The mandibular strut and inferior petrous carotid triangle as key landmarks for endoscopic endonasal localization of the parapharyngeal internal carotid artery

OBJECTIVE: The objective was to define anatomical landmarks for the parapharyngeal segment of the internal carotid artery (ICA) relevant to the endoscopic endonasal approach (EEA). METHODS: A technique was developed through laboratory investigation and demonstrated in a nasopharyngectomy. RESULTS: A transpterygoid approach revealed the foramen lacerum, the parasellar and paraclival ICA was exposed, and the lingual process removed. Drilling proceeded through the mandibular strut and adjacent petrous base along the inferolateral surface of the horizontal petrous ICA (hpICA) up to the vertical petrous ICA (vpICA). The medial jugular tubercle was drilled, and the eustachian tube was disconnected and removed. Dissection was performed from superior to inferior using the vpICA to locate the carotid foramen and parapharyngeal ICA (ppICA). The inferior petrous carotid (IPC) triangle was identified and delineated by the ventral hpICA, vpICA, and the line connecting the carotid foramen to the lacerum cartilage. Its importance lies in providing access for an anteroinferior petrosectomy, which is obstructed by the hpICA in an open approach, while its inferior apex marks the depth of the ppICA and enables safer parapharyngeal space dissection. CONCLUSIONS: The mandibular strut and IPC triangle serve as valuable landmarks for tracing the petrous ICA, facilitating reliable craniocaudal localization of the ppICA during EEA.