2026 Proffered Presentations
S103: MORPHOMETRIC MAPPING OF THE PARAPHARYNGEAL INTERNAL CAROTID ARTERY VIA A TRANSORAL ENDOSCOPIC CORRIDOR: A CADAVERIC STUDY BASED ON A NOVEL PROPOSED MODULAR CLASSIFICATION
Gianluca L Fabozzi1; Rakhmon Egamberdiev1; Thibault Passeri1; Longgang Yu1; Maria Karampouga1; Eric W Wang2; Garret Choby2; Georgios A Zenonos1; Paul A Gardner1; Carl H Snyderman2; 1Department of Neurological Surgery, University of Pittsburgh Medical School (UPMC), Pittsburgh, Pennsylvania; 2Department of Otolaryngology, University of Pittsburgh Medical School (UPMC), Pittsburgh, Pennsylvania
Objective: The parapharyngeal internal carotid artery (ppICA) represents a key surgical landmark within the parapharyngeal space (PPS), where its deep location and close neurovascular relationships make inadvertent injury potentially catastrophic. Transoral endoscopic approach is increasingly used for styloid process resection in Eagle’s syndrome and management of PPF tumors (e.g. pleomorphic adenoma and paraganglioma). Using a novel modular subdivision of the ppICA into three surgical segments— infrapetrous or upper ppICA (UppICA), extending from its entry into the carotid canal to the stylo-muscular complex; stylo-muscular or middle ppICA (MppICA), at the level of the styloid process and stylopharyngeal diaphragm; and infra-styloid lower ppICA (LppICA), from this intersection to the most caudal point accessible transorally—we performed a systematic morphometric analysis, with emphasis on spatial relationships, surgical depth, and vascular variations.
Methods: Five cadaveric heads (10 sides) underwent endoscopic-assisted transoral dissection through a retromolar trigone approach (navigation accuracy <1 mm). Measurements were obtained at three predetermined targets: the carotid canal (CC) for the UppICA, the styloid tip intersection (STI) with MppICA, and the lowest transorally accessible point of LppICA. Morphometric parameters included transorally accessible length, distances to osseous landmarks (e.g., styloid tip and base, maxillary tuberosity, C1 and C2), surgical corridor depth, and craniocaudal extension. Variants in arterial course were classified according to Paulsen’s criteria as straight, tortuous, kinked, or coiled.
Results: The mean transorally accessible length of the ppICA was 37.34 ± 5.15 mm, with styloid-intersecting segment averaging 28.53 ± 5.21 mm (≈76% of the exposed artery) (Fig.1). Corridor depth measured 45.34 ± 4.16 mm to the CC and 29.63 ± 3.97 mm to the MppICA, selected as stable and reproducible reference points for measurement. Calculations for the LppICA were not performed, given the greater anatomical variability and less consistent exposure of the distal segment through the transoral route. Key landmark distances were styloid base to CC (16.27 ± 4.66 mm), styloid tip to CC (34.82 ± 4.74 mm), and styloid tip to MppICA (8.18 ± 2.08 mm) (Fig. 2). The MppICA lay at a mean distance of 32.88 ± 4.05 mm from the maxillary tuberosity, compared with 44.69 ± 2.77 mm from the CC (Fig. 3). Craniocaudal exposure extended from the C1 transverse process (20.07 ± 4.97 mm from MppICA; 22.68 ± 5.25 mm from CC) to C2 (20.55 ± 4.58 mm from MppICA; 35.36 ± 6.18 mm from CC). Anatomical variations occurred in 30% of sides, tortuosity in 2 cases and kinking in 1 case.
Conclusion: This cadaveric study provides a detailed morphometric characterization of the ppICA through a transoral endoscopic corridor, framed within a proposed modular classification. The styloid apparatus emerged as a critical anatomical reference, intersecting ≈76% of the surgically accessible ppICA. Quantitative data on depth, landmark relationships and craniocaudal extension establish reproducible guidance for safe dissection, while the high prevalence of vascular variants underscores the need for meticulous preoperative imaging. This work offers a first anatomical insight into a novel modular ppICA classification; however, clinical translation will require comparative evaluation of alternative surgical corridors and validation in tumor-distorted anatomy.
