Transnasal endoscopic medial maxillectomy as the initial oncologic approach to sinonasal neoplasms: the anatomic basis.

OBJECTIVE: To demonstrate an anatomic basis for endoscopic medial maxillectomy with excision of the lateral nasal wall to the nasal floor, including the inferior turbinate, and nasolacrimal duct. Transnasal endoscopic medial maxillectomy involves complete resection of the lateral nasal wall with boundaries that are inferior to the nasal floor; superior to the cribriform plate and fovea ethmoidalis; anterior to the anterior maxillary wall, including the nasolacrimal duct; and posterior to within 5 mm of the eustachian tube. Transnasal endoscopic medial maxillectomy provides exposure for endoscopic resection of the orbital wall, pterygopalatine fossa, pterygoid plates, nasopharynx, and anterior skull base when indicated.

DESIGN: Volumetric analysis of the maxillary sinus was performed on axial and coronal computed tomographic scans of 19 adult patients for a total of 38 maxillary sinuses.

SETTING: Tertiary care medical center.

PATIENTS: Nineteen adult patients with tumors of the head (but outside the sinonasal region).

INTERVENTIONS: Radiographic analysis.

MAIN OUTCOME MEASURES: The total volume of the maxillary sinus, volume above and below the superior attachment of the inferior turbinate, and volume anterior to the nasolacrimal duct were measured.

RESULTS: The mean (SD) total volume of the maxillary sinus was 20.1 (4.2) cm(3), whereas its volume inferior to the superior attachment of the inferior turbinate was 12.9 (3.7) cm(3) and anterior to the nasolacrimal duct was 1.1 (0.6) cm(3). The mean (SD) volume of the maxillary sinus inferior to the superior attachment of the inferior turbinate was 64% (12%), whereas the nasolacrimal duct obscured the transnasal anterior exposure of the maxillary sinus.

CONCLUSION: Without excision of the lateral nasal wall inferiorly to the nasal floor and anteriorly, including the nasolacrimal duct, over half of the maxillary sinus would be inaccessible for procedures directed at neoplasms within the maxillary sinus.