Modular Endoscopic Medial Maxillectomies: Quantitative Analysis of Surgical Exposure in a Preclinical Setting

BACKGROUND: Endoscopic medial maxillectomies (EMM) have been named with different nomenclatures. Aim of the present study was to objectively measure the surgical exposure in a preclinical anatomical setting to validate a classification for modular EMMs. MATERIALS AND METHODS: Six cadaver heads underwent computed tomography and images were uploaded on a dedicated software. A neuronavigation system was used to measure areas and volumes of surgical corridors during dissection. A difference of more than 10% of area exposed and 3 cm3 of volume were considered to define incremental types of EMM. Specific anatomical targets were assessed on the axial and sagittal plane. The influence of anatomical variants on surgical exposure was evaluated. RESULTS: Four types of EMMs (A-D), with a trans-septal (TS) variant each, were identified. On the axial plane, vidian canal and foramen rotondum were reached with type A, foramen ovale and spinosum with type B, and coronoid process with TS-type C or type D. On the sagittal plane, type A exposed the vidian canal, whereas foramen ovale and the styloid process were reached by type B. The pterygomaxillary fissure was exposed with TS-type C, while the inferior border of the lateral pterygoid plate required a type D. Nasal floor limits the downward angle in TS approaches. Width of the piriform aperture independently influenced the surgical volume of types B and C. CONCLUSIONS: This modular classification of EMMs, based on a quantitative analysis in a preclinical setting, should allow for better personalized preoperative surgical planning and provides standardization of nomenclature.