97Complications and Their Avoidance
Morbidity arising from this approach includes
hearing loss, facial weakness, decreased tearing,
CSF leak, and temporal lobe injury leading to
seizures and dysphasia. The bony labyrinth sur-
rounding the SCC and the cochlea can be identi-
fied by their distinct color and thickness of the
bone, which facilitates avoiding these structures.
The petrous segment of the ICA is also at risk of
exposure and damage along the anterolateral
aspect of Kawase’s triangle. The GSPN is an
accurate landmark for the underlying petrous
ICA, and careful attention to its course can help
prevent ICA injury. The use of neuronavigation
can further reduce the risk of iatrogenic injury to
bony and vascular structures. To prevent
decreased tearing and to maintain the integrity of
the GSPN, it is dissected off the periosteum
invested over it in a posterior to anterior direction
to prevent traction avulsion of the nerve from the
geniculate ganglion and also indirect facial pare-
sis that may ensue. CSF leaks can be avoided by
meticulous waxing of exposed air cells. Use of
appropriate autologous grafts (fat/pericranium/
muscle) or dural substitutes ensures optimal
reconstruction of the dural defect along the skull
base. SPS ligation distal to the drainage of the
vein of Labbé can lead to disastrous sequelae,
especially in the dominant lobes. To understand
the venous drainage pattern, careful assessment
of the preoperative CT/MR venogram is essen-
tial. The use of lumbar drainage and intermittent
use of retraction can help prevent this
complication.
Posterior Transpetrosal Approach
Indications and Limitations
The ideal candidates for posterior transpetrosal
approach are patients with large PC tumors with
their epicenter in the infratentorial compartment,
extending across the midline as well as lateral to
the IAC and inferiorly along the lower third of the
clivus. Depending on the preoperative hearing sta-
tus of the patient and the extent of the ventral brain-
stem exposure required, there is a choice of various
modifications of the posterior transpetrosal
approach: retrolabyrinthine, transcrusal, translaby-
rinthine, and transcochlear approaches [ 21 ]. The
advantages of these approaches include direct,
short, and wide access to the PC region with ade-
quate surgical freedom to access tumors extending
across midline along ventral brainstem and lateral
to IAC. These approaches demonstrate beautifully
the principle of removing bone to avoid retracting
the brain for visualization. Tumor vascularity is
reduced by the approach, as all vascular supply
emanating through the bone is removed with the
approach. They are limited by the ability to visual-
ize and resect the supratentorial component of the
tumor, which may warrant a combined approach
with anterior transpetrosal approach. Given the fact
that these are essentially presigmoid approaches,
dominance of the ipsilateral sigmoid sinus may
limit the surgical view and easy maneuverability.
Therefore, careful assessment of venous drainage
patterns and anatomy is pivotal to ascertain the
safety and feasibility of these approaches [ 13 ].Surgical Technique and Nuances
The senior author prefers to perform these proce-
dures with the patient in the lateral approach.
This reduces neck rotation, and ventilation of the
patient is unimpeded. Apart from the usual
patient preparation, the abdomen is also prepared
to harvest autologous fat graft. The incision is
typically a C-shaped or curvilinear incision in the
retroauricular region intended to expose the infe-
rior aspect of the temporal bone, the mastoid pro-
cess, and the suboccipital region. Next, the
mastoidectomy is performed until the mastoid
antrum—which lies posterior to the posterior ear
canal and acts as an internal landmark for the
vital middle ear structures—is opened. The mas-
toid antrum is also situated deep within the
Macewen’s triangle and posterior to the spine of
Henle. Further drilling can be done using neuro-
navigation assistance or with the help of an oto-
rhinolaryngologist to expose the sigmoid sinus
and deeper otic capsule. The posterior semicircu-
lar canal can be identified deep to the mastoid
antrum, and the fallopian bony canal of the facial
nerve can be identified by a short process of incus
and also by its location at the anterior and inferior
border of the antrum [ 21 ]. Depending on the7 Petroclival Meningiomas