by ROBERT G. OJEMANN, M.D.

© Congress of Neurological Surgeons Honored Guest Presentation
Originally Published Clinical Neurosurgery, Volume 40, Chapter 17, Pages 321-383, 1992
Used with permission of the Congress of Neurological Surgeons.

HTML Editor: Stephen B. Tatter, M.D., Ph.D.

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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)
  • OLFACTORY GROOVE MENINGIOMAS (This File)
    • Management (This File)
    • Results (This File)
• References (File 22)

• FIG. 17.1. Olfactory groove meningioma. This 59-year-old man presented with a history of a subtle change in personality, less spontaneous activity, and mild difficulty with memory. Full recovery followed removal of the tumor. (A) MRI sagittal Tl image after gadolinium, showing the size of the tumor and the relationship to the optic nerve and ethmoid sinus. In this patient there is an unusual superior projection of the ethmoid sinus but no tumor has invaded the sinus. (B) MRI axial T2 image, showing the edema in the adjacent brain areas and the anterior cerebral artery slightly separated from the posterior capsule of the tumor. Angiography was not needed.

OLFACTORY GROOVE MENINGIOMAS

(Meningioma Management, File 2)

Management

MRI clearly defines the extent of the tumor, the edema in the surrounding brain, the relationship of the optic nerves and anterior cerebral arteries, and any extension into the ethmoid sinus (Fig. 17.1) (49). Angiography is rarely needed. In my experience, there has been no indication for preoperative embolization.

The indications for surgical treatment have been the presence of neurological symptoms, which may include a change in mental function, headache, disturbance in vision, or a seizure disorder, an asymptomatic patient with edema in the adjacent brain areas, or MRI findings that the meningioma is near the optic nerves (49). Radiation therapy is not recommended as a primary treatment and would be used only to treat recurrence following radical subtotal removal.

Rarely does the patient report loss of sense of smell as a symptom, although it is usually documented on examination. However, if olfaction is still present the patient should be warned about the loss of this function, since acute loss may be quite bothersome.

For patients with large tumors, I prefer a bifrontal craniotomy

• FIG. 17.2. Olfactory groove meningioma. (A) Incision and bone flap used for bifrontal cra.rdotomy. (B) The mucosa of the frontal sinus has been removed, and the sinus is packed with bacitracin-soaked getfoam and covered with a flap of peiicranial tissue sewn to the dura. (C) The anterior sagittal sinus is ligated. (D) The blood supply coming in through the midline base of the skull is being occluded and an internal decompression of the tumor done. (E) The capsule of the tumor is being reflected into the area of internal tumor decompression and the attachments to the surrounding brain divided. Minimal retraction is placed on the surrounding brain. The major trunk of the anterior cerebral artery is dissected off the tumor (arrow) but a branch going into the capsule is coagulated and divided. (F) The posterior inferior capsule is dissected off the arachnoid over the region of the optic nerve and internal carotid artery (arrows). (G) The dural attachment has been excised. The bone usually does not need to be removed. The area is covered with a graft of perieranial tissue and gelfoam.

(Fig. 17.2A-C) (47-49). This approach is associated with the smallest amount of retraction on the frontal lobes, gives direct access to all sides of the tumor, and allows one to decompress the tumor while working along the base of the skull to interrupt the blood supply. Guthrie et al. (26) and Long (38) also prefer the bifrontal exposure. For smaller tumors, a right subfrontal approach coming laterally over the orbital roof may be used (49). Hassler and Zentner (29) use a pterional approach. Logue (37) and Symon (74) use either exposure and may resect part of the frontal lobe, as do Solero et al. (69).

The key considerations in the operation include:

Dividing the attachments along the skull base to interrupt the blood supply (Fig. 17.2D).

Doing an extensive internal decompression of the tumor (Fig. 17.2D).

Retracting the tumor capsule into the area of decompression to keep traction on the frontal lobes to a minimum (Fig. 17.2E).

Carefully separating the tumor from attachments to the optic nerves and anterior cerebral arteries. The major branches of the anterior cerebral arteries are usually separated from the tumor by a rim of cerebral tissue or arachnoid but in large ineningiomas these arteries can be involved with the tumor capsule. Frontopolar and small branches of the anterior cerebral arteries may be adherent to the posterior or superior tumor capsule and can be taken with the tumor (Fig. 17.2F).

Excising the dural attachment and when present the hyperostotic bone, with care taken to avoid entering the ethmoid sinus unless it is known that tumor extends into that area (Fig. 17.2G). Symon (74) reported that the recurrence rate of these tumors is so low that there is no need to extensively treat the bone and I agree.

Covering the region of the dural attachment with a graft of pericranial tissue and gelfoam.

Results

There were 19 patients with olfactory groove meningiorna (Table 17.1). This group included 14 women and five men ranging in age from 23 to 73 years, with three over 70 years of age. Complete removal was done in 18 and one had a radical subtotal removal with a small fragment left on the internal carotid artery. In IS patients there was a good result. There was one postoperative death due to pulmonary embolus. In other reported series the operative mortality has also been low (29, 74).

The incidence of complications was low and did not interfere with eventual recovery. In this series one patient had a cerebrospinal fluid leak through the ethmoid sinus that required transethmoidal repair, one patient developed a wound infection that cleared, and one 71-year-old woman required treatment of a subdural hygroma with a subdural-peritoneal shunt. Disturbance in mental function and personality changes present preoperatively or transiently

TABLE 17.1 Olfactory Groove Meningiomas
aRemoval		bOutcome		Complications		Recurrence
T	18	Good	18	Cerebrospinal fluid leak	1	None
RST	1	Fair	0	Subdural Hygroma	1
ST	0	Poor	0	Pulmonary Embolus	1
		Death	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.

in the postoperative period usually recover completely. Preoperative visual symptoms usually recover and headache is relieved.

The recurrence rate has been very low. In this series there has been no evidence of recurrence and this has been confirmed by scans in 13 of the 19 patients over 1-12 years (mean, 4.4 years). Chan and Thompson (11) reported no recurrence during an average 9-year follow-up.

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