Suprasellar Meningioma Classification: Endoscopic Transnasal Perspective.

Objectives Midline suprasellar meningiomas include planum sphenoidale, tuberculum sellae, and diaphragma sellae meningiomas. Multiple classifications have been previously documented; however, they come with controversies and limitations, including those with surgical implications. The aim of this study was to classify suprasellar meningiomas based on their behavior toward the underlying bone and neurovascular structures. Methods Patients with newly diagnosed suprasellar meningiomas that underwent extended endoscopic transnasal approach between 2015 and 2021 were included in this study. The following parameters were evaluated: chiasmatic sulcus length, location of the optic chiasm and nerves, optic canal involvement, and vascular displacement. Results We identified 40 cases of midline suprasellar meningiomas, 1 diaphragma sellae meningioma (type A), 10 tuberculum sellae meningiomas (type B), 9 chiasmatic sulcus meningiomas (type C), and 10 planum sphenoidale meningiomas (type D). Asymmetrical visual complaints were most common in chiasmatic sulcus meningiomas, followed by tuberculum sellae meningiomas (66 and 50%, respectively). Chiasmatic sulcus meningiomas showed increased separation between the optic chiasm and the A1/A2 complex (8.9 mm) compared with tuberculum sellae (2.7 mm) and planum sphenoidale (1.9 mm) meningiomas. Compared with other types, increased chiasmatic sulcus length was observed in chiasmatic sulcus meningiomas. Conclusion Preoperative evaluation of bone involvement and tumor relation to neurovascular structures can be used to classify suprasellar meningiomas. Chiasmatic sulcus meningioma is a distinct subtype of suprasellar meningiomas. Its unique behavior toward nearby neurovascular structures could be of surgical value during tumor resection.

Classification of Endoscopic Transnasal Lateral Skull Base Approaches: Anatomical Study.

OBJECTIVE: Endoscopic transnasal approaches (ETAs) to the ventrolateral skull base are commonly classified according to coronal planes or anatomical structures. Our goal is to simplify the description of the ETA to lateral skull base regions in a sequential dissection with correlation to computed tomography, helping in preoperative planning and efficient surgical exposure, and exposing the surgical anatomy limitations. METHODS: Five freshly injected cadaver heads were dissected using an extended ETA to the lateral skull base. Each specimen underwent a high-resolution computed tomography scan. A classification of the lateral skull base based on well-defined zones was proposed. RESULTS: We divided the lateral target into four different zones, in a craniocaudal orientation: zone 1 is the space lying between the orbital floor superior and the level of the sellar floor inferior, zone 2 is on the coronal plane, located between the level of the sellar floor and the vidian canal, zone 3 is the area lateral to the anterior limb of the petro-occipital fissure, located between the vidian canal and the carotid canal, and zone 4 is the space located between the carotid canal and the extracranial opening of the hypoglossal canal, lateral to the anterior part of the posterior limb of petro-occipital fissure. CONCLUSIONS: Multiple previous works have described and classified the coronal plane and its lateral extensions. Our classification system for the proposed lateral zones enables preoperative planning to select a suitable approach. The craniocaudal orientation facilitates the understanding of surgical corridors and tailored exposure.