Sphenoidal Ridge Meningioma

Abstract

Sphenoidal ridge meningiomas originate from this sharp limit separating the subfrontal region from the temporal fossa. As Cushing and Eisenhardt⁵ put it in their Monography published in 1938: “Sharply demarcating frontal from middle basilar fossa, a bony ridge curves outward on a horizontal plane from the anterior clinoidal process toward the lateral aspect of the cranial chamber where it flares out to become lost in the pterional region of the cranial vault. This landmark, commonly referred to by neurosurgeons as the “sphenoidal ridge”, may conveniently be divided into three more or less equal portions: 1. deep, inner or clinoidal: 2. middle or alar: and 3. outer or pterional. The inner two thirds roughly correspond to the posterior margin of the lesser sphenoidal wing (ala parva): the outer third to the flaring margin of the greater wing (ala magna)”. This description was based on anatomical, surgical and clinical considerations. With the development of new diagnostic procedures (CT–Scan and MRI) technical problems become preponderant, so that it seems more appropriate to divide these tumors into two groups: medial arising from the inner third, lateral from the external two thirds of the ridge.