FIG. 17.12. Parasagittal meningioma. This 37-year-old woman presented with headache and left visual field symptoms. At operation the edge of the sinus was opened to remove the tumor. She made a non-nal recovery. The MRI axial T2 image shows the involvement of only the lateral edge of the sinus. Note the thin layer of cortex between the falx and the tumor.

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.

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)
  • PARASAGITTAL MENINGIOMAS (This File)
    • Management (This File)
    • Results (This File)
• References (File 22)

FIG. 17.13. Parasagittal meningioma. This 71-year-old man presented with increasing weakness in the left lower extrendty and a sensory seizure. At operation a thin plaque of tumor was left on the wall of the sagittal sinus. Postoperatively, there was increased weakness in the left lower extremity, which recovered over several months. The last scan 2 years after operation shows no regrowth. (A and B) MRI coronal (A) and sagittal (B) TI images after gadolinium. The right parasagittal meningioma extensively involves the wall of the sagittal sinus and adjacent convexity dura and falx. (C and D) Angiogram shows the position of the cortical veins (C), and the oblique view (D) confirms the open sagittal sinus.

PARASAGITTAL MENINGIOMAS

(Meningioma Management, File 11)

Management

These meningiomas involve the sagittal sinus and the adjacent convexity dura and falx. There are two general categories of these tumors. The first involves only the lateral edge of the sagittal sinus (Fig. 17.12) and adjacent convexity dura and the second extensively involves the sinus, adjacent falx, and convexity dura (Fig. 17.13, A and B). The overlying bone may be involved in tumor and in some cases there may be hyperostosis. In considering both the symptoms and the surgical aspects of these tumors, it is useful to divide them into those that occur along the anterior, middle, and posterior third of the sagittal sinus (14, 20, 26, 42, 47, 77). In general terms, the anterior third of the sinus extends from the cristi galli to the coronal suture, the middle third from the coronal to the lambdoid suture, and the posterior third from the lambdoid suture to the torcula.

MRI outlines the tumor and may indicate the status of the sagittal sinus (FIG. 17.13, A and B). Angiography is usually needed to assess the status of the sinus and the relationship of the cortical veins (Fig. 17.13, C and D).In some patients MR angiography may give the information needed. Embolization has not been needed.

The indications for surgery are worsening neurological symptoms, seizure in younger patients, and regrowth after radical subtotal removal. Radiation therapy has not been used. Observation is recommended in many older patients with a seizure or minimal symptoms.

FIG. 17.14. Parasagittal meningioma. Positions and incisions for operation. The approximate center of the tumor is the highest point. (A) Anterior third of sagittal sinus. (B) Middle third of sagittal sinus. (C) Posterior third of sagittal sinus.

Key considerations in the operation include the following:

1. The patient is positioned so the scalp over the center of the tumor is the highest point. For meningiomas anterior to the coronal suture the patient is placed supine with the head elevated and a coronal incision is made (Fig. 17.14A). For tumors in the middle third of the sagittal sinus the patient is placed in the semi-lateral semi-sitting position with the head well elevated so the scalp over the area of the tumor is at the highest point (Fig. 17.14B). For tumors involving the posterior third, the patient is placed in the lateral position and the head is elevated and turned to the opposite side so that the center of the tumor is uppermost (FIG. 17.14C) (53).
2. The incision for anterior tumors is usually a coronal incision (Fig. 17.14A), for tumors at the level of the coronal suture a horseshoe incision that turns forward, for tumors of the middle third a horseshoe incision that extends across the rnidline (FIG. 17.14B), and for posterior-third lesions a horseshoe incision that turns inferiorly (FIG. 17.14C). The skin flap must be large enough to give adequate exposure around the tumor.
3. The bone flap is carried about 2 cm across the midline to the side opposite the tumor. If vascularity is a problem, the bone flap may be turned in two sections, one over the convexity area and the second over the sagittal sinus.
4. The dura over the convexity is cut at least I cm away from the tumor if at all possible (Fig. 17.15A). When the sinus is to be divided it should be opened before the ligature is tied. On more than one occasion I have removed a tongue of tumor growing in the lumen of the sinus beyond the margin of the tumor. When the tumor involves only the edge of the sinus the dura is initially cut a few millimeters parallel to the sinus, leaving a small plaque of tumor (FIG. 17.15B).
5. The tumor is internally decompressed, if needed, to avoid traction on the surrounding brain (Fig. 17.15B). The capsule is carefully reflected into the area of decompression, dividing arachnoid and vascular attachments and protecting the brain with cottonoids (Fig. 17.15C).
6. In the anterior-third lesions a total removal can usually be done, including the sagittal sinus and falx, even if the sinus is open. In the middle third total removal can be done if the sinus is occluded. If only the edge of the sinus is involved it may be opened with removal of the residual plaque of tumor and edge of the sinus wall, which is then progressively closed with a continuous suture (Fig. 17.15D). This is also true for those tumors in the posterior third. When the sinus is extensively involved with tumor in the middle or posterior third and is still open, tumor must be left in the wall (FIG. 17.13).

FIG. 17.15. Parasagittal meningioma. Steps in resection of tumor involving the lateral wall of the sagittal sinus are shown. (A) The convexity dura is cut at least I cm from the tumor and the arachnoid and cortical attachments along the tumor capsule are divided. (B) The dura is cut parallel to the sinus, initially leaving a small plaque of tumor, and an internal decompression of the tumor is done with the eavitron or cautery loops. (C) The capsule is reflected into the area of decompression as it is separated from the cortex. The cortex is protected with cottonoids. (D) The edge of the sinus is opened a few millimeters at a time to remove the tumor attachment. The opening is closed with a continuous suture.

Results

In this series there were 43 patients, 32 women and 11 men, ranging in age from 25 to 81 years, with 11 over 70 years of age. In 27 patients only the edge of the sinus was involved (Table 17.9). In all of these patients a gross total resection was done by opening the sinus and resecting it, but there was often not more than 1 or 2 mm of margin between the tumor and the edge of the resection. In 24 of the 27 patients there was a good result; three had a fair result because of significant preoperative deficits that did not fully recover. Four patients had temporary weakness in one or both contralateral extremities. No patient had permanent worsening due to the operation. Two patients had pulmonary emboli.

Two patients have had recurrence of the tumor three and 11 years after the first operation. In both, another gross total removal was done with a full recovery. In 17 other patients follow-up scans have not shown any recurrence over a period of 1-10 years (mean, 4.6 years).

TABLE 17.9 Parasagittal (Edge of Sinus) Meningiomas
aRemoval		bOutcome		Complications		Recurrence
T	27	Good	24	Temporary deficit	4	2
RST	0	Fair	3 (3)
ST	0	Poor	0
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 16 patients there was extensive involvement of the sagittal sinus (Table 17.10). All six patients with tumors in the anterior third had complete removal and made a good recovery and there has been no recurrence. Ten patients had tumors in the middle third. They often had more deficits preoperatively and frequently had temporary increases in hemiparesis or sensory loss postoperatively. In six patients there was significant postoperative worsening which improved in weeks or months, but in two of these patients a moderate paralysis persisted. Five patients had a good result and five a fair result. Three of the patients with fair results were the same or better than before operation but still had residual preoperative disability and two had new postoperative disabilities. In six

patients it was possible to do a total removal because the sinus was occluded by the tumor. In the other four, tumor was left in the wall of the open sinus. Follow-up scans from I to 4 years have shown no change in three. In the other patient gradual regrowth of tumor was noted on scan but it was not symptomatic until 7 years after operation, when seizures recurred. Angiography showed the sinus to be occluded and a total removal was done. There has been no recurrence.

Wilkins (77) has summarized the results from several series of patients. Giombini et al. (20) reported that of 27 anterior-third cases 17 (63%) had no disability and 10 (37%) had partial disability. Of 69 middle-third cases 36 (39%) had no disability, 53 (77%) partial disability, and four (6%) cormplete disability. In the posterior third, five (45%) had no disability and six (35%) had partial disability.

TABLE 17.10 Parasagittal (Sinus Involved) Meningiomas
aRemoval			bOutcome			Complications			Recurrence
	Anterior Third	Middle Third		Anterior Third	Middle Third		Anterior Third	Middle Third
T	6	6	Good	6	5	Temporary deficit	0	4	0 Anterior third
RST	0	4	Fair	0	5 (3)
ST	0	0	Poor	0	0	Permanent deficit	0	2	1 Middle third
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.

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