Objective: Tumors arising from the upper parapharyngeal space (UPPS) may have intimate relationships with the internal carotid artery (ICA) and the internal jugular vein (IJV). The significance of the ICA in UPPS has been sufficiently articulated, whereas the relevance of the IJV has not been addressed. This study aimed to assess the anatomical variations of the IJV within the UPPS, and to explore its implications for surgical procedures. Methods: An endoscopic dissection of the IJV was performed on 10 cadaveric specimens. In addition, 30 patients who underwent transoral or transcervical resection of UPPS tumors were retrospectively reviewed to characterize the IJV and its relation to the tumor. Results: On the cadaveric specimens, the IJV was located at the posteromedial and posterolateral aspects of the styloid process in 13 (65%) and 7 (35%) sides, respectively. In our clinical series, the IJV was not encountered in 18 patients with pre-styloid tumors. In 12 patients harboring retro-styloid tumors, the IJV was partially (n = 5) or completely (n = 7) compressed and was displaced into the posterolateral aspect of the tumor. The IJV was injured intraoperatively in 1 patient, requiring an immediate conversion to an open transcervical corridor that allowed its exposure and ligation without difficulty. Conclusion: This study characterizes the IJV and its relationship with adjacent neurovascular structures in the UPPS, which may provide further safeguards during transoral and transcervical procedures in the UPPS.
Keywords: endonasal; internal carotid artery; internal jugular vein; transoral; upper parapharyngeal space.