Endoscopic endonasal transpterygoid approaches: Anatomical landmarks for planning the surgical corridor

Objectives/Hypothesis: Endoscopic endonasal transpterygoid approaches (EETA) use the pneumatization of the sinonasal corridor to control lesions of the middle and posterior skull base. These surgical areas are complex and the required surgical corridors are difficult to predict. Aim: Define anatomical landmarks for the preoperative planning of EETAs. Study design: Anatomical study. Methods: We reviewed images from high-resolution maxillofacial CT scans with (0.6-mm axial slice acquisition). Cephalometric measurements were obtained using Kodak Carestream Image Software (Rochester, NY). Results: Average distance from midline to the vidian canal was 12.78 mm (range 9.4-15.8 mm). Average horizontal distance from the vidian canal to the foramen rotundum was 5.6 mm (range 2.8-11.5 mm). Average vertical distance from the vidian canal to the foramen rotundum was 6.22 mm (range 4.3-9.3 mm). These landmarks are consequential during the preoperative planning of the surgical corridor. To facilitate communication, we classified EETAs as: A) Partial removal of the pterygoid plates (transposition of temporo-parietal fascia); B) removal of anteromedial aspect of the pterygoid process (lesions involving the lateral recess of the sphenoid sinus); C) involves dissecting the vidian nerve to control the petrous ICA and removing the pterygoid plates base to reach the petrous apex, Meckel's cave, or cavernous sinus; D) variable removal of the pterygoid plates to access the infratemporal fossa; and E) removal of pterygoid process and medial third of the Eustachian tube to expose the nasopharynx. Conclusions: Our novel classification and landmarks system helps to understand the anatomy of this complex area and to accurately plan the EETA.