File 18: CEREBELLAR CONVEXITY 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
| FIG. 17.32. Cerebellar
convexity meningioma. This 65 year-old woman had increasing
difficulty in walking. Total removal was followed by full recovery.
The CT scan shows a large tumor arising from the junction of
the petrous and cerebellar convexity dura on the right side.
Cerebellar tissue has been compressed anteriorly and medially.
CEREBELLAR CONVEXITY MENINGIOMAS
(Meningioma Management, File 18)
These meningiomas can be divided into
two groups. One arises from the dura over the posterior convexity
of the cerebellum and the other arises in the angle between the petrous
and convexity dura and may include the wall of the sigmoid and lateral
transverse sinuses (FIG. 17.32). These meningiomas are usually separated
from the cranial nerves by cerebellar tissue but in very large tumors
there may be only a thin layer of arachnoid. MRI gives most of the
information the surgeon needs. Angiography may be indicated to determine
the status of the venous sinuses. Surgery is indicated when the patient
has neurological symptoms, usually headache or progressive cerebellar
signs. Radiation therapy has not been used.
For most patients I prefer to use
the same approach as described for cerebellopontine angle tumors.
In some patients the exposure extends above the sinus or into the
mastoid. Several different approaches and incisions have been reviewed
by Kobayashi and Nakamura (32). The key considerations in the operation
are the same as those outlined for meningiomas in general (see "General
Considerations in Management").
If the sigmoid or transverse sinus
is occluded this is resected. In most patients the sinuses are open.
In these patients a layer of dural attachment over the sinus can
often be removed.
In this series there were six patients,
five women and one man, ranging in age from 56 to 75 years, with one
over 70 years of age (Table 17.17). Three of these lesions arose from
the cerebellar convexity dura and three were over the sigmoid sinus.
A gross total removal was done in five and a radical subtotal
removal in one, with tumor left in the wall of the sinus. All made
a full recovery. There have been no recurrences. Only a few small
series of patients have been reported. Martinez et al. (40) summarized
the reports to 1982. Kobayashi and Nakamura (32) noted that, with
the advent of microsurgical techniques, the results have generally
been good to excellent.
|TABLE 17.17 Cerebellar
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
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