© Springer International Publishing AG 2018 103
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_8
Meningiomas
of the Cerebellopontine Angle
Stephen T. Magill, Philip V. Theodosopoulos,
Aaron D. Tward, Steven W. Cheung,
and Michael W. McDermott
S.T. Magill, MD, PhD (*) • P.V. Theodosopoulos, MD
M.W. McDermott, MD
Department of Neurological Surgery, University of
California, San Francisco, CA, USA
e-mail: [email protected];
[email protected];
[email protected]
A.D. Tward, MD, PhD • S.W. Cheung, MD
Department of Otolaryngology, University of
California, San Francisco, San Francisco, CA, USA
e-mail: [email protected]; [email protected]
8
Anatomic Classification
The posterior face of the petrous temporal bone
forms the lateral boundary of the CPA, while the
pons and cerebellum form the medial boundary,
the tentorium the superior boundary, and the
jugular foramen the inferior boundary. Along the
medial anterior aspect of the petrous bone runs
the petro-occipital suture, which defines petro-
clival meningiomas when more than 25% of
their attachment lies medial to this suture.
Lateral to this and anterior to the internal audi-
tory canal (IAC) is what can be referred to as the
“anterior petrous face” meningiomas (APFM)
(Fig. 8.1a, d). These tumors tend to present clini-
cally with trigeminal symptoms such as numb-
ness or pain (trigeminal neuralgia). Their arterial
supply comes from non-internal carotid artery
and non- tentorial artery dural feeders [ 10 ].
Tumors of the middle petrous face straddle
the IAC and usually have a point of origin
above the internal acoustic meatus and can be
referred to as “middle petrous face” meningio-
mas (MPFM) (Fig. 8.1b, e). These are the
tumors that Cushing referred to as “those simu-
lating acoustic tumors,” as they present with
audiovestibular symptoms such as tinnitus,
hearing loss, dizziness, and vertigo [ 9 ]. The
hearing loss tends to manifest as decreased
pure tone audiometry and impaired speech
audiometry. Interestingly, high-frequency hear-
ing is preserved, in contrast to the high-
frequency sensorineural hearing loss that
occurs with vestibular schwannoma [ 2 ].
Tumors arising from the region from the IAC
posteriorly to the sigmoid sinus can be referred to
as “posterior petrous face” meningiomas (PPFM)
(Fig. 8.1c, f). In the lower 1/3 of the petrous face
lies the vestibular aperture, an oblique opening in
the bone for the vestibular aqueduct. The vestibu-
lar aqueduct terminates in a blind sac called the
endolymphatic sac that lies partially embedded in
folds of posterior petrous face dura. Even small
tumors overlying the endolymphatic sac have
been associated with audiovestibular symptoms
resembling Meniere’s syndrome. It is likely that
compromise of the as yet poorly understood func-
tion of the endolymphatic sac gives rise to altera-
tions in the fluid spaces of the inner ear, thus
potentially giving rise to cochlear and vestibular
dysfunction [ 8 ]. Large tumors of the posterior