File 13: CONVEXITY MENINGIOMAS
To the MGH/Harvard
Meningioma Treatment Homepage
To the Introduction and Contents of Management
of Cranial and Spinal Meningiomas
Members | Referrals
| Newsletter | Guestbook
| Links |
Selected Publications | CBC
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. 17.20. Convexity
meningioma. Selective external carotid angiogram shows the
typical hypertrophied middle meningeal artery that supplies
these tumors. Angiography is no longer used because we know
that this blood supply can be occluded as the dura is opened
around the tumor. There is no need to do embolization.
(Meningioma Management, File 13)
| FIG. 17.21. Convexity
meningioma. Incision and bone flap for a meningioma centered
along the coronal suture.
Convexity meningioma describes those
tumors whose attachment does not occur on the dura of the skull
base or does not involve the dural venous sinus or falx. The tumor
may arise from any area of the dura over the convexity, but they
are more common along the coronal suture and near the parasagittal
region. Various classifications regarding location have been proposed
(19, 42). Patients usually present with seizures, headache, or a
focal neurological deficit, depending on the tumor location.
In most situations MRI gives all the
information one needs. I no longer do angiography for most patients
with convexity meningiomas since blood supply is known and the procedure
does not add any crucial information for planning the operation.
Embolization is not needed in these patients. The feeding meningeal
arteries can be occluded early in the course of the operation (Fig.
Surgery is indicated in patients with
worsening neurological symptoms and in most patients under 70 who
present with a seizure or with any neurological symptoms. If patients
are over 70 and present with a seizure or have mild symptoms, they
can be followed with scans and undergo surgery if there is evidence
of definite growth. However, if there is significant edema or a
history of worsening symptoms, age is not a contraindication to
surgery. A number of patients are now seen in whom the tumor is
found incidently and there is no edema. These patients can be followed
with periodic scans, including those with large tumors. Radiation
therapy is not recommended in this group.
The details of the operation have
been reported by several neurosurgeons (19, 26, 41, 47, 53). The
key considerations in the operation include the following.
| FIG. 17.22. Convexity
meningioma. This 58-year-old woman presented with a seizure.
Total removal was followed by a full recovery. (A and
B) MRI axial (A) and coronal (B) T2 images
show the relationship of the middle cerebral artery to the convexity
meningioma projecting into the sylvian fissure. The edema
in the adjacent brain areas is also seen. (C) During
tumor removal the surgeon must remember that the middle cerebral
artery branches may be adherent to the media] capsule.
- The head is positioned so that the
center of the tumor is uppermost, the same position as described
for parasagittal tumors or for tumors close to the midline.
- The incision and bone flap must
be large enough to allow for excision of a good margin of dura
around the tumor attachments (FIG. 17.21).
- The meningeal arteries are occluded
as they are exposed.
- These tumors can be removed intact
by placing gentle traction on the dural attachment and working
circumferentially around the tumor to divide the attachments to
the cortex. However, if the surface of the tumor cannot be easily
visualized without placing significant retraction on the cortex,
internal decompression of the tumor is done and the capsule is
reflected into the area of decompression.
- In a situation where the tumor arises
over the frontal temporal junction and grows into the sylvian
fissure, the medial capsule and the dural attachment may extend
down onto the lateral floor of the anterior fossa and anterior
wall of the middle fossa, and the medial capsule of the tumor
can be attached to branches of the middle cerebral artery (Fig.
In this series there were 66 patients,
44 women and 22 men, ranging in age from 31 to 82 years, with 18
over 70 years of age (Table 17.12). All were symptomatic except
for one with an enlarging tumor on follow-up scan. All but one patient
had total removal of their tumors. The one exception was an 80-year-old
man with a large tumor growing into the sylvia,n fissure at the
frontal-temporal junction. A small fragment of tumor was left adherent
to the middle cerebral artery.
Postoperative complications included three
with a temporary increase in hemiparesis and sensory loss, one with
difficulty controlling seizures, one wound infection, and one with
deep venous thrombosis. All patients had a good result. There has
been evidence of only one recurrence. This was in a patient with an
atypical meningioma with regrowth 5 years after resection. The recurrence
was removed and there has been no further recurrence over 9 years.
The low rate of recurrence has been documented in other publications
(I 1, 44).
|TABLE 17.12 Convexity
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
How long a patient should remain on
anticonvulsant medication after these operations has not been established.
If there is a history of preoperative seizure, long-term medication
may be required. If there has been no history of seizure, we usually
taper off the medication 2-3 months after operation.
To the MGH/MEEI/Harvard
Cranial Base Center or the MGH
Proton Beam Radiosurgery Homepage.