1. Meningiomas of the Middle
Fossa Floor
Present By : Ayu Iswandari Raharjo
Neurosurgery Departement
Fakultas Kedokteran Universitas
Padjajaran
2022
2. INTRODUCTION
A large fraction of these meningiomas arise from the
dural surfaces bordering the middle fossa, namely
Middle Cranial Fossa
is a common location of
meningiomas of the cranial base
The
cavernous
sinus
Sphenoid
wing
Tentorium Convexity
and extend into the middle fossa, filling the
concavity of the middle fossa floor secondarily.
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3. INTRODUCTION
Meningiomas can, however, arise directly from the floor of the middle
fossa, with minimal or no connection to the aforementioned border sites
These tumors have been less well studied, in large part due to a lack of
a firm radiographic definition of “middle fossa” meningioma
These tumors likely have been previously classified as sphenoid wing,
cavernous sinus, or other meningiomas
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4. As a histologically confirmed meningioma with greater than 75% of its radiographic
attachment on the floor of the middle fossa, with less than 25% attachment on either
DEFINITION
Middle Fossa Floor Meningioma
sphenoid wing
cavernous
sinus
petrous
ridge/tentorium
lateral
convexity dura
which form the four anatomical boundaries of the middle fossa
concavity as determined by magnetic resonance imaging (MRI)
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5. DEFINITION
Schematic diagram demonstrating anatomical definition
of middle fossa meningiomas. The numbers 1–5 depict
the classification scheme for these tumors.
Subclassification :
radiographically had no attachments to boundaries of
the middle fossa (class 1)
those that had between 0 and 25% attachment to the
sphenoid wing (class 2)
cavernous sinus (class 3)
dura over the petrous ridge and tentorium (class 4)
convexity dura (class 5)
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6. DEFINITION
Definition of Different Classes of
Middle Fossa Floor Meningiomas
it is possible in this definition for a tumor to
be a middle fossa floor meningioma and
still have some cavernous sinus invasion if
the principal site of origin is the middle
fossa floor.
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8. INCIDENCE
Study from University of California–San Francisco
(UCSF) between 1991 and 2006, 1213 patients were
registered as meningioma patients and of which 1034
patients underwent treatment of their lesion with
either open surgery or radiosurgery.
A total of 17 patients in this series met criteria for
having a middle fossa floor meningioma.
Exact incidence of middle fossa floor meningiomas is not known
This book estimate that these lesions represent 1.4%
of all known or presumed intracranial meningiomas
and 6% of all meningiomas in the middle fossa
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9. CLINICAL PRESENTATION
● These tumors are often rather large at diagnosis and can present with a wide variety of
nonspecific or confusing symptoms
● The median patient age at time of surgery : 57 yo
● Male to female ratio 6:9
● The median volume of these tumors was 21 cc with maximum volume ever reported > 70cc, with
a maximum tumor diameter of 5.5 cm
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10. CLINICAL PRESENTATION
Headache (the most
common complaint
60%)
Seizures (40%)
Trigeminal nerve
dysfunction
(numbness, palsy,
or neuralgia present
in 33%)
Gait disturbance
Cognitive decline Hearing loss
Presenting Symptoms and Preoperative Neurological Deficits
of the 15 Patients in This Series
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11. Anatomical Tumor Considerations
In the author case series :
eight patients
had class 1
tumors
Two patients
had class 2
tumors
three patients
had a minor
degree of
cavernous
sinus invasion
(class 3)
four patients
had minor
tentorial
attachment
(class 4).
meaning that
they arose
solely from the
floor of the
middle cranial
fossa.
meaning they
had a minor
attachment to
the sphenoid
wing
Ten patients underwent
preoperative endovascular
embolization
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12. OPERATIVE TECHNIQUE
Lumbar CSF drainage is usually
not necessary when an adequate
craniectomy of the squamous
temporal bone brings the
approach angle flush with the
middle fossa floor
Suggestions for the surgical
approach based on the middle
fossa meningioma
classifications
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13. OPERATIVE TECHNIQUE
In some cases where the superior pole of the tumor was quite high (> 5 cm from the
middle fossa floor) a limited inferior and middle temporal gyrus corticectomy is used to
facilitate efficient removal and avoid extensive retraction of the lateral temporal lobe.
When possible, the base of the tumor is first detached from middle fossa floor
attachments, devascularizing the tumor in the process. Internal debulking was then
performed, followed by peripheral dissection.
Care should be taken to avoid more than 60 degrees of head rotation to avoid restriction
of venous outflow.
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15. SURGICAL OUTCOME
Median length of stay for these patients was 6 days (range 3 to 15 days).
Authors were able to achieve a simpson grade i or ii resection in 10/15 patients
(67%).
Four out of 15 patients (26%) had tumors demonstrating world health
organization (who) grade ii histology.
Two of these patients had subtotal (simpson grade iv) resections due to firm
adherence to cranial nerves or cavernous sinus invasion.
Three of five patients with a simpson grade iii or iv resection had tumors that
involved the cavernous sinus.
Four of these five patients underwent subsequent radiotherapy
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16. SURGICAL OUTCOME
Despite the general lack of proximity to cranial nerves, these tumors should be viewed with relative
caution because the rate of at least one complication in the author’s experience was 33%
This may be due to the rather large size these tumors reach before
diagnosis.
There was no early postoperative mortality in these patients
The operative morbidity in this series was clustered in five patients (on
the table below)
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17. SURGICAL OUTCOME
Abbreviations: GTR, gross total resection; STR,
subtotal resection; WHO, World Health Organization.
Clinical Outcome for the 15 Patients
in This Series
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18. SURGICAL OUTCOME
After followed up :
these patients have a median of 5 years (range 1 to 15 years).
There have been a total of four known clinical recurrences in this group.
Three reccurrences were treated with stereotactic radiosurgery, and one patient with a WHO
grade II tumor received repeat surgery and external beam radiotherapy.
all of the patients with recurrence had either higher-grade tumors (two patients), or had a
Simpson grade III or higher resection
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20. CONCLUSION
Meningiomas of the middle fossa
floor are a recently recognized entity
for which the natural history and
outcomes are as yet not well
understood
The author propose
that Meningiomas of
the middle fossa can
be classified by their
degree of tumor
attachment to the
middle fossa floor and
surrounding dura.
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21. CONCLUSION
It would be a mistake for a surgeon to mentally classify a tumor as a “sphenoid wing” meningioma,
when it is truly a class 2 middle fossa meningioma, and to approach the case with the plan of
primarily addressing the attachments of the tumor at the sphenoid wing, when greater than 50% of
the tumor attachment lies on the floor of the middle fossa
the morbidity of resecting these tumors is not trivial, with one third of patients
suffering at least one notable postoperative complication
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