File 17: CEREBELLOPONTINE ANGLE MENINGIOMA
| FIG. 17.30. Cerebellopontine
angle meningioma. This 41-year-old woman noted increased
numbness in the left side of her face and decreased hearing
in her left ear. A radical subtotal removal was done, with tumor
left encasing the fourth nerve and going into the anterior wall
of the internal auditory canal. (A-D) MRI axial TI images
after gadolinium show the typical appearance of a meningioma,
with the flat surface against the petrous bone and the dural
"tails." This tumor is arising anterior to the left
internal auditory meatus. It may extend into the internal auditory
meatus, as seen here.
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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
CEREBELLOPONTINE ANGLE MENINGIOMAS
(Meningioma Management, File 17)
These meningiomas may arise from any
area of the dura on the postelior surface of the petrous bone. At
operation four general categories of tumor are found, depending
on where they arise and their relationship to the seventh and eighth
- Anterior to the internal auditory
meatus, displacing the seventh and eighth nerves posteriorly and
inferiorly (Fig. 17.30).
- Between the internal auditory meatus
and the jugular foramen, displacing the seventh and eighth nerves
- Superior to the internal auditory
meatus, displacing the seventh and eighth nerves anteriorly in
the large tumors (Fig. 17.31).
- Surrounding the internal auditory
meatus, with the seventh and eighth nerves engulfed in the tumor.
The MRI scan usually defines those tumors
that arise posterior to the internal auditory meatus but will not
distinguish the first three categories. The diagnosis of meningioma
is indicated by the flat surface of the tumor against the petrous
bone and the durat "tail" extending from the tumor.
| FIG. 17.31. Cerebellopontine
angle meningioma. This 40-year-old woman had progressively
decreased hearing in her left ear and discomfort around her
ear and the side of her head. Total removal of the tumor was
done using a combined posterior fossa and transmeatal approach.
There was normal recovery. (A-D) MRI axial TI images
after gadolinium show a large meningioma arising posterior to
the left internal auditory meatus.
In the past I often utilized angiography
when a cerebellopontine angle meningioma was suspected. However,
for most of these meningiomas it is now not necessary, because the
MRI usually gives all the information needed and in most patients
the blood supply comes primarily through the dural attachment. Embolization
has not been a consideration.
In patients with mild or minimal symptoms,
an initial period of clinical evaluation and repeat scans may be
indicated to determine whether there are progressive symptoms and
an enlarging tumor. This is especially true in the elderly.
The indications for operation are
a worsening neurological deficit due to brainstem compression or
cranial nerve compression. In a few patients headache or the continued
presence of a stable deficit such as diplopia or hearing loss may
be the indication. In this series two patients were asymptomatic.
One had documented enlargement on follow-up scans and the other
was concerned about the presence of the tumor. Radiation therapy
has been used when there is regrowth after subtotal or radical subtotal
removal and with small tumors which start to enlarge in older patients
who are being observed.
I use the supine position with the
ipsilateral shoulder slightly elevated and the head turned to the
opposite side. The details have been described (47) (see
Chap. 24). This approach has worked well for visualization of
the important anatomical structures, tumor removal, comfort of the
operator, and avoidance of problems with air embolism or hypotension.
Guthrie et al. (26) described a similar approach. Other surgeons
have used the sitting position and achieved good results (58, 65,
The key considerations in the operation
- Exposure of the tumor as described
in Chap. 23.
- Interruption of the blood supply
along the dural attachments.
- Internal decompression combined
with careful dissection of the tumor capsule from the brainstem
and cranial nerves.
There were 57 patients with cerebellopontine
angle meningiomas, 37 women and 20 men, ranging in age from 38 to
89 years, with 10 over 70 years of age (Table 17.16). In the 42
patients listed in Table 17.16, Anterior, the tumor arose anterior
to the internal auditory meatus in 27 and anterior-inferior in 10
and grew diffusely in five. The extent of the tumor removal is recorded
in Table 17.16. In only 14 patients could I be sure of a total removal
but in another 10 a radical subtotal removal was done. On follow-up,
34 of the 42 patients had a good result, three had a fair result
because of postoperative disability, four had poor results because
of severe preoperative neurological disabilities that did not significantly
improve, and there was one postoperative death. This occurred
in an 89-year-old man who had been well
until he started to develop worsening ataxia. CT showed a 4-cm tumor
with hydrocephalus. A shunt was placed, with improvement, but several
months later symptoms of brainstem compression worsened. A subtotal
removal was done but the patient died of a cardiopulmonary complication.
|TABLE 17.16 Cerebellopontine
aT, total removal
RST, radical subtotal removal
ST, subtotal removal
bGood, free of major
neurological deficit and able to return to previous activity
Fair, independent but not able
to return to full activity because of new neurological
deficit or significant preoperative deficit that did not fully
None of the patients with radical
subtotal removal has shown recurrence and all have been followed
by scans. Most of the patients with subtotal removal had large tumors
(>3 cm). Three were growing anteriorly into the middle fossa.
After subtotal removal, 15 of 18 had follow-up scans, which showed
no growth in eight, slight growth in five (three of whom have been
given radiation therapy and two of whom are being observed after
showing no further growth on subsequent scans), and moderate growth
in two of the disabled patients, where nothing further has been
Postoperative complications included
permanent increased ataxia in three, one of whom had to have a cerebellar
infarction removed, one patient with wound infection and meningitis,
and one with a cerebrospinal fluid leak requiring repair. Several
patients had temporary increases in ataxia, incoordination, or swallowing
problems which improved. Four patients had a shunt for hydrocephalus
at some time in their course.
Of the 15 patients with meningiomas
arising posterior to the internal auditory meatus, 13 had a total
removal (Table 17.16). One had a radical subtotal and one a subtotal
removal because of involvement of the lower cranial nerves. All
had a good result. There were no postoperative neurological complications
and no recurrences.
Yasargil et al. (79) reported that
27 of 30 patients had a good result and in 27 the tumor was "radically
excised." Sekhar and Jannetta (65) reported total removal in
14 of 22 patients, with no operative mortality and a good outcome
in 16. Samii and Ammirati (58) reported total removal of all 24
tumors located posterior to the internal auditory meatus, with a
good outcome for 22 patients. Of 32 patients with tumors anterior
to the internal auditory meatus, 29 had the tumors totally removed
and 28 had a good outcome.
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