File 19: FORAMEN MAGNUM MENINGIOMA
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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.
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
FORAMEN MAGNUM MENINGIOMAS
| 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)
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
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.
- 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.
- The llth nerve rootlets are separated.
In some cases the posterior upper cervical roots need to be divided.
- 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
- 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
aT, total removal
RST, radical subtotal removal
ST, subtotal removal
bGood, free of major
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
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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