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Management of Meningiomas
File 19: FORAMEN MAGNUM MENINGIOMA

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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.


Disclaimer: The information and reference materials contained herein are intended solely to provide background information. They were written for an audience of physicians. They are in no way intended to constitute medical advise. For medical advise a physician must, of course, be consulted.

Contents


FORAMEN MAGNUM MENINGIOMAS

Meningioma MR scan
FIG. 17.33. Foramen magnum meningioma. This 49-year-old woman noted increasing difficulty using her right upper extremity and weakness of her right lower extremity. An angiogram showed mild compression of the vertebral artery. Total removal was followed by full recovery. (A and B) MRI axial images, showing the tumor arising from the right anterior lateral dura with displacement of the brainstem posteriorly and to the left. (C) MRI sagittal image, showing the posterior compression of the cervical medullary junction and the longitudinal extent of the tumor.

(Meningioma Management, File 19)

Management

These meningiomas usually arise from the anterior-lateral dura at the foramen magnum but can occur directly anteriorly, posteriorly, or posterior-laterally. MRI clearly defines the relationship of the tumor to the surrounding structures (Fig. 17.33). Angiography should be done to define the position of the vertebral artery and its branches and demonstrate the vascular supply. We have not seen a case when embolization was needed, but it has been reported.

Surgery is indicated when there are worsening neurological symptoms. Radiation therapy has not been used.

For most patients I prefer to use the prone position with a midline incision, suboccipital craniectomy, and upper cervical laminectomy. The details of the tumor removal have been outlined by Scott and Rhoton (62).

The key considerations in the operation include the following.

  1. The dura is opened in a Y-shaped fashion with the vertical limb toward the side of the tumor. If the venous sinus in the dura is significant, it is closed with a running suture; otherwise, bipolar coagulation is used.
  2. The llth nerve rootlets are separated. In some cases the posterior upper cervical roots need to be divided.
  3. An internal decompression of the tumor is done before separating the capsule from the spinal cord, medulla, and vertebral artery. Occasionally, a small area of tumor may be left adherent to the vertebral artery. The vertebral artery is identified where it enters the dura at the highest dentate ligament.
  4. In some patients the dural attachment can be removed; in others, where there is an anterior extension or involvement near the vertebral artery, the internal dural surface may be peeled away. The dura is closed with a graft of pericranial tissue taken from the occipital region.

Other approaches to these tumors have been summarized (18, 26, 62). George (18) uses a posterolateral approach. Crockard (13) uses the transoral approach for those meningiomas that are in the midline with no lateral extension.
TABLE 17.18 Foramen Magnum Meningiomas
aRemoval bOutcome Complications Recurrence
T 5 Good 5 None None
RST 0 Fair 0
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.

Results

In this series there were five patients, all women, ranging in age from 33 to 65 years (Table 17.18). All had total removal and all returned to normal activity. There have been no recurrences. Scott and Rhoton (62) have summarized the results of several series. Between 70 and 80% had a good result.

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