The radioanatomy of endonasal flap coverage of skull base defects: A tool for preoperative planning.

OBJECTIVES/HYPOTHESIS: To develop a tool for the calculation of surgical skull base defects and endonasal flap dimensions on preoperative computed tomography (CT) to aid surgical planning. STUDY DESIGN: Case series. METHODS: A literature search was conducted to identify all endonasal flaps. There were five basic models identified. These are the nasoseptal flap, anterior lateral nasal wall flap, bipedicled anterior septal flap, posterior pedicled inferior turbinate flap, and middle turbinate flap. Publications on the radioanatomy of endonasal flaps and surgical skull base defects were also identified. Using these descriptions as a reference, 38 radioanatomic variables were measured on CT scans obtained from 60 preoperative endonasal skull base surgery patients. These were then used to model endonasal flap coverage of six defects: transfrontal, transcribriform, transplanar, transsellar, transsphenoidal, and transclival. RESULTS: The nasoseptal provides adequate coverage for most defects. The posteriorly pedicled inferior turbinate flap is a good alternative, and provides better coverage of posterior skull base defects. The anterior lateral nasal wall flap is the best choice for transfrontal defects. The middle turbinate flap and bipedicled anterior septal flaps provide secondary options when larger flaps are not available. CONCLUSIONS: We have developed a simple tool for the calculation of endonasal flap coverage of surgical skull base defects on preoperative CT scans. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1287-1293, 2018.

The arterial supply of the nasal cavity.

With the development of endonasal flaps, an understanding of the arterial anatomy of the nasal cavity has become increasingly important for clinicians. Despite this, there is a lack of current, accurate overviews in the literature. We have used both endoscopic and gross dissection of six fresh frozen cadaveric heads, alongside a literature review, to produce a comprehensive description of the anatomy. Four heads had their arterial systems injected with red latex. Three injected and two uninjected heads were dissected endoscopically, to provide a total of seven sides. The fourth injected head was hemisected for gross examination. The arterial systems were dissected and examined. The posterior septal artery was found to enter the nasal cavity from the sphenopalatine foramen in five sides. It bifurcated on the sphenoid rostrum in seven sides with a bifurcation lateral to the sphenoid ostium occurring in five sides and a medial bifurcation in two sides. The posterior septal artery supplied Kiesselbach's plexus on the nasal septum along with the greater palatine artery and septal branches of the superior labial and anterior ethmoidal arteries. The posterior lateral nasal artery arose from the sphenopalatine foramen in five sides to supply the lateral wall. The lateral wall branch of the anterior ethmoidal and the anterior lateral nasal artery anastomosed at the head of the inferior turbinate. These findings were mostly consistent with the current literature. We have produced a detailed and up-to-date description and diagram of the arterial supply to the nasal cavity, which may be of use to clinicians, anatomists and students.