Surgical treatment of anterior basal meningiomas.

Meningiomas of the anterior skull base account for 40% of all intracranial meningiomas. Of these, almost half are sphenoid wing meningiomas; the other half are tuberculum sella tumors or olfactory groove tumors. Anterior clinoidal (medial sphenoid wing) meningiomas are a subcategory of the sphenoid wing meningiomas; they fall into one of three categories according to the presence of an interfacing arachnoidal membrane between the tumor and the cerebral vessels. Meningiomas of the tuberculum sella arise from the tuberculum sella, chiasmatic sulcus, limbus sphenoidale, and the diaphragma sella; they may extend into both optic canals. Olfactory groove meningiomas arise more anteriorly than do the tuberculum sella meningiomas and may be symmetrical around the midline or extend to one side or the other; at least 15% grow into the ethmoid sinuses. This paper addresses the clinical presentation, preoperative evaluation, and surgical procedures used for treating tumors of the tuberculum sella, the olfactory groove, and the anterior clinoid.