Endoscopic Transoral Nasopharyngectomy

Background: In the past decade, minimal access endoscopic endonasal approaches (EEA) to the nasopharynx have been developed. For large nasopharyngeal tumors extending below the palatal plane and laterally beyond the pterygoid musculature, maxillary swing, and Fisch’s type C infratemporal fossa approaches are necessary. The purpose of this study is to evaluate the possibility of achieving an endoscopic transoral nasopharyngectomy (ETON) for resection of large nasopharyngeal lesions as a natural orifice alternative to open approaches.

Study Design: Present study is a cadaveric study with clinical correlate.

Methods: ETON was completed in a fresh cadaveric specimen under endoscopic guidance. The resection extended superiorly to the sphenoid sinus, inferiorly to the same axial plane as the tongue, laterally to the mandible and posteriorly to the prevertebral musculature. Surgical freedom and angles of attack were also measured at the first genu, and the second genu of the internal carotid artery (ICA).

Results: The resection can be completed in two steps. First, parapharyngeal space (PPS) dissection with or without infratemporal fossa (ITF) dissection. An incision is made 2 cm from the maxillary alveolar ridge along the hard palate and carried down to the lateral floor of mouth. Exposure and resection of the posterior hard palate, maxillary tuberosity, pterygoid hamulus, pterygoid plates, and prestyloid PPS was performed followed by identification of the parapharyngeal ICA with subsequent ITF dissection. Second, eustachian tube (ET) removal and sphenoidotomy. The ET is identified superomedially and dissected off the skull base followed by the removal of petrous bone and exposure of petrous ICA with subsequent sphenoidotomy. Full exposure of the parapharyngeal and petrous ICA was achieved. The anterior and posterior genu were accurately identified with accurate dissection and identification of surrounding neurovascular structures. Surgical freedom (cm²) at the first genu and second genu were 20.54 and 26.4 cm², respectively. The angles of attack (degrees) for the first genu were 65.7 and 29.1 degrees on the axial and sagittal planes, respectively. The angles of attack for the second genu were 78.25 and 29.61 degrees on the axial and sagittal planes, respectively. A patient with recurrent nasopharyngeal carcinoma (rNPC) with apparent recurrence surrounding the ICA at the skull base was managed with a pure transoral approach. PPS dissection without ITF dissection was undertaken. The parapharyngeal ICA was successfully identified and followed to the skull base. The tumor was biopsied and the diagnosis was confirmed.

Discussion: ETON is a feasible technique. Resection can extend laterally to the mandible and inferiorly to the level of the tongue, or inclusively lower. ETON may be indicated for the management of nasopharyngeal tumors that extend laterally into ITF and extend inferiorly below the palatal plane. ETON also provides adequate visualization and manipulation of the ICA, as well as accurate dissection of surrounding tissues, thus, making it an attractive approach for tumors in direct contact with the ICA.