© Springer International Publishing AG 2018 145
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_11
Vestibular Schwannomas
Gmaan Alzhrani, Clough Shelton,
and William T. Couldwell
G. Alzhrani, MD • W.T. Couldwell, MD, PhD (*)
Department of Neurosurgery, Clinical Neurosciences
Center, University of Utah, 175 N. Medical Drive
East, Salt Lake City, UT 84132, USA
e-mail: [email protected]
C. Shelton, MD
Division of Otolaryngology – Head and Neck
Surgery, University of Utah School of Medicine,
Salt Lake City, UT, USA
11
Introduction
Vestibular schwannomas (VSs) are benign nerve
sheath tumors originating along the vestibuloco-
chlear nerve course that account for 6–8% of all
intracranial tumors. VS is the most common
pathology found in the cerebellopontine angle
(CPA), accounting for up to 80% of tumors there
[ 19 ]. The management options of these tumors
are observation, radiation therapy, and surgical
removal, depending on imaging findings and
clinical presentation. The surgical removal of
VSs is accomplished through three main surgical
routes: the middle fossa approach (MFA), the
translabyrinthine approach, and the retrosigmoid
approach.
The choice of microsurgical approach for VS
tumors is multifactorial and depends on the
tumor size, patient age, tumor site and extent of
internal auditory canal (IAC) involvement, anat-
omy of the vestibule, amount of tumor extension
in the CPA, brainstem involvement, preoperative
hearing status, and surgeon’s preference [ 1 , 16 ,
26 , 34 ].
The availability of superior microscopes,
safer high-speed drills, better hemostatic agents,
and intraoperative neuromonitoring has led to
an evolution in the goals of microsurgery for
VS, which have progressed from preserving life
to preserving facial nerve function and now to
hearing preservation [ 8 , 11 , 20 ]. Whereas the
translabyrinthine approach sacrifices hearing to
achieve greater exposure, the MFA and retrosig-
moid approaches to resection of VS tumors
offer the possibility of hearing preservation. In
this chapter, we describe these three most com-
monly used approaches for the removal of VSs
and their technical nuances.Retrosigmoid Approach
IndicationsThe retrosigmoid approach is indicated in patients
undergoing removal of VS of any size or when an
attempt at hearing preservation is to be made with
smaller tumors, either intercanalicular or extra-
canalicular. From a practical standpoint, the retro-
sigmoid approach is used by the senior authors for
large tumors, as it offers expansive view of the
posterior fossa for rapid verification of neurovas-
cular anatomy, and for medial acoustic tumors in
which hearing preservation is the goal of surgery.