indications were tumor ablation (n = 286), trauma (n = 84), osteomyelitis (n = 2), and the congenital deformities hemifacial microsomia (n = 2) and pseudarthrosis of the tibia (n = 9) and ulna (n = 1). Results: Successful transfer was achieved in 95 percent of patients. Union varied with the recipient bone, from 6 to 8 weeks in the jaw, 2 to 3 months in the upper limb, and 3 to 4 months in the femur and tibia. Union was fastest with iliac crest. The fibula provided easier dissection; it could be raised on either peroneal or anterior tibial vessels; the skin flap could be designed distally; it could be placed centrally in the medullary cavity of long bones; and hairline stress fracture in the lower limb frequently preceded rapid subperiosteal hypertrophy. The fibula lacks sufficient height for osseointegration, whereas iliac crest is ideal. Osteotomies of either bone are possible to straighten or increase curvature. Conclusions: The fibula is best for long bone or angle-to-angle jaw reconstruction, especially in edentulous patients. Iliac crest is best for hemimandible, curved bones (pelvis, carpus, and metacarpus), and as an alternative for short, straight, 6- to 8-cm-long bone defects.