The microvascular supply of locoregional flaps in head and neck reconstruction: revealing the anatomical bases for selected clinical applications

© 2015 Dr. Richard James McNicol RossReconstruction of defects of the head and neck remains a challenge to even the most experienced reconstructive surgeon. Tissue loss or destruction may follow ablation of tumour, trauma or infection as well as congenital anomalies. Efforts to provide basic functions such as oral continence, corneal protection, social interaction and a robust barrier from the environment are subject to the constant battle to provide well vascularised, resilient yet pliable tissue as inconspicuously as possible. To achieve success, the surgeon must possess a detailed understanding of the microvascular anatomy of their chosen reconstructive technique. To this end, the microvascular anatomy of three emerging techniques was explored using ex vivo injection studies, radiographic imaging and clinical correlation. Ex vivo cadaveric dissection studies followed non-destructive contrast-enhanced computer tomographic angiography. Further, in vivo computer tomographic angiography was used to correlate ex vivo findings with clinical reality. Finally, a brief pilot series of clinical cases demonstrated clinical utility and implementation of translational research. The superior thyroid artery perforator flap presents a new technique exploiting the often redundant anterior cervical skin as a locoregional, pedicled flap amenable for reconstruction of lateral and lower facial defects. The arterial and venous circulation of the superior thyroid perforator flap was examined in a cadaveric dissection study, plus in vivo computer tomographic angiography and finally in a brief pilot series of clinical cases. The arterial supply was consistently found to be a direct cutaneous perforator from the superior thyroid artery, with venous drainage via the anterior jugular veins. The supraclavicular flap was investigated to further clarify the microcirculation of this technique, previously neglected due to concerns of poor reliability. This study utilised cadaveric angiographic techniques to describe the pattern of microcirculation. Here, a series of small calibre choke anastomoses and reliance on interperforator and retrograde flow was found to influence the reliability of this flap. Consequently, we recommend strict adherence to maximal flap dimensions and consideration to include multiple venous anastomoses in order to reduce the chance of flap necrosis. Further investigations into microvascular communications in head and neck reconstruction focussed on the most complex surgical endeavours in the region- vascularised tissue allotransplantation. This field remains in experimental stages with heavy reliance on preoperative cadaveric studies to better prepare and understand the surgical requirements. Further to the technical difficulties, total flap failure would rendering the patient with no facial integument or skeletal structure and exposure of vital deep structures, bringing with it a real risk of death. This study used computer tomographic angiography to provide increased detail of the communications of the facial artery within the three-dimensional allotransplant. The facial artery was found to perfuse the ipsilateral and contralateral facial tissue including Le Fort III segment via a network of deep-to-superficial and cross-midline anastomoses. Whilst this suggests that a single unilateral facial artery may be sufficient to supply such an osteocutaneous allotransplant, risk aversion should prevail and the authors recommend including additional anastomoses to reduce the chance of potentially fatal vascular compromise of the allograft. This work provides advancement in the current understanding of head and neck microvasculature and targets three potentially valuable techniques to illustrate how this understanding can improve patient outcomes