Current Otorhinolaryngology Reports (2019) 7:65–72
https://doi.org/10.1007/s40136-019-00230-4
OTOLOGY: TUMORS OF THE EAR AND LATERAL SKULL BASE (G DANESI, SECTION EDITOR)
The Transpetrosal Approaches System in Posterior Fossa Meningiomas
Surgery: Rationale and Results
Roberto Pareschi 1 & Giovanni Danesi 2 & Roberto Stefini 3 & Rachele Bivona 2 & Catalina Iglesias Valera 2
Published online: 1 February 2019
# Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
Purpose of Review This is a retrospective review of 90 patients with a posterior fossa meningioma (PFM) treated between 1996
and 2017 in our two tertiary skull base centers. Patients underwent surgical resection via different approaches. We aimed to show
how different surgical approaches may help to reach gross total resection (GTR) and low morbidity, especially on facial nerve
function.
Recent Findings PFM is a real surgical challenge with high morbidity and mortality due to the surrounding structures, their
common large size at diagnosis, and their potentially invasive behavior. Total resection is the only way to cure people affected.
We successfully treated 90 cases of PFM and evaluated different surgical approaches.
Summary GTR is the aim of the surgery as the extent of resection influences the rate of recurrence, which in turn influences the
prognosis. Seventy percent (p < 0.001) of surgical patients achieved a GRT with low morbidity and no mortality.
Keywords Posterior fossa meningioma . Transpetrosal approaches . Combined petrosal . Gross total resection . Meningioma
surgery . Cerebellopontine angle tumors
Introduction
Meningiomas account for 20 to 25% of all intracranial tumors
and 10% are seen in the posterior fossa. Posterior fossa meningioma (PFM) is the second most common tumor in the
cerebellopontine angle, accounting for 10 to 15% of neoplasms in this area [1]. PFM is a real surgical challenge with
high morbidity and potential mortality due to the surrounding
vital structures, the encasement of nerves and vessels, the
common large size at diagnosis, and their potentially invasive
behavior. The decision on the necessity of complete surgical
resection remains critical. They are benign tumors commonly
This article is part of the Topical Collection on OTOLOGY: Tumors of the
Ear and Lateral Skull Base
* Roberto Pareschi
rpareschi@inwind.it
1
Ospedale Nuovo di Legnano, ENT & Skull Base Department, via
Papa Giovanni Paolo II, Legnano 20025, MI, Italy
2
Ospedali Riuniti di Bergamo, ENT & Skull Base Department,
Bergamo, Italy
3
Ospedale Nuovo di Legnano, Neurosurgical Unit, via Papa Giovanni
Paolo II, Legnano 20025, MI, Italy
seen in adults, which usually present after a long asymptomatic period. The natural history of these lesions suggests progressive growth with progressive neurological deterioration
until death [1, 2].
Though they make up a relatively small proportion of
cerebellopontine angle (CPA) tumors, PFM is particularly interesting because their management issues differ somewhat
from acoustic nerve tumors. Management problems can be
much less or much greater depending on the point of the
petrous bone (PB) from which they arise [3]. The aim of this
report is to present our experience and surgical strategies in the
management of PFM.
Patients and Methods
The study was approved by the respective Ethics Committee
and patient consents were obtained.
This is a retrospective review of all our patients with posterior fossa meningiomas treated between 1996 and 2017 in
our two tertiary skull base centers (Legnano and Bergamo,
Italy) as we share the same philosophy in terms of management and surgical treatment. Epidemiological and clinical data, surgical and histological reports, preoperative and
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Curr Otorhinolaryngol Rep (2019) 7:65–72
postoperative images, complications, data on adjuvant therapy, and follow-up information were reviewed.
Between 1996 and 2017, 90 patients were treated for a
posterior fossa meningioma and were included in the present
analysis. They were 19 male and 71 female with age ranging
from 23 to 74 years old.
Meningiomas were divided into three groups according to
their correlation with the internal auditory canal (IAC):
retromeatal, perimeatal, and premeatal.
The foramen magnum, jugular foramen, and tentorial meningiomas were excluded from this survey along with
intrameatal tumors with a CPA protrusion less than 10 mm.
Statistical analysis was performed using SPSS version 17.0
for Windows (SPSS Inc., Chicago, IL); categorical variables
were compared using the chi-square, P values of less than 0.05
were regarded as statistically significant.
Classification
Tumor location was determined after a careful examination of
the preoperative radiological images (CT-MRI) along with the
intraoperative remarks. The meningiomas were classified into
retromeatal, perimeatal, and premeatal, according to the relationship between the main dural attachment and the IAC. The
site of the displacement of the acoustic-facial bundle, depending on the dural origin of the tumor, was the utmost important
factor determining the surgical complexity and the surgeryrelated morbidity. We distinguished 21 meningiomas with a
main dural attachment posterior to the internal auditory canal
(retromeatal meningiomas), 19 meningiomas in the contest of
IAC and 50 meningiomas with dural attachment anterior to
the internal auditory canal (premeatal meningiomas) (Table 1).
Retromeatal meningiomas (posterior PB meningiomas)
originate from the dura of the posterior PB, between the posterior wall of the IAC and the groove of the sigmoid sinus.
They occupy the posterior part of the cerebellar-pontine angle
(PCA) usually dislocating anterosuperiorly the acoustic-facial
bundle. Eight meningiomas of this group presented an
inframeatal extension encroaching the jugular foramen. In
two cases, the tumor extended extracranially into the neck.
In 18 cases, the dural attachment involved the tentorium with
a transtentorial extension.
Perimeatal meningiomas arise from the dura in the contest
of IAC and they do not dislocate anteriorly or posteriorly.
Table 1 Meningiomas’
classification
Surgical Approaches
The selection of surgical approach (Table 2) was tailored according to the location and the extension of the tumor and on
the basis of patient factors, such as age, general health, preoperative cranial nerve dysfunction, and preoperative hearing.
We focused our attention on the location of the tumor’s
main insertion site, the involvement of the adjacent structures,
and the tumor size. Prediction of the nerve displacement, with
particular attention to the acoustic-facial bundle, was a key
factor in our decision.
For retromeatal meningiomas, the surgical approaches
were: retrosigmoid (RS), translabyrinthine (TLab), petrooccipital-transigmoid (POTS), and retrolabyrinthinesubtemporal (RLabST).
–
The RS approach was indicated in all cases with a normal
or socially useful preoperative hearing (class A or B of
Tokyo Classification)3. The size and the intrameatal extension of the tumor did not influence the choice of this
approach. A standard lateral RS approach with the patient
in park-bench position was used in this group. The RS
approach is a versatile type of craniotomy extending from
the sigmoid and the transverse sinus to the occipital squama. Opening of the dura and retraction of cerebellum
gives wide access to the CPA after early drainage of the
cerebellomedullary cistern. Retrolabyrinthine meatotomy
allows exposure of the IAC for the removal of the
Table 2 Selection of surgical approach according to the location and the
extension of the tumor
Retromeatal
Retromeatal 21/90
Perimeatal 19/90
Premeatal 50/90
Premeatal meningiomas (anterior PB meningiomas) arise
from the dura around the porus trigeminalis (petrous apex
(PA) meningiomas) or from the dura of the petroclival (PC)
junction or directly from the clivus (PC meningiomas). They
occupy the anterior part of the CPA and dislocate
posteroinferiorly the acoustic-facial bundle immediately behind the dura of the posterior PB. Premeatal meningiomas
are more difficult to remove because the cranial nerves are
located between the surgeon and the tumor. Fifteen meningiomas of this group presented a tentorial or a transtentorial
extension, with the invasion of the Meckel cave in 11 cases,
and in nine cases, the invasion of the cavernous sinus, upper
clivus, and middle cranial fossa was evident.
Petrous apex 19/50
Petro-clival 25/50
Clival 6/50
Premeatal
Perimeatal
RS
9
TLabTAp
20
TLab
POTS
RLabST
7
3
2
TC
TLab+FAR lateral
Combined petrosal
18
1
11
TLab
19
Curr Otorhinolaryngol Rep (2019) 7:65–72
–
–
–
–
intrameatal extension of the tumor with a high rate of
hearing preservation.
The TLab approach is indicated in all the cases with a
significant deterioration of the hearing or anacusia (class
C, D, or E of Tokyo classification) [3] or in elderly patients with huge symptomatic tumors. The access to this
approach is the mastoid and the target is the IAC and
CPA. After a wide conservative mastoidectomy is performed, the occipital pre- and retrosigmoid dura along
with the dura of the temporal lobe are exposed thus
allowing for the retraction of sigmoid sinus with a significant widening of the surgical field. The posterior wall of
the external auditory canal, the tympanic cavity, the cochlea, and the facial nerve are left in place. The posterior
labyrinth is completely drilled out together with the bone
that is lateral, superior, and inferior to the IAC. The canalicular dura is completely uncovered until the fundus and
the facial nerve entering in the fallopian canal is evident.
Once the approach is performed, the jugular bulb is the
inferior limit and the temporal dura with the superior petrous sinus are the superior limits. The presigmoid dura is
transected and the CPA is widely exposed.
The POTS approach has been developed for removing tumors situated in the jugular foramen together
with their local extension into the adjacent parts of
the skull base, the CPA, and the parapharyngeal
space (PPS). POTS approach involves a posterolateral exposure and an anteromedially directed surgical axis which allows the surgeon to leave the external and middle ear complex, together with the
facial nerve, entirely undisturbed. Single-stage removal of intra- and extradural lesions extending
from the CPA to the PPS can be achieved with
minimal risk of cerebrospinal fluid (CSF) leak. In
essence, the POTS approach is the combination of a
retrolabyrinthine petrosectomy and retrosigmoid craniotomy. The external ear canal, tympanic cavity,
and facial nerve are left in situ [4].
The RLabST is one of the most minimal of the
transpetrosal approaches of the posterior fossa. After a
wide conservative mastoidectomy is performed, the sigmoid sinus is skeletonized inferiorly through the
infralabyrinthine air cells to the jugular bulb. Complete
skeletonization of the facial nerve is unnecessary. All
three semicircular canals are, therefore, skeletonized but
preserved. Removal of the bone plates on the middle and
posterior fossa dura mater and the sigmoid sinus completes the extradural part of the retrolabyrinthine approach. This approach provides exposure of the CPA
but does not give the surgeon adequate visualization of
the anterior brain stem or petroclival region [5].
For perimeatal meningiomas, the TLab surgical approach
was performed.
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–
–
–
–
For premeatal meningiomas, the surgical approaches performed were mainly the translabyrinthine/transapical approach (TLabTAp) and the transcochlear approach (TC),
only one case initially treated with a TLab surgery then
requested a far-lateral approach; in 11 cases, combined
petrosal approaches were performed.
The TLabTAp is an anterior extension of the TLAb in
which the internal auditory canal is exposed 360° around
its circumference. The cornerstone of this approach is the
posteroinferior transposition of the acoustic-facial bundle
in continuity with the intracisternal tract that, for
premeatal meningiomas, is usually located in the interface
between the posterior PB dura and tumor. This maneuver
respects the functional integrity of the facial nerve (if it is
not infiltrated by the tumor) allowing for the complete
drilling out of the bone and the exposure of the dura
around the porus trigeminalis (PA). The posteroinferior
dislocation of the acoustic-facial bundle opens a corridor
to the anterior CPA through which the removal of large
PA and PC meningiomas is possible. The limit of this
access is the midline extension of the tumor. An extension
beyond this line should be treated by a TC.
The TC represents the widest available access to the
posterior fossa. It allows for the exposure of the
omolateral CPA, prepontine area, and contralateral
CPA. This approach is indicated for giant PA, PC, or
clival meningiomas, extending beyond the midline and
between the clivus and the pons. Compared with the
TLabTAp, it presents some additional surgical steps:
(1) the removal of the outer ear canal and tympanic
cavity with closure of the external ear canal; (2) total
petrosectomy extended to the middle and lower clivus
located medially to the cochlea and the vertical tract of
the petrous internal carotid artery (ICA); (3) the
postero-inferior transposition of the intratemporal facial nerve along with its intrameatal tract. This maneuver does not allow the functional integrity of the facial
nerve. After surgery, a grade III facial palsy (according
to the House Brackmann Classification [6]) is the best
result that can be obtained and this is the most important drawback of this approach.
Combined petrosal approaches actually describe numerous surgical approaches to the petroclival area well suited
for these tumors. The transtentorial step was necessary in
ten of them where the dura of the middle fossa above the
superior aspect of the petrosal bone and the tentorium
over the trigeminal nerve are resected. Indications to
transtentorial approach are: lesion extending from PF to
the midbrain, lesion extending from middle fossa to PF,
and lesions arising from the tentorium.
Transpetrous approaches have important advantages when
compared to the RS approaches:
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Table 3 Main tumors’
residuals
Curr Otorhinolaryngol Rep (2019) 7:65–72
Transtentorial 18
Jugular foramen 8
Gasser 1
Cavernous sinus 1
1) The wide surgical field, a shorter working distance between the craniectomy and the tumor and a better orientation towards the lateral and ventral brain stem, limiting
the brain retraction.
2) The early resection of the osteo-dural insertion of the
meningioma, with coagulation of the tumor’s feeding
vessels.
3) The early identification and control of the facial nerve
before any dissection or removal of the tumor, and increased protection of the anatomical and functional integrity of the facial nerve (except for the TCA)
4) After the dura is opened or resected, the next step is to
obtain an optimal internal debulking, followed by the peripheral dissection, with special attention to the identification and preservation of the neurovascular structures.
The main disadvantages of the transpetrous approaches are
that they require a dedicated long-lasting training together
with a deep knowledge of the complex anatomy of the PB.
Moreover, the intrapetrous otoneurological structures are at
risk for damage during the approach.
Results
Ninety patients underwent surgical resection via different approaches as the tumors extended into different directions,
mainly towards the petrous apex.
Extension and Surgical Approach Twenty-one (23.3%) patients harbored a retromeatal tumor whereas a perimeatal meningioma was found in 19 patients (21.1%) and a premeatal
meningioma in 50 patients (55.5%) of which 19 extended to
the petrous apex (38%) cases, petro-clival region in 25 (5%)
cases, and the clivus in six (12%) cases (Table 1).
A transtentorial extension was evident in 18/90 cases
(20%) and the jugular foramen was involved in 8/90 cases
(8.8%); the gasser ganglion and the cavernous sinus were
respectively involved in one case (1%) (Table 3). Those represent the main tumors’ residuals.
For the retromeatal meningiomas, a RS approach was performed in nine cases (42.8%), a TLab approach in seven cases
(33%), the POTS approach in three cases (14%), and RLabST
in two cases (9%). For the perimeatal meningiomas, a TLab
approach was performed in all the cases. For the premeatal
meningiomas, the TLabTAp approach was performed in 20
cases (40%), the TC approach in 18 cases (36%), and a combined petrosal approach was performed in 11 cases (22%) of
which a transtentorial phase was necessary in ten cases
(Table 2).
Preoperative Symptoms Preoperative symptoms were significantly related to tumor location. Trigeminal symptoms
(dysesthesia and neuralgia) and abducent nerve palsy were
more frequent in premeatal and perimeatal groups, hearing
and vestibular symptoms predominantly occurred in association with retromeatal and perimeatal tumors. Others symptoms like headache and cerebellar signs had a similar distribution between the premeatal and retromeatal groups. (Table 4).
Tumor Resection The extent of tumor resection was defined
by the intraoperative findings using the Simpson classification
[7]. These findings were confirmed by the postoperative MRI
with gadolinium at 3 months’ and 1-year’ time. The Simpson
grades 1 and 2, with no evidence of persistence at the postoperative MRI, corresponded to a GTR. Simpson grade 3, 4, or
5, confirmed by the evidence of residual tumor at the postoperative MRI, are related to a non-total resection (near total or
partial resection).
GTR was achieved in 69/90 patients, 77% (p < 0.001).
More specifically, in retromeatal meningiomas, a total resection was obtained in 20/21 cases (95%). In perimeatal meningiomas, GTR was obtained in all cases (19/19). In premeatal
meningiomas, GTR was lower, 38/50 (76%) patients,
reflecting the more difficult surgical treatment of these tumors.
A grade 3 (NTR) was evident in 4/90 patients (4%), and
grades 4–5 (PTR) in 9/90 patients (10%) (Table 5).
Table 4 Preoperative symptoms
Trigeminal signs
Cerebellar signs
VI C.N. palsy
Hearing loss, tinnitus, vertigo
Hydrocephalus
Headache
Retromeatal
Premeatal
Perimeatal
1/21 (4.7%)
6/21 (28.5%)
0/21 (0%)
8/21 (38%)
1/21 (4.7%)
4/21 (19%)
18/50 (36%)
7/50 (14%)
2/50 (4%)
12/50 (24%)
2/50 (4%)
6/50 (12%)
6/19 (31.5%)
0/19 (0%)
0/19 (5.2%)
12/19 (63.1%)
0/19 (0%)
1/19 (5.2%)
Curr Otorhinolaryngol Rep (2019) 7:65–72
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Table 5 Extent of tumor
resection
Description
Retromeatal
Premeatal
Perimeatal
Simpson grade 1–2
GTR (p < 0.001)
20/21 (95.2%)
38/50 (76%)
19/19 (100%)
Simpson grade 3
NTR
0/21 (0%)
4/50 (8%)
0/19 (0%)
Simpson grade 4–5
PTR
1/21 (4.7%)
8/50 (16%)
0/19 (0%)
The consistency, bleeding, and adherence of the tumor to
the brain stem and to vessels prevented their total removal,
permitting only brain-stem decompression. According to the
surgical approach, a GTR (Simpson Grade 1–2) was achieved
in 69/90 (77%). (Table 6).
Morbidity Previous studies have emphasized the less important morbidity regarding auditory and facial function in
retromeatal meningiomas compared with anteriorly based tumors (Table 7).
Retromeatal tumors represented the more accessible tumors in our series. A postoperative HB grades I–II was
achieved in all cases except one TLab approach (p < 0.001).
Fourteen out of 21 patients were eligible for hearing preservation. A postoperative class A–B (Tokyo classification) was
obtained in 12 out of 14 patients (85.7%).
Premeatal meningiomas and especially the petroclival and
clival tumors are still considered the most challenging due to
their proximity to vital neurovascular structures. Until the
mid-1980s, these tumors were regarded as unresectable.
However, after pioneering efforts in skull base field, the surgical resectability started to increase. The several variations of
transtemporal approaches introduced in the 1990s allowed a
high resectability rate of premeatal tumors but surgical morbidity is still a major issue. In premeatal meningiomas, the
cranial nerves, notably the acoustic-facial bundle, are
displaced between the tumor and the surgeon and this is related with an increased rate of postoperative neuropathies.
Moreover, the transtemporal approaches have an intrinsic important morbidity causing deafness and, in particular, the TC
approaches, a partial facial nerve palsy grades II–III HB.
In the present analysis, for premeatal meningiomas, HB
grades I–II were obtained in 25/50 (50%) patients. More specifically, the rate of HB grades I–II was 80% (p < 0.001) for
Table 6 GTR according
to approach
GTR according to the approach
TLabTAp
TC
RS
POTS
TLab+FL
TLab
RLabST
Combined petrosal
18/20 (90%)
13/18 (72.2%)
9/9 (100%)
1/3 (33.3%)
0/1 (0%)
19/26 (73%)
2/2 (100%)
7/11 (63.6%)
TLabTAp approach, none for the TC approach, and in 9/11
(81.8%) out of combined petrosal approaches. For patients
who underwent the TC approach, the best VII C.N. function
we could achieve was an HB grade III in 15 out of 18 patients
(83.3%); in perimeatal and retromeatal meningiomas, HB
grades I–II were obtained in a high percentage (Table 8).
Hearing preservation was attempted only in 11 patients
with a very small premeatal meningioma, with the largest
diameter of maximum 2.5 cm. This goal was achieved managing the tumor by a combined petrosal approach.
Additionally, we reported 9/90 (10%) cases of IV, V, and VI
C.N. palsy, and 4/90 (4.4%) cases of lower cranial nerves
palsy (Table 7). In one case, we reported an ab-ingestis pneumonia and no cases of perioperative death, cerebrospinal fluid
leakage, or meningitis occurred.
Discussion
The objective of this study is to present surgical outcomes and
support an anatomic classification for PFM based on their
localization.
The extent of tumor resection has often been used as a
predictor of recurrence, as usually small pieces of tumor
may remain attached nearby. Prognostic factors for the recurrence of this tumor are well described in literature, such as the
growth rate. Interestingly, the reported growth rate is different
in untreated and resected tumors. As a matter of fact, Jung HW
et al. [8], have shown that the growth rate in petroclival meningiomas is 0.81 cm 3 /yr. (volume) and 0.81 mm/yr.
(diameter) after surgery as compared to 1.16 mm/yr.
(diameter) and 1.10 cm3/yr. (volume) for unresected tumors.
It is clear that a good resection is important, as the extent of
resection influences the rate of recurrence, which in turn influences the prognosis. However, deliberate residuals must be
Table 7
Postoperative morbidity
None
CN’s IX–X–XI–XII
CN’s IV–V–VI
CN VII
Trigeminal signs
Cerebellar signs
Retromeatal
Premeatal
Perimeatal
17/21 (80.9%)
3/21 (14.2%)
0/21 (0%)
1/21 (4.7%)
0/21 (0%)
0/21 (0%)
12/50 (24%)
1/50 (2%)
9/50 (18%)
25/50 (50%)
2/50 (4%)
1/50 (2%)
17/19 (89.4%)
0/19 (0%)
0/19 (0%)
2/19 (10.5%)
0/19 (0%)
0/19 (0%)
70
Table 8 Postoperative facial
nerve function
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HB in retromeatal
TLab
POTS
RLabST
RS
I–II HB
6/7 (85.7%)
3/3 (100%)
2/2 (100%)
9/9 (100%)
III HB
IV–V–VI HB
(p < 0.001)
1/7 (14.2%)
0/7 (0%)
0/2 (0%)
0/2 (0%)
0/2 (0%)
0/2 (0%)
0/9 (0%)
0/9 (0%)
HB in perimeatal
I–II HB
TLab
17/19 (89.4%)
III HB
IV–V–VI HB
(p < 0.001)
2/19 (10.5%)
0/19 (0%)
HB in premeatal
TLabTAp
TC
TLab+FL
Combined petrosal
I–II HB
16/20 (80%)
0/18 (0%)
0/1 (0%)
9/11 (81.8%)
III HB
(p < 0.001)
2/20 (10%)
15/18 (83.3%)
0/1 (0%)
0/11 (0%)
IV–V–VI HB
2/20 (10%)
3/18 (16.6%)
1/1 (100%)
2/11 (18.1%)
taken into account, as when the pia mater, jugular foramen,
cavernous sinus, and Gasser ganglion are infiltrated, pieces of
tumor are expressly left in situ.
Meningiomas in posterior fossa can grow and spread to
different locations [9•]. We easily divided them into three
groups according to their relation to IAC, as we observed that
they commonly can grow and develop nearby the IAC, with
progression towards the petrous apex or the CPA. Premeatal
tumors, which are located anterior to the IAC, exert mass
effect on the brain stem and trigeminal ganglion. They mainly
presented with symptoms attributable to involvement of the
fifth cranial nerve. As has been reported before [10•], cranial
nerve compression from meningioma can result in a spectrum
of facial numbness to trigeminal neuralgia. Perimeatal tumors
are more likely to present with hearing loss and vestibular
symptoms. This is coherent with prior papers that found normal hearing in only 20% of patients with tumors nearby these
regions [11]. Even though the facial nerve also crosses in this
Fig. 1 Rate of GTR, NTR, and
PTR
region, it was relatively skimped in all tumor groups, with no
patient presenting with facial weakness. Probably it can be
explained with a relatively earlier appearance of vestibular
symptoms (hearing loss, vertigo, and tinnitus) due to their
impact on daily activities. The facial nerve typically requires
more compression before facial motor deficits can be noticeable, the same finding in acoustic neuromas [11]. Retromeatal
tumors presented primarily with symptoms secondary to mass
effect or hydrocephalus rather than focal deficits, consistent
with others findings as headache, ataxia, and vertigo. Similar
findings are present in literature [12].
For years, skull base meningiomas have been considered
unresectable, but recent reviews have shown that they can be
operated upon with good outcome comparable to the convexity meningiomas [13]. Even though technical advancement of
surgery now permits total excision of many skull base lesions,
radical removal of meningiomas is not always possible.
Lesions of CPA and the surrounding skull base present a great
Curr Otorhinolaryngol Rep (2019) 7:65–72
challenge to the skull base surgeon in consideration of the
regional anatomy. Many surgical techniques have been developed for accessing these regions both for better exposure of
the site and to allow a low rate of morbidity by preserving
facial nerve function and hearing. Even if GTR remains the
gold standard for patients, the complete removal within the
restrictions of acceptable morbidity is not always achievable.
Few studies have looked at morbidity or mortality compared
across all approaches [14]. Our aim was to share our experience in the treatment of various diseases. The literature reports
that skull base meningiomas are believed to have a high rate of
recurrence and worse prognosis compared with intracranial
meningiomas, although the only statistically significant finding is that increasing age is associated with poor outcomes.
Surgeons’ experience has contributed to dispelling that belief.
GTR in our findings was the most common extent of resection
(Fig. 1).
We achieved a rate of GTR of 77% (p < 0.001) with
morbidity of about 89% for retromeatal and perimeatal
tumors. This is consistent despite of the most recent literature as many series demonstrated high GTR rate but
concomitant high morbidity rates [15]. Speaking of
which, common finding is that the retrosigmoid approach
is perhaps one of the most commonly used surgical approaches for removing skull base meningiomas [16].
However, in deciding which surgical approach fits better
to the patient, considerations must be given to tumor invasion of the cavernous sinus and IAC, to their tentorial
attachments, and to their forward expansion towards the
jugular foramen. Moreover, this approach leads to residual
tumor that is usually treated via conservative treatment,
such as radiotherapy. However, it should be emphasized
that CPA meningiomas with WHO grade II or higher
levels of morphological evidence have a higher risk of
recurrence in a relatively shorter period of time [17]. So
GTR is extremely important for these patients. Since radiosurgery does not guarantee the prevention of the recurrence of tumors, complete surgical resection is still the
main strategy to prevent tumor recurrence. The surgeon’s
choice of surgical approach depends mainly on the characteristics of the tumor and personal preferences. In our
centers, many different approaches were chosen based on
our understanding of the following: tumor origin, growth
direction, form and size, and the main symptoms related
to the invaded vital structures. Indeed, some other authors
suggest that the retrosigmoid approach has limitations,
such as a restricted angle of view, high venous pressures,
and suboptimal brain relaxation [18]. In comparison,
transpetrous approaches help to get a wide surgical field,
a shorter working distance between the craniectomy and
the tumor, and a better orientation towards the lateral and
ventral brain stem, limiting the brain retraction. Moreover,
it is possible to early identify and control the facial nerve
71
and to early resect the osteo-dural insertion of the meningioma, with coagulation of the tumor’s feeding vessels.
Our classification based on tumors’ location according to
the IAC helped us find out the best surgical approach in order
to achieve a GTR. Different surgical approaches and careful
microneurosurgical technique can be used to achieve improved surgical and functional outcomes. Resection is obviously related to surgical risk which often depends on tumor
site. Many related morbidities worry both patients and surgeons. According to literature, one concern is undoubtedly
facial nerve function, which is always taken into account in
almost all papers [9•]. Thanks to different surgical approaches,
HB grades I–II were achieved for the 69% of our patients.
Choosing a different approach for the three categories led us
to achieve a low rate of morbidity, particularly in retromeatal
and perimeatal groups. Ninety percent of patients in these
groups lacked complications. Premeatal tumors are the most
concerning due to their anatomical correlations with facial
nerve function affected in half of the patients. However, despite of the high surgical risks in treating these tumors, we
eventually achieved a 24% lack of complications in the
premeatal group. Last, hearing function, interestingly is not
as deeply considered as facial nerve function in the literature.
Transcochlear and translabyrinthine approaches require a sacrifice of hearing but often the decision to proceed with these
approaches is made because of large tumor extension involving the IAC, petrous ridge, clivus, or cavernous sinus, or because of brain-stem compression or basilar artery involvement. Moreover, as previously shown, these approaches let
us achieve a very high rate of GTR accounting about 73%
for TC and TLab approach themselves, which get stronger
the huge worth of these approaches.
Conclusions
Total resection is the only way to cure patients affected by
PCM. GTR is the aim of surgery as the extent of resection
influences the rate of recurrence, which in turn influences the
prognosis. We aimed to show how different surgical approaches may help to reach GTR and low morbidity, especially on facial nerve function. In this study, we reviewed a large
sample size of 90 patients with FCM. Though generally considered challenging to resect tumors at this location, different
approaches bore satisfactory results with an excellent extension of resection, preservation of cranial nerves, and low complication rates in our two centers.
Compliance with Ethical Standards
Conflict of Interest The authors declare that they have no conflicts of
interest.
72
Human and Animal Rights and Informed Consent This article does not
contain any studies with human or animal subjects performed by any of
the authors.
Curr Otorhinolaryngol Rep (2019) 7:65–72
10.•
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
Papers of particular interest, published recently, have been
highlighted as:
• Of importance
1.
Castellano F, Ruggiero G. Meningiomas of the posterior fossa. Acta
Radiol Suppl. 1953;104:1–177.
2. Martinez R, Vaquero J, Areitio E, Bravo G. Meningiomas of the
posterior fossa. Surg Neurol. 1983;19(3):237–43.
3. Thomas NW, King TT. Meningiomas of the cerebellopontine angle.
A report of 41 cases. Br J Neurosurg. 1996;10:59–68.
4. Mazzoni A. The petro-occipital trans-sigmoid approach for lesions
of the jugular foramen. Skull Base. 2009;19(1):48–56.
5. Ramachandra P, Tummala MD, Ernesto Coscarella MD, Jacques J,
Morcos MD. F.R.C.S. Transpetrosal approaches to the posterior
fossa. Neurosurg Focus. 2005;19(2):E6.
6. House JW, Brackmann DE. Facial nerve grading system.
Otolaryngol Head Neck Surg. 1985;93:146–7.
7. Simpson D. The recurrence of intracranial meningiomas after surgical treatment. J Neurol Neurosurg Psychiatry. 1957;20:22–39.
8. Jung HW, Yoo H, Paek SH, Choi KS. Long-term outcome and
growth rate of subtotally resected petroclival meningiomas: experience with 38 cases. Neurosurgery. 2000;46(3):567–74.
9.• Rogers L, et al. Meningiomas: knowledge base, treatment outcomes, and uncertainties: a RANO review. J Neurosurg.
2015;122(1):4–23. Response Assessment in Neuro-Oncology
(RANO) subcommittees are developing a paper on systemic
11.
12.
13.
14.
15.
16.
17.
18.
therapies for meningioma and a separate article proposing
standardized end point and response criteria for meningioma.
Magill ST, Rick JW, Chen WC, Haase DA, Raleigh DR, Aghi MK,
et al. Petrous face meningiomas: classification, clinical syndromes
and surgical outcomes. World Neurosurg. 2018. https://doi.org/10.
1016/j.wneu.2018.03.194. PFMs present with distinct clinical
syndromes based on their location along the petrous face:
anterior with trigeminal symptoms, middle with auditory/
vestibular symptoms, and posterior with symptoms of mass
effect/hydrocephalous. Surgical resection is associated with
excellent long-term survival and a low rate of recurrence,
which can be managed with radiotherapy.
Roser F, Nakamura M, Dormiani M, Matthies C, Vorkapic P, Samii
M. Meningiomas of the cerebellopontine angle with extension into
the internal auditory canal. J Neurosurg. 2005;102(1):17–23.
Velho V, Agarwal V, Mally R, Palande DA. Posterior fossa meningioma “our experience” in 64 cases. Asian J Neurosurg. 2012;7(3):
116–24.
Anil Nanda and Prasad Vannemreddy. Recurrence and outcome in
skull base meningiomas: do they differ from other intracranial meningiomas? SKULL BASE/VOLUME 18, NUMBER 42008.
Michael L. DiLuna and Ketan R. Bulsara. Surgery for petroclival
meningiomas: a comprehensive review of outcomes in the skull
base surgery era. SKULL BASE/VOLUME 20, NUMBER 52010.
Joseph P. Roche et al., Treatment of lateral skull base and posterior
cranial fossa lesions utilizing the extended middle cranial fossa
approach. Otology. Neurology. 2017;38(5).
He X, Liu W, Wang Y, et al. Surgical management and outcome
experience of 53 cerebellopontine angle meningiomas. Cureus.
2017;9(8):e1538. https://doi.org/10.7759/cureus.1538.
Couldwell WT, Cole CD, Al-Mefty O. Patterns of skull base meningioma progression after failed radiosurgery. J Neurosurg.
2007;106(1):30–5.
Sanai N, McDermott MW. A modified far-lateral approach for large
or giant meningiomas of the posterior fossa. J Neurosurg. 2010;112:
907–12.