Falx and Parasagittal Meningiomas

Abstract

In this chapter the operative techniques of three meningiomas of the falx are given: (1) deep-seated unilateral falx meningioma, (2) parasagittal meningioma with invasion into the superior sagittal sinus, and (3) bilateral parasagittal meningioma. The value of the preoperative angiography in meningiomas has been discussed in Chapter VI, VIII and IX. In meningiomas of the falx not only are the same principles true but also required is a bilateral angiogram to obtain information in regard to bilateral extension of the tumor and invasion or obliteration of the venous sinus. If obstruction at the sagittal sinus is found, the main drainage of the hemispheres may go into the inferior sagittal sinus just below the tumor. Such a pathway has to be seen in the roentgenographic study and preserved during surgery. Visualization of arterial feeders to the meningiomas from branches of the external carotid artery (middle meningeal artery, superficial temporal artery, and the external occipital artery) requires the angiogram to include injection of the external carotid artery. But not all convexity meningiomas receive blood supply from the external carotid artery. In faix meningiomas especially, the main feeders may come from the pericallosal and middle cerebral arteries. Thus, the decision as to ligation of the external carotid artery to reduce bleeding is made, based on a complete angiographic study.