Falcotentorial meningioma, Medycyna, Neurochirurgia - podręczniki
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J Neurosurg 104:
47–53, 2006
Falcotentorial meningioma: surgical outcome in 14 patients
T
AKEO
G
OTO
, M.D., K
ENJI
O
HATA
, M.D., M
ICHIHARU
M
ORINO
, M.D.,
T
OSHIHIRO
T
AKAMI
, M.D., N
AOHIRO
T
SUYUGUCHI
, M.D., A
KIMASA
N
ISHIO
, M.D.,
AND
M
ITSUHIRO
H
ARA
, M.D.
Department of Neurosurgery, Osaka City University Graduate School of Medicine, Osaka, Japan
Object.
The authors evaluated their surgical experience over 20 years with 14 treated falcotentorial meningiomas.
Methods.
In the past 20 years, 14 patients with falcotentorial junction meningiomas were surgically treated. There
were seven men and seven women, whose ages ranged from 34 to 79 years. On the basis of neuroimaging studies, the
authors analyzed the influence of the anatomical relationship of the tumor to the vein of Galen, patency of the vein of
Galen, tumor size, and the signal intensities on the magnetic resonance images to determine possible difficulties that
might be encountered during surgery and to prognosticate the outcome of surgery. Depending on the relationship with
the vein of Galen, tumors were labeled as either a superior or an inferior type. All tumors were resected via an occip-
ital transtentorial approach.
The surgical outcome in eight patients was excellent; in the remaining six patients, it was fair. Of the prognostic fac-
tors, tumor location especially seemed to be the most important (p
,
K
EY
W
ORDS
• meningioma • falcotentorial junction • galenic system
ENINGIOMAS
arising from the falcotentorial junction
are relatively rare, and only isolated case reports or
small series related to surgical technique are avail-
able in the literature.
1,5,7,8,11–13,16
Because of the lesion’s depth
from the surface and its anatomical proximity with critical
neural and vascular structures, surgical access and tech-
nique are complex issues. A variety of factors influence
surgery and outcome. In this paper, on the basis of our expe-
rience, we analyze a set of factors to determine which prob-
ably influence surgical outcome.
achieved in 11 patients, and subtotal tumor removal in three.
Among the 11 patients, eight had no postoperative neuro-
logical worsening except for transient hemianopia; the oth-
er three patients experienced postoperative permanent neu-
rological deterioration, including memory disturbance and
hemianopia. Among the three patients who had undergone
a subtotal tumor removal, no neurological deterioration oc-
curred postoperatively. Surgical outcome was graded as sat-
isfactory in eight patients (Cases 1–8) given that the tumors
had been totally removed and there was no permanent neu-
rological deterioration. Outcome was unsatisfactory in six
patients (Cases 9–14) because either the lesions were not to-
tally removed or the patients had permanent functional dete-
rioration following total tumor removal.
Clinical Material and Methods
Patient Population and Tumor Characteristics
During the years between 1984 and 2004, 14 patients
with falcotentorial junction meningiomas were surgically
treated at our institution by the two senior surgeons (A. Ha-
kuba and K.O.). Pineal region meningiomas that did not
have a dural base in the falcotentorial region were not in-
cluded in this series. There were seven men and seven wom-
en whose ages ranged from 34 to 79 years (mean 57 years;
Table 1). The chief presenting symptoms included severe
headache in five, memory disturbance in five, gait distur-
bance in two, and tinnitus in two patients. All tumors were
exposed via an occipital transtentorial approach. The side of
the surgical approach was dependent on the predominant
side of tumor extension. Four tumors were approached on
the right side and five on the left. In five tumors the ap-
proach was bilateral because the tumor extended widely on
both sides of the midline. Total resection of the tumor was
Analysis of Prognostic Factors
Preoperative neuroimaging investigations included MR
imaging, MR venography, and angiography. Apart from
evaluating the physical characteristics of the tumor, we
evaluated the relationship of the tumor to the great vein of
Galen, the patency of the vein of Galen, and the straight si-
nus. Depending on the relationship of the tumor to the great
vein of Galen, tumors were classified into two types: tumors
located superior to the vein and compressing it downward
were labeled as the superior type, whereas those displacing
it superiorly were labeled as the inferior type (Fig. 1).
To evaluate prognostic factors, preoperative neuroimag-
ing findings and surgical findings were analyzed in eight
patients (Cases 1–8) with satisfactory outcomes and six
(Cases 9–14) with unsatisfactory outcomes. Neuroimag-
ing findings were statistically compared between these two
groups.
Abbreviation used in this paper:
MR = magnetic resonance.
J. Neurosurg. / Volume 104 / January, 2006
47
0.01, Fisher exact test). The outcome associated
with the inferior type of tumor was significantly less optimal probably due to the relationship to the deep veins and the
brainstem. In this series, the occlusion of deep veins did not significantly influence outcome.
Conclusions.
Classification of the tumor location by preoperative neuroimaging studies can be helpful in estimat-
ing the surgical difficulty that might be encountered in treating the falcotentorial junction meningioma.
M
T. Goto, et al.
TABLE 1
Summary of characteristics in 14 patients with falcotentorial junction meningiomas
Case
Age (yrs),
Chief
Extent of
Follow Up
Outcome
No.
Sex
Symptom
Tumor Removal
Complications
(mos)
Group
1
49, F
headache
total
none
238
satisfactory
2
50, F
headache
total
none
221
satisfactory
3
55, F
memory disturbance
total
none
220
satisfactory
4*
54, M
memory disturbance
total
none
217
satisfactory
5
47, M
headache
total
transient hemianopia
187
satisfactory
6
63, M
memory disturbance
total
none
90
satisfactory
7
34, M
tinnitus
total
none
70
satisfactory
8
69, M
headache
total
none
51
satisfactory
9
69, F
memory disturbance
total
deterioration of memory
126
unsatisfactory
& hemianopia
10
49, F
headache
total
hemianopia
72
unsatisfactory
11
62, F
gait disturbance
total
memory disturbance
60
unsatisfactory
12
79, M
gait disturbance
subtotal
none
50
unsatisfactory
13
57, F
tinnitus
subtotal
none
41
unsatisfactory
14
61, M
memory disturbance
subtotal
none
38
unsatisfactory
* The MR imaging unit was not used before surgery in this case.
Results
Neuroimaging characteristics and surgical results are
summarized in Table 2. In the satisfactory-outcome group
(Cases 1–8), the tumor did not tightly adhere to the straight
sinus, deep veins (great vein of Galen and basal vein), col-
lateral venous channels, or brainstem. Only one patient
(Case 3) required suturing of the injured venous wall at a
single point during surgical procedures. This situation en-
abled the surgeons to remove the tumor totally without sur-
gical complication. On the other hand, in the three cases
(Cases 9–11) in which there was an unsatisfactory outcome,
there was tight adhesion or proximity between the tumor
and collateral venous channels of the deep veins. In all of
these three cases, there was intraoperative injury to the deep
veins or collateral veins during resection of the tumor. All
of these patients suffered postoperative venous infarction
associated with memory disturbance and hemianopia. The
cause of memory disturbance was unclear, although it was
presumed to be due to postoperative dysfunction of the left
mesial temporal lobe structures, which was related to com-
promise of the left basal vein of Rosenthal or the left inter-
nal cerebral vein.
Based on the lessons learned from our experience with
the initial three cases, a small amount of the tumor was left
behind to avoid injury to the deep veins, collateral veins,
and brainstem in the subsequent three cases (Cases 12–14).
Tumor Location Related to the Great Vein of Galen
In the satisfactory-outcome group, seven tumors were
classified as the superior type and one tumor as the inferi-
or type. On the other hand, in the unsatisfactory-outcome
group all six tumors were classified as the inferior type. The
location type was significantly different between the two
outcome groups (p
,
0.01, Fisher exact test).
Occlusion of the Great Vein of Galen and the
Straight Sinus
In the satisfactory-outcome group, preoperative inves-
tigations suggested occlusion of the great vein of Galen in
one case and of the straight sinus in another case. In the
unsatisfactory-outcome group, there were three cases of ve-
nous occlusion, one of which involved occlusion of the
straight sinus and two of which involved occlusion of both
the great vein and the straight sinus. Preoperative inves-
tigations in all cases with venous occlusion in both out-
come groups demonstrated well-developed collateral ve-
nous channels. Occlusion of the great vein of Galen and the
straight sinus did not significantly influence surgical out-
come (p = 0.34, Fisher exact test).
Tumor Size
Tumor size ranged from 22 to 58 mm (mean 38.6 mm).
In the satisfactory-outcome group, tumor size was signifi-
cantly larger than that in the unsatisfactory-outcome group
(mean
6
standard deviation, 44
6
9.4 mm compared with
31.3
6
6.1 mm; p
,
0.05, Welch t-test).
F
IG
. 1. Ilustration demonstrating the location type of the tumor.
A tumor located over the vein of Galen and compressing it down-
ward was classified as the superior type, and one situated under the
vein of Galen and dislocating it upward was the inferior type.
Magnetic Resonance Imaging Intensity of the Tumor
Eleven patients underwent MR imaging studies before
48
J. Neurosurg. / Volume 104 / January, 2006
Falcotentorial meningioma
TABLE 2
Neuroimaging characteristics and surgical findings in 14 patients with falcotentorial junction meningiomas*
Occlusion of Deep Veins
Surgical Findings
Vein
Tumor MRI Signal Intensity
Injuy to Deep
Suturing
Outcome
Case
Tumor
of
Straight
Size
or Collateral
of Vein
Group
No.
Locationâ€
Galen
Sinus
(mm)â€
T
1
T
2
â€
Veins
Wall
satisfactory
1
superior
2
2
45
NE
NE
2
2
satisfactory
2
superior
2
1
40
NE
NE
2
2
satisfactory
3
superior
2
2
50
NE
NE
1
1
satisfactory
4‡
superior
2
2
58
iso
high
2
2
satisfactory
5
superior
2
2
32
iso
high
2
2
satisfactory
6
superior
2
2
32
iso
high
2
2
satisfactory
7
inferior
2
2
42
iso
high
2
2
satisfactory
8
superior
1
2
53
iso
high
2
2
unsatisfactory
9
inferior
1
1
31
iso
low
1
1
unsatisfactory
10
inferior
2
2
27
iso
iso
1
1
unsatisfactory
11
inferior
2
1
38
iso
low
1
1
unsatisfactory
12
inferior
1
1
40
iso
low
2
2
unsatisfactory
13
inferior
2
2
30
iso
iso
2
2
unsatisfactory
14
inferior
2
2
30
low
high
2
2
= patent.
†This prognostic factor significantly influenced surgical outcome.
‡ The MR imaging unit was not used before surgery in this case.
1
= occluded;
2
the operation; three patients were treated before the era of
MR imaging. On T
1
-weighted MR images, all tumors in the
satisfactory-outcome group and five of six tumors in the
unsatisfactory-outcome group appeared isointense. Signal
intensity on T
1
-weighted images was not significantly dif-
ferent between the two outcome groups (p = 0.68, Mann–
Whitney U-test). On T
2
-weighted MR images, four tumors
were hyperintense and one was isointense in the satisfacto-
ry-outcome patients. In the unsatisfactory-outcome group,
the tumor was hyperintense in one case, isointense in two
cases, and hypointense in three cases. The T
2
-weighted sig-
nal was significantly greater in the satisfactory-outcome
group than that in the unsatisfactory-outcome group (p
,
the falcotentorial junction. The size of the tumor was 53
mm in its maximal diameter. On an angiogram and a MR
venogram, the tumor was located over the vein of Galen and
dislocated it downward and was classified as the superi-
or type. The vein of Galen was occluded at the point of en-
try into the straight sinus, and the deep venous flow drained
through the collateral venous channels into the petrosal vein
and the transverse sinus. The tumor was excised via an oc-
cipital transtentorial approach. The tumor had a well-de-
fined plane of dissection from the brainstem, vein of Galen,
straight sinus, and collateral veins. The tumor could be to-
tally removed and there was no postoperative complication
(Fig. 2).
Case 13.
This 57-year-old woman, who had presented
with a 2-month history of tinnitus, harbored an inferior type
of falcotentorial meningioma. Although the size of the tu-
mor was not very large (22 mm in its maximal diameter), it
was tightly adhered to the great vein of Galen and basal
veins. A small portion of the tumor was left behind around
these veins to avoid venous damage (Fig. 3). Postoperative-
ly, there was no neurological worsening.
Illustrative Cases
Case 8.
This 69-year-old man presented with a 3-month
history of gradually progressing severe headache. There
was no neurological deficit at the time of admission.
Magnetic resonance imaging demonstrated a large mass at
F
IG
. 2. Case 8. a: Preoperative sagittal contrast-enhanced T
1
-weighted MR image demonstrating a superior type tu-
mor. b: An MR venogram demonstrating the anatomical relationship between the vein of Galen and the tumor. c: Post-
operative sagittal contrast-enhanced T
1
-weighted MR image showing total removal of the tumor.
J. Neurosurg. / Volume 104 / January, 2006
49
* Iso = isointense; NE = not evaluated;
0.05, Mann–Whitney U-test).
T. Goto, et al.
F
IG
. 3. Case 13. a: Preoperative sagittal contrast-enhanced T
1
-weighted MR image revealing an inferior type tumor.
b: An MR venogram showing the anatomical relationship between the vein of Galen and the tumor. c: Postoperative sag-
ittal contrast-enhanced T
1
-weighted MR image demonstrating partial removal of the tumor.
Discussion
Our study data suggested that the tumor location in rela-
tion to the great vein of Galen was the most significant
prognostic factor in surgery for the falcotentorial junction
meningioma. Occlusion of the galenic system, however,
was not an indicator of excellent surgical outcome. The size
of the tumor was not necessarily a prognostic factor given
that all of the large tumors in our series were the superior
type, could be totally resected, and were associated with a
satisfactory outcome. Concerning the MR imaging signal
intensity, it is clear that the softer meningiomas can be more
easily removed than the firmer ones.
A review of the literature demonstrates that preexisting
occlusion of the galenic system and the subsequent de-
velopment of collateral venous circulation is an important
factor when considering surgery on pineal region tumors,
including falcotentorial junction meningiomas.
1,3,9,10,14
In
such a situation, however, the collateral venous flow must
be preserved.
1,7
In the present study in cases of the inferior
type tumor with an occluded galenic system, dissecting the
tumor from surrounding collateral veins and brainstem was
relatively difficult technically. Resection of the tumor in
such cases led to damage of the surrounding structures with
additional neurological deficits. It appeared that in cases in
which the galenic venous system was patent, the surgical
procedure was more difficult because the tumor was tightly
adhered to the venous system. To prevent injury to the deep
vein, a small amount of the tumor can be left behind around
the deep veins to avoid their injury in the context of an infe-
rior type tumor. It was observed that in the case of the supe-
rior type tumor, even when the vein of Galen was patent, a
careful surgical technique enabled the surgeon to separate
the tumor from the vein of Galen. As a result, complete sur-
gical removal could be relatively safely performed in the
case of superior type tumors.
Several types of collateral venous channels developed as
a result of occlusions of the galenic system. Based on our
study data, it appears that collateral channels under the thick
arachnoid septum might be the most functionally and sur-
gically important collateral veins in surgery for the infe-
rior type tumor, because the tumor tends to adhere to all of
the galenic system including possible collateral veins in the
same cistern.
To evaluate the importance of tumor location as a prog-
nostic factor, we reviewed the literature on falcotentorial
junction meningiomas from the past 20 years and found 24
cases to which we could apply our classification system of
tumor location on the basis of neuroimages and lesion de-
scriptions (Table 3).
1,5,7,8,11–13,16
Of the 38 cases—that is, 14
from the present study and 24 from the literature—18 were
included in the satisfactory-outcome group and the other 20
TABLE 3
Relationship between tumor location and surgical
outcome in 38 cases
No. of Patients
Authors &
Tumor
factory
Unsatis-
Year
Location
Outcome
Outcome
Suzuki, et al., 1984
superior
1
0
inferior
0
0
Odake & Goel, 1992
superior
0
1
inferior
0
1
Sekhar & Goel, 1992
superior
0
0
inferior
0
1
Asari, et al., 1995
superior
2
0
inferior
2
2
Matsuda & Inagawa,
superior
1
1
1995
inferior
0
1
Samii, et al., 1996
superior
0
0
inferior
2
4
Ziyal, et al., 1998
superior
1
0
inferior
0
1
Okami, et al., 2001
superior
1
2
inferior
0
0
present study
superior
7
0
F
IG
. 4. Graph showing the relationship between the tumor loca-
tion type and surgical outcome. The location of the tumor was sig-
nificantly different between the two outcome groups (p
inferior
1
6
total
18
20
,
0.01).
50
J. Neurosurg. / Volume 104 / January, 2006
Satis-
factory
Falcotentorial meningioma
F
IG
. 5. Drawings depicting the growing process of the superior type falcotentorial junction meningioma. a: The supe-
rior type tumor is originally located in the posterior pericallosal cistern. b: As the tumor increases in size, it pushes down
the quadrigeminal cistern, including the vein of the Galen and basal veins. The tumor and deep veins are in different cis-
terns. There is a thick arachnoid membrane between them.
in the unsatisfactory-outcome group. In the satisfactory-out-
come group, 13 tumors were classified as the superior type
and the other five as the inferior type. In the unsatisfactory-
outcome group, four tumors were categorized as the superi-
or type and the other 16 as the inferior type. Based on our
experience with the cases in our study and those reported in
the literature, it appears that there is a significant difference
in surgical outcome between superior and inferior types of
tumor locations (p
omy, the thick broad arachnoid membrane, extending from
the tentorial ridge to the splenium, clearly separates the pos-
terior pericallosal cistern from the quadrigeminal cistern,
which includes the great vein of Galen, basal veins, and dor-
sal midbrain.
2,4,6,15
It is most likely that the superior type tu-
mor, growing inside the posterior pericallosal cistern, might
compress deep veins over the arachnoid membrane. In this
situation, thick arachnoid membrane septum between two
cisterns protects the deep veins from direct tumor invasion,
which enables the surgeon to dissect the lesion from the
deep veins (Fig. 5). On the other hand, the inferior type tu-
mor, growing in the quadrigeminal cistern, might compress
the deep veins and dorsal midbrain in direct contact with
J. Neurosurg. / Volume 104 / January, 2006
51
0.01, Fisher exact test; Fig. 4).
The reason for the relative difficulty in surgical removal
and outcome between superior and inferior types of tumors
could be due to the relationship of the arachnoid membrane
to the deep veins, brainstem, and tumor. In the normal anat-
,
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