Endoscopic endonasal nasopharyngectomy: tensor veli palatine muscle as a landmark for the parapharyngeal internal carotid artery.

Background: Endoscopic endonasal nasopharyngectomy(EEN) can be a promising option for select patients with recurrent nasopharyngeal carcinoma, but serious complications can occur in terms of parapharyngeal internal carotid artery (PPICA) injury. Several landmarks have been proposed for locating the PPICA. In this study, we investigated the spatial relationship between the tensor veli palatini (TVP) muscle and the PPICA in a cadaveric model.

Methods: Seven fresh cadaver heads were available for anatomic study. Eustachian tube and the levator veli palatine (LVP) muscle were partially sacrificed or truncated to maximize the surgical field, and the TVP muscle was carefully preserved. Complete dissection was defined as when the PPICA could be visualized. We then measured the distance between the posterior margin of the TVP muscle and PPICA (z-axis), and the distance from the midline of the nasopharynx to the PPICA (x-axis).

Results: Thirteen sides of the PPICA were successfully identified. The mean distance between the posterior margin of the TVP to the PPICA (z) was 20.3 mm (range, 12 to 28 mm), and the mean distance between the midline of the nasopharynx to the PPICA (x) was 19.6 mm (range, 15 to 24 mm).

Conclusion: The PPICA was located in the same sagittal plane as the TVP muscle during dissection posteriorly. The PPICA appeared to lie around 2 cm laterally from the midline at around 2 cm in depth from the posterior margin of the TVP muscle. However, the exact position of the PPICA should be assessed using preoperative magnetic resonance imaging and intraoperative image-guided systems.