Читать книгу Anterior Skull Base Tumors - Группа авторов - Страница 82

Although extracranial meningiomas may arise from the sinonasal tract and involve the ASB floor from “below,” direct extension of an intracranial meningioma is much more common. Because of its site of origin (from the olfactory groove, anteriorly, to the clinoids, posteriorly) and its pattern of growth, meningioma is both the prototype of a tumor arising in close contact with the ASB floor and the most frequent one (Fig. 16). According to the literature, TES demonstrates an inferior rate of complete resection of anterior cranial fossa meningiomas compared with open transcranial approaches [46]. Among the numerous elements that may explain such a limitation, three factors, belonging to the domain of pretreatment imaging, have been recently emphasized and also reported in a scoring system [47]. Basically, these factors are the degree of hyperostosis induced by the lesion at the level of the ASB floor, the resectability of the tumor once it extends into the cavernous sinus and involves the ICA, and the extent of the dural tail in the transverse plane compared to the length of the interfovea ethmoidalis distance.

Fig. 15. ONB. Coronal (a) and sagittal (b) TSE T1 after contrast administration. a Enhancing nasoethmoidal mass invading both sides of the ACF showing a “waist” at the passage between the ethmoid and the ACF. The tumor (T) shows intracranial intradural invasion, peripheral “cysts” are present (thin white arrows). The tumor extends into a blocked frontal sinus (white arrow in b).

Fig. 16. Meningioma of the olfactory groove/planum sphenoidale. CT, bone window. Marked reactive hyperostosis of the planum sphenoidale (black arrowheads) is induced by the meningioma (white arrows), which also causes enlargement and an “upward pulling” of the sinus (pneumosinus dilatans; curved arrow).