Contents

• Introduction to the therapy of Meningiomas (File 1)
• General Considerations in Management of Meningiomas (File 1)
  • Surgery of Meningiomas (File 1)
  • Radiation Therapy of Meningiomas (File 1)
  • Observation of Meningiomas (File 1)
• Summary of Dr. Ojemann's Meningioma Series (File 1)
  • MEDIAL SPHENOID WING (CLINOIDAL) MENINGIOMAS (This File)
    • Management (This File)
    • Results (This File)
• References (File 22)

FIG. 17.5. Medial sphenoid wing meningioma. This 59-year-old man presented with loss of vision in his right eye, increasing difficwty with memory, and a change in personality. Extensive subtotal removal was followed by a recovery of his mental function but no improvement in vision. (A and B) MRI axial (A) and coronal (B) TI images after gadolinium, showing the right internal carotid, middle cerebral, and anterior cerebral arteries surrounded by tumor. Edema in the adjacent brain areas, hydrocephalus, and severe compression of neural structures are noted. (C) Angiograin (lateral view) shows the elevation and encasement of the internal carotid artery.

MEDIAL SPHENOID WING (CLINOIDAL) MENINGIOMAS

(Meningioma Management, File 4)

Management

These meningiomas involve the region of the anterior clinoid, adjacent medial sphenoid wing, superior orbital fissure, and cavemous sinus. They may grow into the orbit. The tumor often encases the intemal carotid and proximal middle and anterior cerebral arteries as well as the optic nerve and may compress or provoke edema in the temporal or frontal lobes.

MRI outlines the extent of the tumor and shows the relationship to the arterial structures (Fig. 17.5, A and B). It is often hard to define the optic nerves and chiasm. Angiography is usually needed to determine the extent of encasement of the internal carotid artery and its branches (Fig. 17.5C). On rare occasions, especially with recurrence of an aggressive tumor, internal carotid occlusion is considered prior to surgery. Embolization of external carotid artery branches may occasionally be indicated.

The treatment decisions are often difficult. Prior to the development of CT and MRI and microsurgical techniques it was difficult to remove these tumors completely and there was significant morbidity. With the development of microsurgical techniques, some of these tumors now can be extensively removed. It remains to be established in the long term which patients benefit more from this extensive surgery with the increased risk of morbidity, from a partial removal of tumor followed by radiation therapy, or from radiation therapy alone.

Some general guidelines for the treatment of these tumors can be outlined. For patients with mild or nonprogressive symptoms it may be appropriate to follow the patient with periodic scans and examination to determine whether the lesion is growing and to see whether the symptoms are significantly interfering with the patient's life. The indications for surgery in younger patients are worsening symptoms and/or growth seen on follow-up scans and in older patients are large tumors with worsening symptoms. Radiation therapy is used in older patients with small and medium-size tumors with worsening symptoms and for regrowth after subtotal or radical subtotal removal.

The operative approach is similar to that used for tuberculum sella meningioma but with a more temporal exposure. It may be necessary to open the medial aspect of the Sylvian fissure to define the middle cerebral artery.

I prefer a frontal temporal craniotomy, as have others (9, 26, 47, 48). Al-Mefty and Smith (5) describe a cranio-orbital approach with section of the zygomatic arch and inclusion of the supraorbital ridge in the bone flap.

The key considerations in the operation include:

1. Intemal decompression of the tumor, staying away from the region of the internal carotid and middle cerebral arteries. Some soft tumors can be more easily removed than very fin-n hard tumors.
2. Identification of the distal branches of the middle cerebral artery and following them to the tumor capsule to determine whether it is feasible to dissect them. In some situations arachnoid planes help in separating the tumor from around the encased arteries.
3. Identification of the optic chiasm and following the optic nerve into the tumor.

Al-Mefty (1) has described a group of tumors that originate from the superior and/or lateral aspect of the anterior clinoid process. As the tumor grows the arachnoid membrane remains intact, making microsurgical dissection from the internal carotid artery and optic nerve possible. Brotchi and Bonnal (9) also emphasize the importance of the arachnoid membrane in aiding the dissection when there is arterial encasement.

Results

In this surgical series there were 17 patients (Table 17.3). There were 13 women and four men ranging in age from 28 to 79 years, with two over 70 years of age. In no patient could I be absolutely sure of a total removal because of involvement of important arteries and/or cranial nerves or the

TABLE 17.3 Medial Sphenoid Wing Meningiomas
aRemoval		bOutcome		Complications		Recurrence
T	0	Good	16	Neurological deficit	1	3 Given radiation therapy
RST	3	Fair	0
ST	14	Poor	1
aT, total removal RST, radical subtotal removal ST, subtotal removal bGood, free of major neurological deficit and able to return to previous activity level Fair, independent but not able to return to full activity because of new neurological deficit or significant preoperative deficit that did not fully recover Poor, dependent.

extension of the tumor into the cavernous sinus or orbit. In 16 patients there was a good result. One patient had a postoperative intracerebral hemorrhage 2 weeks after surgery and has a permanent dysphasia and hemiparesis.

In 11 patients no radiation therapy has been given and there has been no change in their tumor over a period of 1-11 years (mean, 5 year) after operation. Six patients were given radiation therapy, three immediately after operation and three when there was evidence of recurrence. Two of the patients with recurrence had reoperation and then radiation therapy to the small residual tumor, and one with diffuse involvement in the orbit and cavernous sinus was given radiation without further surgery. Following radiation therapy five patients are stable and one has shown slight growth over a relatively short follow-up.

Brotchi and Bonnal (9) reported total removal in nine of 28 patients, and 21 had no or minimal sequelae. Excellent results have been reported by Al-Mefty (1), with total removal in 20 of 27 patients.

To the MGH/MEEI/Harvard Cranial Base Center or the MGH Proton Beam Radiosurgery Homepage.

Members | Referrals | Newsletter | Guestbook Links | Selected Publications | CBC HomePage