Ludwig G. Kempe

Sphenoid Ridge Meningioma

Nearly all extracerebral, intracranial meningiomas have a common relationship in regard to their blood supply, vascularity, and relationship to neighboring structures. To prevent repetition, only the pertinent operative maneuvers of the specific lesion at hand are shown ; but, if they are taken together with the other chapters dealing with meningiomas, we believe that an exhaustive description is given. Beginning with the tuberculum sellae meningioma, the reader and student should review all chapters presenting the operative handling of meningiomas.

Olfactory Groove Meningioma

Anosmia is the initial clinical sign of an olfactory groove meningioma. Later on, as the tumor reaches a larger size, visual field defects and personality changes are observed. In the diagnostic studies angiography will reveal elevation and stretching of the anterior cerebral and frontal polar arteries (Figs. 140 and 141). The vascular supply comes from the anterior ramus of the middle meningeal artery and the anterior ethmoidal artery which is a branch from the usually widened ophthalmic artery. The venous phase indicates the size of the meningioma by its diffuse staining. A combined angiographic-pneumoence-phalographic study will give additional information as to the side on which the larger mass of the tumor is situated. The attachment to the floor of the anterior fossa is over the posterior cribiform plate and planum sphenoidale. Fig. 142 shows a predominantly left-sided olfactory groove meningioma extending back, depressing the optic nerve and chiasm. Its relationship to the optic nerve and chiasm is different from that of a tuberculum sellae meningioma (see p. 94, Chapter VI). The operative removal of the olfactory groove meningioma in Fig. 142 will be discussed.

Tumors of the Third Ventricle

The third ventricle may be invaded from below by a pituitary tumor or a craniopharyngioma; if such is the case the operative technique is as described in Chapters IV and V. A large aneurysm situated at the bifurcation of the basilar artery may bulge into the third ventricle, cause obstructive hydrocephalus and be mistaken for a third ventricular tumor. If properly diagnosed the aneurysm will be handled subtemporally and is discussed in a later chapter. For true third ventricular tumors (colloid cyst, pinealoma, etc.) and for the occasionally superiorly placed craniopharyngioma, the operative approach is from above. There are two such approaches to the third ventricle. One is from above anteriorly through the lateral ventricle and the foramen of Monro (Fig. 206) and the other approach is from above and posteriorly through the splenium of the corpus callosum (Fig. 216).

Aneurysm, Anterior Part of Circle of Willis

This chapter discusses aneurysms originating from the intracranial portion of the internal carotid artery where it emerges from the cavernous sinus below the anterior clinoid process to its bifurcation into the anterior and middle cerebral arteries. Cavernous sinus fistulae or aneurysms of the intracavernous sinus portion of the internal carotid artery are not described. These latter lesions are nearly always treated by trapping or embolization procedures and present no technical operative difficulties. The ligation of the ophthalmic artery which is indicated in the treatment of cavernous sinus fistulae will be presented in a separate section.

Craniotomy, Frontotemporal, Opening and Closure

One of the most frequently used craniotomy sites over the fronto-temporal area is selected to show the operative steps. The head is shaved just prior to bringing the patient to the Anesthesia Induction Room. While under anesthesia the patient is positioned for surgery, in our case of a left frontotemporal craniotomy the head is turned as seen in Figs. 1 and 2. Care is taken that neck muscles are not taut to prevent any compression of the venous circulation. This is accomplished by keeping a firm pillow under one shoulder, depending on the way the head is turned (Fig. 1a and b). Another important rule in positioning the patient is to keep the head always above the level of the heart. It may be necessary or helpful to lower or turn the head during certain operative procedures. This possibility should be kept in mind ; however, even after repositioning the patient’s head should remain above the heart level (Fig. 2). The head may be placed on a doughnut-shaped headrest or a three-pronged head holder, either of which permits repositioning of the head during surgery. The eyes are now covered with a rubber sheet after inserting into the conjunctival sacs a mild aseptic ophthalmic ointment. The scalp is prepared with soap and water and an iodine-containing solution.

Tuberculum Sellae Meningioma

The first clinical sign and symptom of the meningioma located over the tuberculum sellae is a defect in the field of vision. Invasion of the cavernous sinus will lead to extraocular muscle paralysis and fifth nerve involvement. Larger and more extensive lesions impair pituitary and hypothalamic function.

Aneurysm of the Basilar Artery

Many of the same principles which apply to the operative treatment of aneurysms of the anterior part of the circle of Willis are observed in the surgical therapy of aneurysms of the basilar artery. We have found no advantage in hypothermia or hypotensive techniques prior to ligating the aneurysm, for the possible advantages appear to be outweighed by the disadvantages. If the aneurysm should bleed at the time of exposure, hypothermia affords little extra protection and prolongs significantly anesthesia with an associated increase in postoperative problems. Also, pre-existing hypotension accentuates hypoxia and ischemic damage to the brain stem with fresh bleeding. However, controlled hyperventilation anesthesia is used as in all neurosurgical procedures as long as the patient is not in the sitting position. In the majority of our cases aneurysms of the basilar artery are reached via the subtemporal approach and this method is described.

Falx and Parasagittal Meningiomas

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.

Retrobulbar Intraorbital Tumors (Optic Nerve Glioma)

In mass lesions situated behind the optic globe the intracranial approach remains the method of choice. In tumors of the optic nerve, the transcranial approach is the only way to manage the possible intracranial extension of the tumor. Lesions situated anteriorly, laterally and inferiorly to the globe are in the domain of the ophthalmologists. The case presented is a dumbbell-shaped, right-sided optic nerve glioma. On occasion a patient with this type of tumor will still have fairly adequate vision. Since the response to radiation and repeated radiotherapy can be quite dramatic and can, on occasion, maintain vision over years, the pros and cons of total extirpation of this lesion have to be discussed with the patient or his guardian. If the tumor involves the optic chiasm and the patient’s vision is satisfactory, biopsy and radiation therapy are to be recommended.

Lateral Tentorial Meningiomas

Twelve meningiomas situated in the region of the asterion have been operated upon over the past 18 years at Walter Reed General Hospital. These tumors invaded the transverse sinus at its junction into the sigmoid sinus. The superior petrosal sinus which enters the transverse sinus in this area had to be ligated separately only in two instances. However, most of these tumors did extend from the middle into the posterior fossa and required a combined temporal-suboccipital craniectomy. In Fig. 299 an anatomical drawing outlines the relationships of the tumor to the skull, dura, dural sinus, and tentorium. The temporal lobe, the cerebellum, the tumor and its invasion into the transverse sigmoid sinus are seen in a coronal section (Fig. 300). The main blood supply to the asterion meningioma comes from the middle meningeal artery and the occipital artery. The richness of this blood supply demonstrated angiographically will help decide if ligation of the external carotid artery should be done prior to removal of the tumor.