Endoscopic Nasopharyngectomy Combined with a Nerve-Sparing Transpterygoid Approach: An Anatomic Study

Background Surgical treatment of nasopharyngeal tumors that extend beyond the fossa of Rosenmueller may require a transpterygoid approach to obtain oncologic margins. Clearing margins may put critical structures, such as the petrous internal carotid artery at risk. The endoscopic endonasal transpterygoid approach is a lateral extension of the traditional parasagittal corridor in the coronal plane, which provides access to the aforementioned structures. Exposure and management of the contents of the pterygopalatine fossa is crucial to successful surgery in this area. Sacrifice of the Vidian and descending palatine nerves significantly improves lateral and superior access but does result in morbidity. Our study examines the anatomic limitations of endoscopic nasopharyngectomy combined with a nerve-sparing transpterygoid approach to address bony margins around foramen lacerum, the petrous internal carotid artery, and the eustachian tube.

Methods Eight transnasal endoscopic nasopharyngectomies were performed in fresh cadaveric specimens with attempts to preserve all neurovascular structures including the Vidian and descending palatine nerves. The dissection was performed using a binarial, extended, endoscopic endonasal approach using 0- and 45-degree endoscopes. Exposure was obtained with endoscopic visualization and was then confirmed with Stryker Nav3 image guidance software (IGS).

Results Successful en bloc nasopharyngectomy combined with a nerve-sparing transpterygoid approach was achieved in all specimens with successful preservation of the descending palatine and Vidian nerves. This approach provided exposure of foramen lacerum, the petrous carotid and foramen ovale, as well as all segments of the cartilaginous and bony eustachian tube. Meckel’s cave, the parapharyngeal carotid, and infratemporal fossa were also identified but not dissected. Endoscopic exposure was confirmed with IGS in all cases. While sacrifice of the Vidian or descending palatine nerves was not required, both nerves were completely skeletonized to obtain adequate exposure. There was no inadvertent injury of the internal carotid artery.

Conclusion Endoscopic nasopharyngectomy combined with a nerve-sparing transpterygoid approach provides safe exposure to the bony eustachian tube with preservation of the petrous and parapharyngeal segments of the internal carotid artery without sacrificing the Vidian or greater palatine nerves. This technique allows for an en bloc resection of the cartilaginous eustachian tube and nasopharyngeal contents while potentially avoiding the morbidity of Vidian and descending palatine nerve transection. In the future, clinical studies are needed to validate the benefits of this technique.