Warren M. Rozen

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.

Preoperative imaging for DIEA perforator flaps: a comparative study of computed tomographic angiography and Doppler ultrasound.

BACKGROUND Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. METHODS Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. RESULTS Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. CONCLUSION Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.Background: Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. Methods: Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. Results: Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. Conclusion: Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.

DOES THE PREOPERATIVE IMAGING OF PERFORATORS WITH CT ANGIOGRAPHY IMPROVE OPERATIVE OUTCOMES IN BREAST RECONSTRUCTION

Background: Breast reconstruction is increasingly performed with the use of the abdominal wall donor site, with potential complications including donor site morbidity and impaired flap viability. As a tool for selecting the optimal perforators which will ultimately supply the flap, preoperative imaging with computed tomography angiography (CTA) has become increasingly popular. Potential benefits include reduced intramuscular dissection, with faster and safer dissection, reduced donor site morbidity and improved flap vascularity and survival. Despite the potential for improvements in operative outcome, any benefits are yet to be established. Methods: A cohort study of 104 breast reconstructions in 88 patients was conducted. All patients underwent breast reconstruction based on an abdominal wall free flap. Of these, 40 patients undergoing preoperative imaging with CTA and 48 patients not undergoing CTA were included, with all CTAs undertaken at a single institution. Length of operation, length of stay, and operative complications were assessed. An evaluation of operative stress was achieved with the use of visual analogue scales (VAS) administered to the surgeons. Results: The use of CTA was associated with decreased operating time (mean: 77 min for bilateral cases), significantly decreased complications related to flap viability (particularly partial flap loss), and a statistically significant reduction in donor site morbidity. Psychometric testing of surgeons revealed a statistically significant decrease in operative stress (41% decrease) with the use of preoperative CTA. Conclusion: The use of CTA for preoperative imaging in breast reconstruction is associated with improved operative outcomes.

Spread of injectate after ultrasound-guided subcostal transversus abdominis plane block: a cadaveric study

Ultrasound‐guided transversus abdominis plane (TAP) block can be performed using a subcostal technique. This technique was simulated using dye injection in cadavers in order to determine segmental nerve involvement and spread of injectate using either single or multiple‐injection techniques. Dye most commonly spread to affect T9 and T10 nerves with the single injection technique and T9, T10 and T11 with multiple injections. The median (IQR [range]) spread of dye was 60 (36–63 [32–78]) cm2 using the single‐injection technique and 90 (85–96 [72–136]) cm2, in the multiple‐injection technique, and this difference was statistically significant (p = 0.003). These results indicate that ultrasound‐guided subcostal TAP block will involve nerve roots T9, T10 and T11 and that a multiple‐injection technique may block more segmental nerves and increase spread of injectate.

Abdominal Wall CT Angiography: A Detailed Account of a Newly Established Preoperative Imaging Technique

Institutional review board approval was obtained for this study, and all patients gave written informed consent. Autologous surgical breast reconstruction with use of abdominal wall donor flaps based on the deep inferior epigastric artery (DIEA) and one or more of its anterior musculocutaneous perforating branches (DIEA perforator flap) is being used with increasing frequency instead of breast reconstruction with use of traditional transverse rectus abdominus musculocutaneous and modified muscle-sparing flaps. Preoperative mapping of the DIEA perforators with abdominal wall computed tomographic (CT) angiography may improve patient care by providing the surgeon with additional information that will lead to optimization of the surgical technique, shorter procedure time, and reduction in the frequency of surgical complications. The branching patterns of the DIEA, the segmental anatomy of the anterior adipocutaneous perforating branches of the DIEA, and the importance of these features in pre- and intraoperative surgical planning necessitate a different approach to abdominal wall CT angiography than that used with other abdominal CT angiographic techniques. In abdominal wall CT angiography, the common femoral artery is used as the bolus trigger, CT scanning is performed in the caudocranial direction, the automatic exposure control feature is disabled, a scaled grid overlay tool is used to present information to the surgeons, and radiation dose is minimized (average dose, 6 mSv). The anatomic accuracy of abdominal wall CT angiography has been investigated in cadaveric and surgical studies, with sensitivity of 96%-100% and specificity of 95%-100%. This detailed description will allow other radiologists and surgeons interested in free DIEP flap surgery to incorporate this useful tool into their practice.

Emerging Applications of Bedside 3D Printing in Plastic Surgery

Modern imaging techniques are an essential component of preoperative planning in plastic and reconstructive surgery. However, conventional modalities, including three-dimensional (3D) reconstructions, are limited by their representation on 2D workstations. 3D printing, also known as rapid prototyping or additive manufacturing, was once the province of industry to fabricate models from a computer-aided design (CAD) in a layer-by-layer manner. The early adopters in clinical practice have embraced the medical imaging-guided 3D-printed biomodels for their ability to provide tactile feedback and a superior appreciation of visuospatial relationship between anatomical structures. With increasing accessibility, investigators are able to convert standard imaging data into a CAD file using various 3D reconstruction softwares and ultimately fabricate 3D models using 3D printing techniques, such as stereolithography, multijet modeling, selective laser sintering, binder jet technique, and fused deposition modeling. However, many clinicians have questioned whether the cost-to-benefit ratio justifies its ongoing use. The cost and size of 3D printers have rapidly decreased over the past decade in parallel with the expiration of key 3D printing patents. Significant improvements in clinical imaging and user-friendly 3D software have permitted computer-aided 3D modeling of anatomical structures and implants without outsourcing in many cases. These developments offer immense potential for the application of 3D printing at the bedside for a variety of clinical applications. In this review, existing uses of 3D printing in plastic surgery practice spanning the spectrum from templates for facial transplantation surgery through to the formation of bespoke craniofacial implants to optimize post-operative esthetics are described. Furthermore, we discuss the potential of 3D printing to become an essential office-based tool in plastic surgery to assist in preoperative planning, developing intraoperative guidance tools, teaching patients and surgical trainees, and producing patient-specific prosthetics in everyday surgical practice.

Advances in the pre-operative planning of deep inferior epigastric artery perforator flaps: magnetic resonance angiography.

Imaging of the abdominal wall vasculature prior to deep inferior epigastric artery (DIEA) perforator (DIEP) flaps has been shown to significantly improve surgical outcomes. Although computed tomography angiography (CTA) has been shown to be highly accurate, it is associated with radiation exposure, and as such modalities without radiation exposure have been sought. Magnetic resonance angiography (MRA) has been proposed as such an option. We conducted a pilot study comparing MRA with CTA and with operative findings in six consecutive patients undergoing DIEP flaps for breast reconstruction. The DIEA, superficial inferior epigastric artery (SIEA) and perforators were all assessed with each modality. We found that the DIEA and SIEA were accurately imaged with both CTA and MRA, but that while MRA could identify some major perforators, CTA was more accurate than MRA for perforator mapping. As such, while MRA does have a role in the imaging of DIEA perforators, CTA is still the preferred modality. On the basis of these findings, a larger study into the role for MRA in this setting is warranted.

The arterial anatomy of the Achilles tendon: Anatomical study and clinical implications

The Achilles tendon is the most frequently ruptured tendon in the lower limb and accounts for almost 20% of all large tendon injuries. Despite numerous published studies describing its blood supply, there has been no uniformity in describing its topography. The current study comprises a detailed anatomical study of both the intrinsic and extrinsic arterial supply of the Achilles tendon, providing the detail sought from studies calling for improved planning of surgical procedures where damage to the vascularity of the Achilles tendon is likely. A dissection, microdissection, histological, and angiographic study was undertaken on 20 cadaveric lower limbs from 16 fresh and four embalmed cadavers. The Achilles tendon is supplied by two arteries, the posterior tibial and peroneal arteries. Three vascular territories were identified, with the midsection supplied by the peroneal artery, and the proximal and distal sections supplied by the posterior tibial artery. The midsection of the Achilles tendon was markedly more hypovascular that the rest of the tendon. The Achilles tendon is at highest risk of rupture and surgical complications at its midsection. Individuals with particularly poor supply of the midsection may be at increased risk of tendon rupture, and approaches to the tendon operatively should consider the route of supply by the peroneal artery to this susceptible part of the tendon. Clin. Anat. 22:377–385, 2009.

The accuracy of computed tomographic angiography for mapping the perforators of the deep inferior epigastric artery: a blinded, prospective cohort study.

Background: The deep inferior epigastric artery perforator flap is increasingly used for autologous breast reconstruction, with low donor-site morbidity cited as a major advantage of this operation. Preoperative imaging of the donor-site vasculature is frequently used as a further means of improving operative outcome. Computed tomographic angiography has been increasingly described as a preferred imaging modality; however, its formal evaluation has not been described in a clinical setting. Methods: A prospective, single-blind, cohort study was undertaken on 60 consecutive patients for whom deep inferior epigastric artery perforator flap surgery had been planned. Patients who did not undergo the procedure during the study period were excluded, with 42 patients ultimately included in the study. All computed tomographic angiography scans were obtained at a single institution. Perforators were mapped both on angiography and intraoperatively using a grid of 4-mm squares centered on the umbilicus. Only perforators larger than 1 mm were included in the study. All imaging findings were recorded by a single operator, and all intraoperative findings were recorded by the operating surgeon. Results: Computed tomographic angiography identified 280 major perforators in 42 patients. It was highly accurate, demonstrating 279 perforators recorded accurately, with one false-positive and one false-negative. Its sensitivity for mapping perforators was thus 99.6 percent, with a positive predictive value of 99.6 percent. Conclusions: Computed tomographic angiography is highly accurate in identifying and mapping the perforators of the deep inferior epigastric artery. Its accuracy is superior to that of the previous modalities used in this role and suggests the usefulness of this technique before deep inferior epigastric artery perforator flap surgery for breast reconstruction.

Avoiding denervation of rectus abdominis in DIEP flap harvest: the importance of medial row perforators.

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.