Skull Base Surgery of the Posterior Fossa

© Springer International Publishing AG 2018 115
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_9

Tentorial Meningiomas

Hiroki Morisako, Takeo Goto, and Kenji Ohata

Introduction

The surgical treatment of tentorial meningiomas has
been a challenge for most neurosurgeons over the
years [ 1 , 2 ]. Tentorial meningiomas are estimated to
represent only 2–4% of all intracranial meningiomas
[ 1 ]. Because of the intricate anatomical relationship
of the tentorium to the surrounding neurovascular
structures, their location and extension need to be
precisely delineated before surgery [ 1 ].
The morphological features of the downward
sloping of the tentorium from its apex anteriorly
to the petrous bones laterally add a complicating
factor when accessing these meningiomas. More
recent advances in microsurgical techniques and
skull base approaches have made access and
resection of some of these larger and medially
located tumors less difficult.
Tentorial meningiomas can be divided into
incisural, falcotentorial, lateral, and posterior
types according to their sites at the tentorium cer-
ebelli (Fig. 9.1). In this chapter, the features of
each type of tentorial meningioma are explained,
with a focus on the surgical perspective.

Incisural Type

Surgical excision of meningiomas involving the

tentorial incisura is a significant technical chal-

lenge, mainly due to access, especially for medi-

ally located lesions, as well as their relationship

to the brain stem, cranial nerves, temporal lobe,

blood vessels, and venous sinuses.

Meningiomas arising from the tentorial incisura

grow up around the interpeduncular, crural, and

ambient cisterns. Since they sometimes encase

cranial nerves and blood vessels, such as the supe-

rior cerebellar artery or trochlear nerve, resection

of the tumor requires great care to avoid any

neurological dysfunction. If the tumor is huge, the

tumor compresses the brain stem and adheres to it,

thus making total resection relatively difficult.

Surgical Planning

Preoperative brain MRI scans and preoperative

vascular studies (MRA, CTA, or angiogram)

should be evaluated to identify the location of

tumor extension, as well as the relationship to the

brain stem, any encasement of vessels, and involve-

ment of the cavernous sinus. In the case of incisura

type, the venous system is crucial for planning sur-

gery. Evaluation of the transverse and sigmoid

sinuses and their connection at the torcular

Herophili is important for lateral and posterior

approaches. The venous drainage pattern of the

H. Morisako, MD, PhD • T. Goto, MD, PhD
K. Ohata, MD, PhD (*)
Department of Neurosurgery, Osaka City University
Graduate School of Medicine, 1-4-3 Asahi-machi,
Abeno-ku, Osaka 545-8585 Osaka, Japan
e-mail: [email protected];
[email protected]; [email protected]

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