Phẫu Thuật Tai Mũi Họng Và Phẫu Thuật Đầu Cổ

988
Section 11
Cranial Base Surgery
The frontal lobe dura is then carefully elevated
from the roof of the orbits and the crista galli and crib-
riform plates. Because of perforations of the olfactory
nerves, multiple dural lacerations in the region of the
cribriform plate necessarily result. It may be necessary
to incise the dura along the crista galli. If there is intra-
cranial extension of tumor with potential involvement
of dura, a patch of dura is incised and left attached to
the tumor specimen. In rare instances it may be neces-
sary to resect a portion of one or both frontal lobes to
obtain an adequate tumor margin. To maximize addi-
tional exposure while minimizing frontal lobe retrac-
tion, the supraorbital rims and nasion are removed as
a single bone segment (Fig. 100-20). While the brain
and orbit are protected by malleable retractors, a recip-
rocating saw with a long blade is used for osteotomies
through the orbital rims at approximately the supraor-
bital notch. The cuts are beveled laterally to allow
greater stability of the bone segment at the time of
closure. Osteotomies through the orbital roof are made
with reciprocating or oscillating blades (Fig. 100-21).
An attempt is made to remove a large portion of the
orbital roof as a single unit to avoid postoperative prob-
lems with enophthalmos because of loss of the orbital
walls or pulsating exophthalmos because of contact of
the brain with the soft tissues of the orbit. Near the
midline, the osteotomy is necessarily directed to the
anterior margin of the cribriform plate. A horizontal
osteotomy is then made through the nasion superior to
the level of the frontoethmoid suture line. The tip of
the saw blade is placed approximately 2 cm deep to the
nasion for this cut. This osteotomy usually transgresses
the nasofrontal ducts superior to the ethmoid labyrinth.
The entire bone segment, including both orbital rims
and orbital roofs, can then be further mobilized, if
necessary, with an osteotome.
Additional elevation of frontal lobe dura can then
be performed with minimal brain retraction. After iden-
Figure 100-18. Various segments of the frontal bone and supraor-
bital rims may be removed to provide adequate exposure of the
anterior cranial base.
Figure 100-19. This patient required a bifrontal and left temporal
craniotomy. The left orbital rim and zygomatic arch were removed as
a single unit to provide additional subfrontal and anterolateral
exposure.
A
B
Figure 100-20. A, The superior orbital rims and nasion may be
removed as a single bone unit to provide additional subfrontal expo-
sure. B, This provides additional access to the limits of the anterior
cranial base (arc A) with decreased need for frontal lobe retraction
(arc B).

Chapter 100
Surgery of the Anterior Cranial Base
989
tifi cation of the planum sphenoidale posterior to the
crista galli and cribriform plates, the anterior clinoid
processes and optic canals are identifi ed bilaterally. In
patients with tumor in proximity to the orbital apex, the
optic canal is carefully decompressed with Kerrison ron-
geurs. Decompression is performed to prevent an
entrapment syndrome postoperatively as a result of
edema of the optic nerves. An opening is next made
through the planum sphenoidale into the sphenoid
sinus with cutting burrs. The sinus may then be
inspected for evidence of tumor involvement. Bone
removal from the roof of the sphenoid sinus continues
anterolaterally on both sides toward the orbit (Fig. 100-
22). If tumor does not involve the ethmoid sinus, the
bone cut extends through the ethmoid air cells. When
there is involvement of the sinus, the medial orbital wall
is included to provide an adequate resection margin
(Fig. 100-23).
Extracranial exposure of the neoplasm is now
obtained with a lateral rhinotomy or midfacial deglov-
ing approach or with an endoscopic-assisted approach
(see Chapter 10). Resection of the medial orbital wall
is facilitated with this approach. The intracranial expo-
sure allows en bloc removal of the anterior cranial base
with direct visualization of the optic nerves and the
lateral walls of the sphenoid sinus with the internal
carotid artery. An osteotome, drill, or Mayo scissors may
be used to transgress the anterior wall of the sphenoid
sinus, thus separating the specimen from its attachment
inferiorly. Transection of the nasal septum from below
is necessary to mobilize the specimen. This cut extends
from the nasion anteriorly and superiorly to the poste-
rior edge of the nasal septum inferior to the rostrum of
the sphenoid.
After removal of the specimen, the defect is exam-
ined and additional bone or soft tissue margins can be
obtained under direct visualization from above. A large
defect frequently results in direct communication
between the cranial cavity and the nasopharynx (Fig.
100-24).
Open Reconstruction
Every attempt should be made to attain a watertight
closure of the dura to minimize the risk of a postopera-
Figure 100-21. The sphenoid sinus is opened in the region of the
planum sphenoidale. Osteotomies are then made anteriorly and lat-
erally through the roof of the orbit or fovea ethmoidalis. Anteriorly,
an osteotomy is made anterior to the crista galli.
A
B
Figure 100-22. Depending on the extent of the tumor, the medial
wall of the orbit may be included with the ethmoid sinus to provide
an adequate tumor margin.
Figure 100-23. A, In this patient with a malignant neoplasm of the
nasal cavity, it was necessary to remove only a short segment of the
nasion (curved arrows). B, After removal of this bone segment, addi-
tional osteotomies were made through the fovea ethmoidalis bilater-
ally and across the roof of the sphenoid sinus posteriorly (arrows).

990
Section 11
Cranial Base Surgery
tive CSF leak and resultant meningitis. Small lacerations
of the dura may be closed primarily. Larger defects of
the dura may require the use of a fascial graft. Suitable
materials include fascia lata harvested from the lateral
aspect of the thigh or cadaveric dura. It is not necessary
to remove all the mucosa from the sphenoid sinus
unless a pericranial fl ap is used to obliterate the sinus.
Defects of the anterior skull base, including the
cribriform plate, planum sphenoidale, and roof of the
sphenoid sinus, can be reconstructed with a vascular-
ized pericranial scalp fl ap. The fl ap is designed as an
inverted U based on the supraorbital neurovascular
bundles (Fig. 100-25). The primary blood supply of the
fl ap comes from the supraorbital and supratrochlear
vessels, although the anterior branches of the superfi -
cial temporal artery can also be included. The pericra-
nial layer is easily dissected from the galea, beginning
at the edge of the bicoronal scalp fl ap. The layer is ele-
vated with tenotomy scissors down to the level of the
supraorbital rim (Fig. 100-26). It is important to dissect
close to the undersurface of the galea to maximize the
thickness of the pericranial fl ap. As one approaches the
base of the fl ap, it becomes more diffi cult to separate
the galeal and pericranial layers, and extra care is
needed to avoid injury to the vessels at this point. If
necessary, the arc of rotation of the fl ap can be increased
by incising its base on one side. A unilateral blood
supply has proved to be adequate for survival of the
fl ap.
The pericranial fl ap may be transferred into the
defect above or below the supraorbital bone graft. The
latter is preferred to increase the reach of the fl ap and
to separate the supraorbital bone graft from the nasal
cavity. The distal edge of the pericranial fl ap is sutured
to the dura at the posterior limit of the cranial base
defect (Fig. 100-27). In elderly patients with thin dura,
this may be quite diffi cult because of tearing of the
dura. In such cases it may be necessary to place small
drill holes at the posterior margin of the defect for
suturing of the pericranial fl ap. Laterally, the pericra-
nial fl ap is sutured to the periorbita.
A galeal-pericranial fl ap is preferred for larger
defects or when the vascularity or integrity of the peri-
cranium is in question. The fl ap requires dissection of
Scalp
Scalp
Orbit
Orbit
Dura/Brain
Dura/Brain
Orbit
Orbit
Scalp
Orbit
Dura/Brain
Orbit
Figure 100-24. After resection of the neoplasm, a large defect of
the anterior cranial base remains and communicates with the para-
nasal sinuses.
StA
SoA
STA
Figure 100-25. An anteriorly based pericranial fl ap receives its
blood supply from the supratrochlear (StA) and supraorbital (SoA)
vessels. The superfi cial temporal artery (STA) also contributes to the
vascular supply of the galeal layer.
Pericranium
Figure 100-26. The pericranial fl ap is dissected from the galea by
sharp dissection to the level of the orbital rim.

Chapter 100
Surgery of the Anterior Cranial Base
991
the galeal-pericranial layer from the skin at a plane
between the frontalis muscle and the hair follicles. The
thickness and vascularity of this fl ap are superior to that
of the pericranial fl ap, but at the expense of the vascu-
larity and thickness of the bicoronal scalp fl ap. In cases
in which the pericranium is not available, the galea may
still be used as a fl ap. Rarely, the galeal and pericranial
fl aps may be used separately to cover different defects.
The use of free bone grafts in conjunction with
these fl aps does not appear to contribute to support of
the brain and is associated with a higher incidence of
infection and osteoradionecrosis. The use of nonvascu-
larized tissue is avoided as much as possible to decrease
the risk of wound infection. Placement of a nonvascu-
larized fat or bone graft against a nonvascularized dural
graft may interfere with vascularization of the dura. The
pericranial fl aps are rapidly mucosalized on the nasal
surface. Therefore, skin grafting is not recommended.
(For anterolateral defects, see Chapter 101.)
Before replacement of the bone fl aps, it is neces-
sary to remove all mucosal remnants from the frontal
sinus to prevent postoperative mucocele formation.
The frontal sinus is cranialized by removing the poste-
rior table of the frontal sinus with rongeurs or a saw.
The mucosa is then stripped from the sinus with an
elevator. Removal of mucosal remnants in deep crevices
is facilitated by the use of a cutting burr. The mucosa
is also stripped from the nasofrontal ducts, and the
ducts are obliterated with Surgicel or soft tissue plugs.
The craniotomy and supraorbital bones are then
replaced superior to the pericranial fl ap. Care is taken
to avoid compression of the vascular supply of the fl ap
by the bone. It may be necessary to remove an addi-
tional 2 to 3 mm of bone in the midline to prevent
compression. The bones are held in place with multiple
2-0 braided nylon sutures through drill holes in the
margins of the bone or with microplates. Titanium
microplates are currently preferred because of greater
stability of the bone fl ap, rapid repair, and the ability
to cover small bone defects. This affords adequate sta-
bilization of the bones with excellent healing and bony
union. Steel wire and nontitanium plates are not gener-
ally used because of the potential for scatter artifacts on
postoperative radiologic imaging. Bone dust and chips
are used to fi ll defects surrounding the craniotomy
bone fl ap. Titanium burr hole covers may also be used
to cover burr holes when adequate autologous bone is
not available (Fig. 100-28). Alternatively, the inner
cortex of the bone fl ap or the posterior wall of the
frontal sinus may be used for bone reconstruction.
Larger defects may be covered with titanium mesh.
A Jackson-Pratt drain is use for drainage of the
wound. The exit wound is placed posterior to the inci-
sion line to avoid potential compromise of the vascular
supply to the anterior portion of the scalp. Whenever
there is the potential for a CSF leak, the drain is placed
to empty by gravity with the use of a bile bag. There are
potential risks of excessive CSF drainage or sudden
cardiac arrest as a result of changes in intracranial pres-
sure if high suction is applied to the drains. The ante-
rior margins of the temporalis muscle are then sutured
to the cranium to prevent a cosmetic defect, and the
scalp incision is closed with interrupted 2-0 Vicryl or
Dexon sutures. Staples are used for skin closure. Telfa
coated with povidone-iodine ointment is applied to the
suture line, and a standard neurosurgical gauze com-
pressive dressing is applied. It is important to make sure
that there are no compressive points anteriorly that
might compromise anterior scalp vascularity.
Endoscopic Technique
We have described several endoscopic “modules” based
on exposure and control of key anatomic structures.
Although this chapter addresses resection of the ante-
rior skull base for the specifi c indication of sinonasal
tract malignancies, we consider this approach to be part
of an encompassing modular system that provides endo-
Pericranium
Pericranium
Pericranium
Figure 100-27. The pericranial fl ap is rotated posteriorly and
sutured to bone, mucosa, or dura at the posterior margin of the surgi-
cal defect. Laterally, the pericranial fl ap is sutured to the orbital
tissues to provide watertight separation of the nasopharynx from the
cranial cavity. This step is performed before replacement of the supra-
orbital and craniotomy bone fl aps.
Figure 100-28. Bone defects may be covered with titanium burr
hole covers to prevent a postoperative deformity.

992
Section 11
Cranial Base Surgery
scopic exposure of the entire anatomy of the sinonasal
tract and the anterior and middle skull base and clival
region.13-18
Patients are positioned supine on the operating
table with the head in neutral position and fi xed by a
three-pin head holder with the neck slightly rotated to
the right side. If exposure of the frontal sinus (endo-
scopic Lothrop or Draf III procedure) will be required,
the head is extended mildly. Video monitors are posi-
tioned directly in front of the surgeons.
The nasal cavity is decongested with cottonoids
soaked in 0.05% oxymetazoline and then examined
with 0- and 45-degree endoscopes. One percent lido-
caine with 1 : 100,000 epinephrine may be infi ltrated
into the lateral nasal wall, middle turbinates, posterior
nasal septum, and rostrum of the sphenoid sinus for
additional hemostasis. Infi ltration must be avoided in
areas involving the vascular pedicle for a nasoseptal fl ap
if one is to be harvested. The operation begins with
debulking of the tumor or with exenteration of the
anterior paranasal sinuses, depending on the origin,
extent, position, and bulk of the tumor. The tumor is
debulked with a microdébrider to increase exposure of
the skull base. Dissection of the paranasal sinuses follows
a technique similar to that used for the management of
infl ammatory disease. The dissection can be unilateral
or bilateral, depending on the extent of the tumor.
Uncinectomy is followed by identifi cation and widening
of the natural ostium of the maxillary sinus in a poste-
rior and inferior direction. A wide middle meatal
antrostomy helps defi ne the inferior and medial walls
of the orbits and exposes the posterior wall of the
antrum, thereby facilitating control of the sphenopala-
tine and posterior nasal arteries. Completion of ante-
rior and posterior ethmoidectomies and exposure of
the nasofrontal recess will defi ne and expose the para-
median anterior skull base, including the fovea eth-
moidalis, the vertical and horizontal lamellae of the
cribriform plate and its olfactory fi la, and the anterior
and posterior ethmoidal artery canals. The middle tur-
binates may also be removed to create more room for
intranasal instrumentation.
At this point, if a vascularized nasoseptal fl ap is
required for reconstruction and the oncologic princi-
ples of resection can be respected, it is harvested from
the nasal septum. Until recently, options for endoscopic
reconstruction of the skull base were limited to the use
of nonvascularized tissue. This resulted in CSF leak
rates of 20% to 30% and became a major obstacle to
widespread acceptance of these techniques. Recently,
the Haddad-Bassagasteguy fl ap (HBF), or nasoseptal
fl ap, has proved to be a versatile, robust vascularized
fl ap for the reconstruction of expanded endonasal
approaches defects.19 Since adopting this technique,
our CSF leak rates have dropped to numbers that
compare with those of traditional techniques (around
5%). The advantage of this fl ap as a reconstructive
option is that a second approach or incision is not nec-
essary and the fl ap can be harvested endoscopically.
The major drawback of the HBF is that its need must
be anticipated before embarking on resection because
the vascular pedicle to this fl ap is frequently compro-
mised during the sphenoidotomy and posterior septec-
tomy portion of the procedure. In addition, if a revision
procedure is necessary, the fl ap may have been used
previously or the pedicle previously damaged.
Design of the fl ap should be based on the expected
size of the defect. This point is counterintuitive to most
reconstructive surgeons because the fl ap is harvested
before the resultant defect is created; thus, one can be
left with a fl ap that is inadequate. As a result of this
potential fl aw, we tend to harvest a larger fl ap. The fi rst
incision is the most critical and involves the use of elec-
trocautery along the free edge of the choana from the
lateral nasal wall toward the nasal septum. This incision
is exceedingly diffi cult to perform once the fl ap has
been elevated, so extra time and patience are warranted
to ensure a full incision down to the level of the sphe-
noid fl oor. Two longitudinal incisions are then created
in a posterior-to-anterior direction. The most inferior
incision is placed along the maxillary crest; however, it
can be extended inferiorly and laterally to harvest the
mucoperiosteum of the nasal fl oor. The superior inci-
sion is created 1.0 to 1.5 cm inferior to the cribriform
plate to preserve olfactory function. It then crosses the
rostrum of the sphenoid at the level of the sphenoid
sinus os. This leaves approximately a 1- to 2-cm width
of pedicle across the anterior face of the sphenoid.
Both these incisions are joined anteriorly with a vertical
incision at the level of the anterior end of the inferior
turbinate. Once all the incisions are completed, the fl ap
is elevated in a subperichondrial and subperiosteal
plane back to its pedicle on the sphenopalatine foramen.
The fl ap can then be “stored” for the duration of the
resection in the nasopharynx or inside the antrum
through a wide maxillary antrostomy.
In the event that a fl ap cannot be harvested because
of oncologic margins or because the blood supply has
been compromised from previous procedures, the nasal
septum is separated from the sphenoid rostrum via a
transfi xion incision with a Cottle elevator. A similar
vertical transfi xion incision is performed at a level just
posterior to the nasofrontal recess (this is modifi ed to
include the anterior extent of the tumor). A third septal
transfi xion incision, horizontal and parallel to the fl oor
of the nose, connects these two vertical transfi xion inci-
sions and leaves the bony nasal septum attached to the
cribriform plate. Bilateral wide sphenoidotomies to
remove the entire rostrum help defi ne the posterior
limit of the tumor (planum sphenoidale) and further
delineate the position of the skull base. At this point in
the surgery the skull base from orbit to orbit and from
frontal sinus to sella turcica, as well as the base of the
tumor, is completely exposed and the resection can
begin. The lamina papyracea may be removed as a
lateral margin or as part of an endoscopic medial maxil-
lectomy (unilaterally or bilaterally according to the nec-
essary resection), with care taken to preserve the
periorbita while identifying the anterior and posterior
ethmoidal arteries at their entry into their respective
canals at the skull base. Gentle curettage or drilling
helps remove the bone over the canal, thereby exposing

Chapter 100
Surgery of the Anterior Cranial Base
993
the arteries, which can then be dissected and controlled
with clips or bipolar electrocautery.
Using a high-speed drill with a 2- to 3-mm coarse
diamond hybrid burr, a horizontal osteotomy is made
at the planum sphenoidale, parallel and anterior to the
sphenoid rostrum. Another horizontal osteotomy is
made just posterior to the frontal sinus posterior wall.
These osteotomies are then connected by bilateral oste-
otomies performed lateral to the cribriform plate and
running parallel to the superomedial wall of the orbits,
thereby forming a rectangle surrounding the tumor
and adjacent structures such as the nasal septum, the
entire cribriform plate, and the planum sphenoidale.
The resection then proceeds in an anterior-to-posterior
direction. The olfactory nerves are identifi ed and tran-
sected after bipolar cauterization. If the tumor extends
to the dura, its anterior surface is coagulated with
bipolar cautery and then incised. Dural incisions that
match the previously described osteotomies facilitate
removal of the specimen with adequate control of the
dural margins. It is critical to establish the completeness
of the resection with the use of intraoperative frozen
section analysis. Any positive margin mandates addi-
tional resection.
The crista galli is most often fractured from the rest
of the resected skull base. It must nonetheless be
removed to improve visualization and facilitate the
reconstruction. It should be noted that the crista galli
can extend for a variable depth into the intracranial
cavity, so removal of it involves drilling internally until
it becomes eggshell thin so that it can be fractured.
Meticulous hemostasis completes resection of the ante-
rior cranial base.
This resection may be combined with other
approaches such as a Draf III or endoscopic Lothrop,
with or without endoscopic medial maxillectomy. As
previously stated, the resection can be unilateral to pre-
serve the contralateral turbinates and possibly the olfac-
tory fi bers.
Endoscopic Reconstruction
Currently, we use a subdural inlay graft (between the
brain and dura) of collagen matrix (Duragen, Integra
Life Sciences) to help obliterate the dead space.15,17,19
Its pliability and texture allow manipulation around
neurovascular structures. This subdural graft should
extend beyond the dural margins, ideally by 5 to 10 mm
in all directions. Closely adherent skull base and dura
around the resection margins are dissected. A subse-
quent inlay graft of acellular dermis is placed in the
epidural space (between the dura and skull base). Occa-
sionally, the bony ledges are not adequate to support
an inlay graft; in this case the acellular dermis graft is
placed extracranially (at the nasal side of the defect) as
an onlay graft (Fig. 100-29). All the edges of the defect
should be denuded of mucosa to allow revascularization
of the graft and avoid the formation of mucoceles.
Alternatively, this graft can be sutured to the dura with
nitinol U-clips (Medtronic U-Clips, Memphis, TN).
Although this is an off-label indication for acellular
dermal grafts, we found that its handling characteris-
tics, its availability (i.e., no need for harvesting from a
distant site), ingrowth of the patient’s own tissue, and
rapid epithelialization are advantages that outweigh its
cost. It is important that a single graft with dimensions
that will extend beyond the defect margins in all direc-
tion be used and that the graft be adequately hydrated
in normal saline solution before insertion. It is our
experience that medium-thickness grafts (0.30 to
0.70 µm) offer the best combination of tissue handling
and “take.”
According to the contour of the skull base and how
anterior the extent of the resection is, the acellular
matrix is supported by free abdominal fat or nasal
packing (Fig. 100-30). An abdominal free fat graft har-
vested through a periumbilical incision acts as a bio-
logic dressing and applies pressure to reduce any early
brain herniation that may lead to migration of the
underlying grafts and a subsequent CSF leak. Nasal
packing (1–2 -inch strip gauze impregnated with Bacitra-
Acellular dermis
Acellular dermis
Orbit
Orbit
Orbit
Acellular dermis
Figure 100-29. Endoscopic appearance of acellular dermis used
for skull base reconstruction after endoscopic anterior craniofacial
resection.
Free fat graft
Figure 100-30. Endoscopic appearance of a free fat graft used to
support the endonasal skull base reconstruction.

994
Section 11
Cranial Base Surgery
cin ointment) is preferred if the resection involves the
convexity of the posterior wall of the frontal sinus
because the packing can accommodate for this curva-
ture better than the globular shape of a free fat graft
can. Another alternative is to harvest the fat in a wedge
or teardrop shape that will match the contour of the
skull base more effectively. Recently, we have adopted
the use of a pedicled vascularized fl ap based on the
posterior nasoseptal artery. The technique for harvest
was described earlier. When a vascularized nasoseptal
fl ap is available for reconstruction, it is used as an onlay
fl ap over top of the inlay collagen matrix and acellular
dermis graft. It is critical to separate the grafts from the
packing with some type of nonadherent material such
as Gelfoam or Gelfi lm because this will prevent traction
on the grafts when the packing is removed. In addition,
shifting of the underlying inlay/onlay grafts may occur
during placement of the fat graft or the packing, so the
surgeon must be vigilant and the graft should be placed
under direct visualization with the endoscope. Fibrin
sealants are applied only after the fi nal tissue barrier
has been placed.
We then use the balloon of a 12F Foley catheter to
splint the fat graft or packing, which in turn will stabi-
lize the inlay/onlay grafts and thus further prevent early
brain herniation. The balloon is fi xed in position by
threading the Foley catheter through a Doyle splint,
advancing it to the desired position, and then securing
the Doyle splint to the septum with 4-0 nylon. Place-
ment plus infl ation of the balloon catheter with 5 mL
of saline is also performed under endoscopic vision.
Overinfl ation may result in compressive effects over the
intracranial structures. Any nasal packing or balloons
are removed 3 to 5 days after resection.
POSTOPERATIVE MANAGEMENT
Most patients can be extubated in the recovery room.
After extubation, it is important to avoid external mask
ventilation because air may be forced intracranially
through the anterior cranial base defect. Similarly, all
instrumentation of the nose, including passing of tubes,
should be avoided. A nasal dressing is useful to absorb
any drainage and also to prevent the patient from nose
blowing.
If the patient has a spinal drain and watertight
closure of the dura was achieved intraoperatively, the
spinal drain is usually removed in the recovery room.
This avoids excessive CSF drainage and decreases the
risk of infection. If closure of the dura is tenuous, physi-
ologic drainage of CSF is generally continued for 3 to
5 days. Intermittent drainage of CSF is performed
(approximately 50 mL every 8 hours). This is preferable
to leaving the lumbar drain open to gravity because
excessive CSF drainage may occur with changes in
patient position. Intermittent clamping of the drain
also allows the patient to begin early ambulation.
On the fi rst or second postoperative day, a
follow-up CT scan of the head without contrast
enhancement is obtained to acquire information
about any intracranial complications such as hemor-
rhage or pneumocephalus. This scan also serves as a
basis for future examinations should neurologic symp-
toms develop.
Early ambulation is encouraged, and an oral diet
can usually be instituted on the fi rst postoperative day.
Patients are instructed to not blow their nose. A saline
nasal spray may be used to gently irrigate the nasal
cavity during hospitalization. This spray is continued
after discharge from the hospital. Most patients can be
discharged within 5 to 10 days.
During the month after surgery, excessive instru-
mentation of the nasal cavity is avoided. Gentle suction-
ing of the nasal cavity under endoscopic visualization is
performed while taking care to avoid instrumentation
of the reconstructed cranial base defect. Mucosalization
of the pericranial fl ap occurs within 6 to 8 weeks.
Depending on the original pathology, patients are seen
at periodic intervals to screen for recurrent disease or
complications of surgery. For any patient with a malig-
nant neoplasm, baseline CT or MRI is performed at
approximately 3 months after surgery to allow adequate
time for healing of the surgical site and resolution of
edema or fl uid collections. It serves as a baseline for
future examinations to look for recurrent disease.
Patients may require lifelong nasal hygiene to remove
excessive crusts, especially after radiation therapy.
Patients are instructed to irrigate the nasal cavity with
saline solution via a Water-Pik with a nasal adaptor. An
Alkalol solution may be helpful in loosening crusts.
Because of the loss of olfactory function, patients should
be counseled about the need for in-home monitors to
detect natural gas leaks. Similarly, the home should be
equipped with smoke detectors.
COMPLICATIONS
Metabolic
The fl uid and electrolyte balance of patients undergo-
ing skull base surgery should be monitored closely.
Postoperative hyponatremia is generally the result of
inappropriate fl uid balance in the operating room, but
the syndrome of inappropriate antidiuretic hormone
(SIADH) secretion may develop in patients with cere-
bral edema or contusion. Excessive antidiuretic
hormone (ADH) secretion leads to water retention with
a serum sodium concentration of usually less than
130 mg/dL. The syndrome is generally self-limited and
may be treated by restriction of fl uid to less than
1000 mL/day. If the patient shows signs of disorienta-
tion, seizures, or muscle irritability, 3% saline solution
is administered intravenously.
In contrast, ischemia or trauma to the hypothala-
mus may lead to insuffi cient production of ADH and
result in diabetes insipidus. During diabetes insipidus
the patient loses the ability to concentrate urine, which
leads to increased free water loss and hypernatremia/
hypovolemia. Serum sodium is usually higher than
145 mg/dL, and urine specifi c gravity is less than 1.002.
Careful replacement of fl uids is necessary because urine
output can be greater than 2 L/hr. Aqueous ADH may

Chapter 100
Surgery of the Anterior Cranial Base
995
be replaced initially (2.5 units intramuscularly every 4
hours). Iatrogenic SIADH, through overuse of paren-
teral ADH, should be avoided.
Hyperglycemia is very common in patients receiv-
ing steroids and should be ruled out in any patient with
increased diuresis and hypernatremia. It is treated by a
sliding scale of regular insulin titrated to glycemia.
Other electrolyte disorders such as hypomagnesemia
(<1.8 mg/dL), hypophosphatemia (<2 mg/dL), and
hypocalcemia (<8.0 mg/dL) are common in patients
after skull base surgery, especially if the patient requires
replacement of signifi cant blood loss (>5 units of packed
red blood cells). These disorders can add to the
postoperative delirium and diminished mental state.
Hypocalcemia and hypomagnesemia increase muscle
irritability and can lead to confusion. Calcium is
replaced as 10% calcium gluconate administered intra-
venously at a rate slower than 1 mL/min. Phosphates
are replaced intravenously as a solution containing 10
to 15 mmol phosphate in 250 mL of 5% dextrose solu-
tion administered over a period of 6 hours. Magnesium
may be replaced intravenously as 4 g in 100 mL normal
saline solution given over a 30-minute period.
Vascular
DVT is prevented with the use of sequential compres-
sion stockings. Heparin is contraindicated because of
the risk of postoperative intracranial bleeding. If DVT
occurs, an inferior vena cava fi lter is recommended to
prevent pulmonary embolism. In selected patients at
high risk for DVT or pulmonary embolism, the fi lter is
placed preoperatively.
Coagulopathies may be induced by rapid bleeding
and blood replacement temporarily exhausting the
coagulation factors. This is treated by replacing the
coagulation factors with fresh frozen plasma.
Central Nervous System/Skull Base
Seizures secondary to frontal lobe trauma are rare. Nev-
ertheless, in the presence of signifi cant brain contusion
or when parenchymal resection is necessary, seizure
prophylaxis in the form of phenytoin (Dilantin) is rec-
ommended. Treatment of a grand mal–type seizure
consists of diazepam (Valium), 10 mg intravenously,
and ventilatory support, followed by phenytoin in a 15-
mg/kg loading dose and 5-mg/kg/day maintenance
dose. It is essential to rule out electrolyte or acid-base
imbalances, as well as an intracranial space-occupying
lesion or infl ammation as a cause of the seizures.
CSF leaks that occur in the immediate postopera-
tive period are managed with a lumbar spinal drain.
The drain bag is kept at shoulder level, and 50 mL is
drained every 8 hours. This approximates the physio-
logic production of CSF in 24 hours. Overdrainage may
lead to pneumocephalus. High-fl ow or persistent CSF
leaks (beyond 1 week) require surgical repair. The site
of the leak may be identifi ed by means of a CT-cister-
nogram. Repair of the leak usually involves repair of the
dural defect and the use of a vascularized fl ap to sepa-
rate the leak from the upper aerodigestive tract. Patients
in whom hydrocephalus develops require a ventriculo-
peritoneal shunt.
A small amount of pneumocephalus is frequently
seen in the early postoperative period. It generally
resolves spontaneously over about 1 week. Persistent or
substantial pneumocephalus implies a CSF leak and
may be managed conservatively, as described previously.
Tension pneumocephalus, which is the accumulation
of intracranial air under pressure, may compress brain
tissue and cause impairment of the sensorium or focal
neurologic defi cits (Fig. 100-31). Although the mecha-
nism of the increased air pressure is poorly understood,
it may result from forceful expiration through the nose
when there is an incompletely sealed defect in the ante-
rior cranial base. The pneumocephalus is treated by
needle aspiration when neurologic changes or evidence
of increasing pressure is noted. Recurrent tension
pneumocephalus may require repair of the dura. A
tracheotomy may be used to bypass ventilation.
Wound infection and meningitis are rare complica-
tions of anterior cranial base surgery and are usually the
result of faulty surgical technique. An epidural dead
space often results from cranialization of the frontal
sinus and may increase the risk for a postoperative
wound infection. Antibiotic therapy is directed by Gram
stain or culture and the ability to achieve adequate CSF
penetration. Involvement of bone grafts by the infec-
tion may require their removal. If the bones are not
mobile (repaired with rigid fi xation), they can be sal-
vaged by using a suction irrigation system for the deliv-
ery of local antibiotics. It is essential that separation of
the cranial cavity from the upper aerodigestive tract be
achieved. When bone fl aps are removed because of
infection, the soft tissues are allowed to collapse onto
the underlying tissues (dura or fl ap). Reconstruction is
typically delayed for 6 months to avoid the risk of
osteomyelitis.
Dissection of a galeal-pericranial or galeal scalp fl ap
may compromise the vascularity of the superfi cial scalp
layers, especially in patients who have previously
Figure 100-31. Mental status changes developed in the postopera-
tive period. Computed tomography demonstrated a tension pneumo-
cephalus
that
required
aspiration
to
relieve
frontal
lobe
compression.

996
Section 11
Cranial Base Surgery
received radiation therapy. A constrictive head dressing
should be avoided because it may compromise the
remaining vascularity. With thinning of the scalp, bone
irregularities may become more apparent. Reabsorp-
tion of bone chips may result in depressions at the site
of burr holes. Patients who require postoperative radia-
tion therapy may also experience additional bone
reabsorption.
Encephalocele and pulsatile exophthalmos rarely
occur as late postoperative complications. They are cor-
rected by reoperation and reconstruction of the dural
and bone defects. Loss of medial orbital support and
imprecise realignment of the medial canthus may result
in ocular asymmetry and a disconjugate gaze. Whenever
possible, large orbital defects should be recon -
structed.
References
1. Snyderman CH, Costantino PD, Sekhar LN: Anterior approaches
to the cranial base. In Apuzzo MLJ (ed): Brain Surgery. Complica-
tion Avoidance and Management. New York, Churchill Living-
stone, 1993, pp 2265-2281.
2. Snyderman CH, Sekhar LN, Sen CN, Janecka IP: Malignant skull
base tumors. Neurosurg Clin N Am 1:243-259, 1990.
3. Janecka IP, Sekhar LN: Anterior and anterolateral craniofacial
resection. In Sekhar LN, Janecka IP (eds): Surgery of Cranial
Base Tumors. New York, Raven Press, 1993, pp 147-156.
4. Carrau RL, Snyderman CH, Nuss DW: Surgery of the anterior
and lateral skull base. In Myers EN, Suen JY, Myers JN, Hanna
EYN (eds): Cancer of the Head and Neck, 4th ed. Philadelphia,
WB Saunders, 2003, pp 207-228.
5. Snyderman CH, Carrau RL: Anterior cranial base. In Myers EN
(ed): Operative Otolaryngology–Head and Neck Surgery. Phila-
delphia, WB Saunders, 1997, pp 808-834.
6. Carrau RL, Zimmer L, Myers EN: Neoplasms of the nose and
paranasal sinuses. In Bailey B (ed): Head and Neck Surgery–Oto-
laryngology, 2nd ed. Philadelphia, Lippincott-Raven, 2006, pp
1481-1500.
7. Carrau RL, Segas J, Nuss DW, et al: Squamous cell carcinoma of
sinonasal tract invading the orbit. Laryngoscope 109:230-235,
1999.
8. Carrau RL, Segas J, Nuss DW, et al: Role of skull base surgery for
local control of sarcomas of the nasal cavity and paranasal sinuses.
Eur Arch Otorhinol 251:350-356, 1994.
9. Crist WM, Anderson JR, Meza JL, et al: Intergroup Rhabdomyo-
sarcoma Study-IV: Results for patients with nonmetastatic disease.
J Clin Oncol 19:3091-3102, 2001.
10. Baker KS, Anderson JR, Link MP, et al: Benefi t of intensifi ed
therapy for patients with local or regional embryonal rhabdomyo-
sarcoma: Results from the Intergroup Rhabdomyosarcoma Study
IV. J Clin Oncol 18:2427-2434, 2000.
11. Carrau RL, Snyderman CH, Janecka IP, et al: Role of antibiotic
prophylaxis in cranial base surgery. Head Neck Surg 13:311-317,
1991.
12. Kraus DH, Gonen M, Mener D, et al: A standardized regimen of
antibiotics prevents infectious complications in skull base surgery.
Laryngoscope 115:1347-1357, 2005.
13. Kassam A, Snyderman CH, Mintz A, et al: Expanded endonasal
approach: The rostrocaudal axis. Part II. Posterior clinoids to
foramen magnum. Neurosurg Focus 19(1):E4, 2005.
14. Kassam A, Snyderman CH, Mintz A, et al: Expanded endonasal
approach: The rostrocaudal axis. Part I. Crista galli to the sella
turcica. Neurosurg Focus 19(1):E3, 2005.
15. Kassam A, Carrau RL, Snyderman CH, et al: Evolution of recon-
structive techniques following endoscopic expanded endonasal
approaches. Neurosurg Focus 19(1):E8, 2005.
16. Cavallo LM, Messina A, Cappabianca P, et al: Endoscopic endo-
nasal surgery of the midline skull base: Anatomical study and
clinical considerations. Neurosurg Focus 19(1):E2, 2005.
17. Snyderman CH, Kassam AB, Carrau R, Mintz A: Endoscopic
reconstruction of cranial base defects following endonasal skull
base surgery. Skull Base 17:73-78, 2007.
18. Carrau RL, Kassam AB, Snyderman CH, et al: Endoscopic trans-
nasal anterior skull base resection for the management of sino-
nasal malignancies. Op Tech Otolaryngol Head Neck Surg
17:102-110, 2006.
19. Hadad G, Bassagasteguy L, Carrau RL, et al: A novel reconstruc-
tive technique after endoscopic expanded endonasal approaches:
Vascular pedicle nasoseptal fl ap. Laryngoscope 116:1882-1886,
2006.
PEARLS
• Because of the location of anterior cranial base
pathology, the initial clinical symptoms may be
subtle and are often very similar to chronic
infl ammatory sinus symptomatology.
• Preoperative confi rmation of histopathology is
critical because of the wide variety of pathology of
the anterior cranial base and the treatment options
available.
• Care must be taken when raising a bicoronal fl ap to
not compromise the blood supply from the
supraorbital and supratrochlear vessels to the
pericranial fl ap.
• A basal subfrontal approach is preferred to avoid
excessive retraction of the frontal lobe.
• If undertaking endoscopic resection of anterior
cranial base pathology, oncologic principles should
never be compromised and the same resection must
be achieved endoscopically as would be through a
traditional technique.
PITFALLS
• Elevation of the bicoronal fl ap must occur in a plane
deep to the superfi cial layer of the deep temporal
fascia to avoid injury to the frontal branch of the
facial nerve.
• Failure to preserve the superfi cial temporal vessels
may forfeit the use of a temporoparietal fl ap for
reconstruction.
• All frontal sinus mucosa should be drilled away to
avoid late complications related to retained mucosal
function.
• Lack of a watertight barrier separating the
intracranial contents from the paranasal sinuses may
lead to CSF leakage or infection.
• Early postoperative manipulation of endonasal
reconstruction could lead to an iatrogenic CSF leak.

Chapter 101
Surgical Approaches to the
Infratemporal Fossa
Ricardo L. Carrau, Allan D. Vescan, Carl H. Snyderman, and Amin B. Kassam
The anatomy of the infratemporal fossa (ITF), other-
wise known as the pterygoid fossa, is confusing for both
neurosurgeons and head and neck surgeons. Although
its anatomic description varies, the most accepted
boundaries are shown in Table 101-1.
The fi rst report in the English literature of a surgi-
cal approach to the ITF is attributed to Fairbanks-
Barbosa, who in 1961 described his approach for
advanced tumors of the maxillary antrum.1 Subse-
quently, others reported different surgical techniques
or modifi cations of the Fairbanks-Barbosa approach
(Table 101-2).1-8
PATIENT SELECTION
Tumors may arise in the ITF or may invade it by direct
extension from the upper aerodigestive tract, the
parotid gland, the temporal bone, the skull base, or the
cranial cavity. It is fundamental that the origin and
extension of the tumor be established to offer the
patient the most effective treatment.
Selection of the surgical approach depends on the
characteristics of the patient, the biologic behavior of
the tumor, and the experience of the surgeon. In most
instances, these tumors require a multidisciplinary
approach to properly stage, diagnose, and extirpate the
tumor and to provide an acceptable cosmetic and func-
tional reconstruction.
Clinical Evaluation
The history and physical examination must emphasize
neurologic defi cits, especially those resulting from dys-
function of the cranial nerves. These defi cits are an
important consideration in the development of a surgi-
cal plan, as well as postoperative care, because they have
a signifi cant impact on recovery and functional reha-
bilitation of the patient. As a result of the location of
these tumors, considerable growth may occur before
obvious clinical fi ndings develop and the patient seeks
medical care. The initial symptoms are diverse and are
usually secondary to dysfunction of the masticatory
muscles or cranial nerve defi cits.
Symptoms and signs that are attributable to defi cits
of the trigeminal nerve are frequently evident. Pain may
be present in the distribution of any of the divisions of
the trigeminal nerve and may be exacerbated by jaw
movement, jaw clenching, or head position. Sensory
losses characterized by hypoesthesia or paresthesia of
the divisions of the trigeminal may be present, and the
pattern of defi cits provides clues to the location and
extent of the tumor. Pain may be referred to the ear
because of sensory innervation of the external auditory
canal (EAC).
Physical examination focuses on sensory and motor
defi cits. In addition to assessing cutaneous sensation,
corneal sensation is tested with a cotton swab. In the
presence of a concomitant facial nerve palsy, protective
measures to prevent corneal injury may need to be
instituted preoperatively or postoperatively. Trigeminal
motor function is assessed by palpation of the mastica-
tory muscles (masseter and temporalis) during jaw
clenching. Deviation of the jaw laterally with jaw opening
refl ects dysfunction of the pterygoid musculature.
Trismus may be due to mechanical restriction of the jaw
as a result of infi ltration of tumor into the pterygoid
muscles or temporomandibular joint (TMJ), or it can
be due to pain. The extent and cause of the trismus are
important considerations in the perioperative manage-
ment of the airway. Trismus secondary to pain will dis-
appear with general anesthesia and allow safe oral
997

998
Section 11
Cranial Base Surgery
Table 101-1
ANATOMIC BOUNDARIES OF THE INFRATEMPORAL FOSSA
Superior
Medial
Lateral
Anterior
Posterior
Bone
Greater wing of the
sphenoid, temporal
bone
Lateral pterygoid
plate,
pterygopalatine
fi ssure
Mandible
Zygoma
Articular tubercle of the
temporal bone, glenoid
fossa and condyle,
styloid process
Muscle
Superior
constrictor,
pharyngobasilar
fascia
Masseter
temporalis
Lateral and
medial
pterygoid,
masseter
Prevertebral fascia
Foramina
Carotid canal
Jugular foramen
Foramen ovale
Foramen spinosum
Foramen lacerum
Soft tissue
Muscles
Nerves
Foramen ovale (V3),
jugular foramen (pars
nervosa)
IX-XI
Sympathetic plexus
Vessels
Internal carotid artery
Internal maxillary
artery
Internal carotid artery
Internal jugular vein
Pterygoid venous
plexus
Jugular vein
Other
Parotid
Table 101-2
SURGICAL APPROACHES TO THE
INFRATEMPORAL FOSSA:
HISTORICAL BACKGROUND
Authors*
Year
Technique
Fairbanks-Barbosa1
1961
Extracranial resection of
advanced tumors of the
antrum
Terz et al.2
1969
Craniofacial resection of
tumors of the SNT with
invasion of the ITF
Fisch3
1979
ITF approaches for
tumors of the upper
aerodigestive tract or
intracranial tumors
invading the ITF
Biller et al.4
1981
Median mandibulotomy
Sekhars et al.5
1987
Subtemporal-preauricular
approach
Cocke et al.6
1990
Extended maxillotomy/
maxillectomy approach
Janecka et al.7
1990
Facial translocation
approach
Catalano and
Biller8
1993
Vascularized facial
translocation
*Many other authors have contributed immensely to the
advancement of surgery of the ITF. This table is intended to
present an overview of what we consider novel approaches and is
by no means comprehensive.
ITF, infratemporal fossa; SNT, sinonasal tract.
endotracheal intubation. Awake nasotracheal intuba-
tion may be performed in patients with constant trismus
if it is anticipated that surgery will correct the trismus.
Otherwise, awake tracheostomy should be performed at
the beginning of surgery.
Facial nerve defi cits may be manifested as facial
weakness, epiphora, hyperacusis, hyperkinesis, and dys-
geusia. The motor function of all divisions of the facial
nerve is assessed. It is important to remember, however,
that signifi cant involvement of the facial nerve by tumor
may occur before any facial weakness is clinically appar-
ent. Defi cits of the facial nerve or fi rst division of the
trigeminal nerve (V1), or both, may result in corneal
exposure. Insertion of a gold weight in the upper eyelid
or tightening of the lower lid may be necessary to
protect the cornea and prevent future complications.
Hearing loss may be either conductive or sensori-
neural. Conductive hearing loss is usually a result of
eustachian tube dysfunction with accumulation of fl uid
in the middle ear space. Sensorineural hearing loss may
result from tumor involvement of the temporal bone or
posterior cranial fossa. The presence of hearing loss
may be helpful in localizing the tumor, especially when
it is observed in combination with other cranial nerve
defi cits. Because hearing loss impairs effective commu-
nication with the patient during the perioperative
period, the use of a hearing aid or other amplifi cation
device may be required for communication. It should
be anticipated that extensive surgery involving the infra-
temporal skull base will result in a conductive hearing
loss that may compound a previous sensorineural
hearing loss.

Chapter 101
Surgical Approaches to the Infratemporal Fossa
999
Defi cits of the lower cranial nerves (IX, X, XI, and
XII) are seen with tumors that arise high in the para-
pharyngeal space near the jugular foramen. Patients
may exhibit varying degrees of hypernasal speech, nasal
regurgitation, dysphagia, aspiration, and dysphonia.
Findings on physical examination include decreased
elevation of the palate, decreased mobility of the tongue
with deviation to the involved side on protrusion,
pooling of secretions in the hypopharynx, decreased
supraglottic sensation, ipsilateral vocal cord paralysis,
and decreased prominence and strength of the sterno-
cleidomastoid and trapezius muscles. In patients with
incomplete lower cranial nerve defi cits, surgical therapy
can be expected to increase nerve dysfunction with
resultant increased risks of dysphagia and aspiration.
Consequently, a tracheostomy is often necessary in the
perioperative period. Laryngeal framework surgery
(thyroplasty) may be considered at the same time to
improve glottic closure and decrease the risk of aspira-
tion. Strong consideration should also be given to
placement of a gastrostomy (percutaneous or open) to
facilitate postoperative feeding and decrease the risk of
aspiration. Palatal dysfunction may be ameliorated by a
palatal lift prosthesis to push the soft palate against the
posterior pharyngeal wall. Alternatively, a pharyngeal
fl ap or surgical fi xation of the palate to the pharyngeal
wall (palatopexy) may be necessary.
Because of the relative inaccessibility of the infra-
temporal space to physical examination, radiologic
imaging is an essential part of the evaluation. Both
computed tomography (CT) and magnetic resonance
imaging (MRI) provide valuable information and are
performed with a standard skull base protocol. CT scan-
ning provides adequate resolution of most tumors and
is superior for demonstrating enlargement of neural
foramina or erosion of bone. For most tumors involving
the ITF, MRI provides better resolution of soft tissue
planes and tumor invasion along neural and vascular
structures (Fig. 101-1). CT and MRI are often comple-
mentary in the evaluation of cranial base tumors.
A critical question in the evaluation of tumors in
this area is the relationship of the neoplasm to the
internal carotid artery (ICA). Magnetic resonance angi-
ography (MRA) may be used in selected cases to provide
a noninvasive assessment of the ITF and intracranial
vasculature. If preoperative embolization of the tumor
is warranted, as is the case for many juvenile angiofi bro-
mas, paragangliomas, or other highly vascularized
tumors, angiography is preferable to MRA because the
tumor can be embolized during the initial angiogram
(Fig. 101-2). In addition to yielding information about
tumor vascularity and involvement of the ICA, angiog-
raphy provides important information on the intracra-
nial circulation and collateral blood supply. Neither
study is adequate, however, to reliably assess the ade-
quacy of collateral intracranial circulation in the event
that manipulation or sacrifi ce of the ICA is necessary.
Whenever manipulation of the ICA is likely, evaluation
of collateral cerebral blood fl ow with angiography–
balloon
occlusion–xenon
computed
tomography
(ABOX-CT) is recommended (Fig. 101-3).
Briefl y, ABOX-CT consists of the introduction of a
nondetachable balloon into the ICA. The balloon is
infl ated for 15 minutes, and the awake patient is moni-
tored for sensory, motor, or higher cortical function
defi cits. The balloon is defl ated and the patient is trans-
ferred to a standard CT suite. The balloon is then rein-
fl ated and a mixture of 32% xenon and 68% oxygen is
administered to the patient via facial mask for 4 minutes.
The CT scan will demonstrate the distribution of xenon
within cerebral tissue, which refl ects blood fl ow (Fig.
101-4). This study provides a quantitative assessment of
millimeters of blood fl ow per minute per 100 g of brain
tissue. This test accurately predicts patients at risk for a
cerebrovascular accident when blood fl ow through the
ICA is compromised (Table 101-3).9 It should be recog-
nized that patients can still suffer ischemic brain injury
despite negative ABOX-CT fi ndings because of embolic
phenomena or the loss of collateral vessels, which are
not assessed by balloon occlusion testing. For these
reasons, every attempt is made to preserve or recon-
struct the ICA when feasible. Other techniques that
provide similar information regarding collateral cere-
bral blood fl ow include single-photon emission com-
puted tomography (SPECT) with balloon occlusion
and transcranial Doppler monitoring.
Biopsy
Histologic confi rmation is mandatory before subjecting
the patient to any major extirpative surgery. Tissue is
usually obtained by incisional or punch biopsy. Occa-
Figure 101-1. Magnetic resonance image demonstrating a neuri-
lemmoma arising from the mandibular division of the trigeminal
nerve (arrow). Although there is intracranial extension of the tumor,
it is extradural. Tumors in this location may reach a large size before
they are visible or palpable on physical examination. Such tumors
may cause facial numbness, pain, or diffi culty with mastication.

1000
Section 11
Cranial Base Surgery
sionally, fi ne-needle aspiration biopsy under CT or MRI
guidance is required for tumors arising in deep loca-
tions. Biopsy of many cranial base tumors can be per-
formed with minimally invasive endoscopic approaches
through the paranasal sinuses.
The surgeon should consider the possibility of
metastasis to the cranial base when the tumor appears
to originate from the bone and is in an unusual loca-
tion. In such cases, a thorough history and physical
examination will usually provide evidence of a primary
A
B
Figure 101-2. Angiography of
the left internal maxillary artery in
a patient with an angiofi broma
demonstrates
an
extensive
tumor blush (A) that is markedly
decreased after embolization (B).
Figure 101-3. Magnetic resonance image demonstrating a neo-
plasm of the right infratemporal skull base that is encasing the
petrous portion of the internal carotid artery (ICA) (arrow). Preopera-
tive evaluation of collateral cerebral blood fl ow with angiography–
balloon occlusion–xenon computed tomography is recommended
because of the increased risk of injury to the ICA with attempted
removal of this tumor.
tumor elsewhere (breast, prostate, lung, or gastrointes-
tinal system). Although the cost-effectiveness of an
extensive search in asymptomatic patients is question-
able, a screening test such as a mammogram or serum
prostate-specifi c antigen level may be revealing. The
search for a primary tumor or other metastases should
be intensifi ed when a biopsy reveals an adenocarcinoma
that is not originating from a major salivary gland.
“Intestinal-type” adenocarcinomas of the nasopharynx,
1
2
3
Figure 101-4. After balloon occlusion of the left internal carotid
artery (ICA), a signifi cant reduction in blood fl ow was noted in the
distribution of the left anterior and middle cerebral arteries (1-3).
This patient is at high risk for development of a stroke after perma-
nent occlusion of the left ICA.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1001
in particular, can be confusing and may necessitate
thorough evaluation of the lower gastrointestinal
tract.
Metastatic Workup
The extent of the evaluation to rule out regional or
distant metastasis is dictated by the suspected histologic
type and stage of the tumor. CT or MRI of the neck is
considered more sensitive than physical examination
for the detection of regional metastases. Patients with
tumors showing a predilection for hematogenous
metastasis (sarcomas, melanoma) should undergo a CT
scan of the chest and abdomen and a bone scan. A
positron emission tomographic (PET) scintigram may
aid in identifying both the primary and metastatic
tumors. A lumbar puncture for cerebrospinal fl uid
(CSF) cytology is reserved for patients with tumors
invading the dura or with symptoms of “drop metasta-
sis” to the spinal cord. Consultation with an experi-
enced neurosurgeon is recommended for tumors
invading the skull base or for tumors that require resec-
tion of the skull base for margins.
Reconstructive/Rehabilitation
Considerations
Finally, the reconstructive requirements of oncologic
surgery should be anticipated. In most cases, a tempo-
ralis muscle transposition fl ap is adequate to separate
the cranial cavity from the upper aerodigestive tract and
obliterate the dead space. Nevertheless, the use of
microvascular free fl aps such as the rectus abdominis
fl ap (for soft tissue defects), latissimus dorsi fl ap (for
myocutaneous or massive defects), or iliac and scapular
composite fl aps (for defects requiring bone reconstruc-
tion) is recommended when the temporalis muscle or
its blood supply will be sacrifi ced, when the patient
requires complex resection involving composite tissue
fl aps with skin or bone, or when the extirpative surgery
produces a massive soft tissue defect and dead space.
Attention should also be directed to functional and
cosmetic defi cits created by the tumor and surgery.
Facial rehabilitation may be achieved during the primary
surgery. When a temporary facial palsy is anticipated,
corneal protection with lubricants or a temporary lateral
tarsorrhaphy is generally adequate. When grafting of
the facial nerve is necessary and a longer period of
recovery of facial nerve function is expected, implanta-
tion of a gold weight into the upper eyelid is performed.
If reconstruction of the facial nerve is not feasible, static
fascial slings or muscle transpositions are appropriate.
Lower cranial nerve defi cits may be ameliorated by
laryngeal framework surgery, tracheotomy, or laryngo-
tracheal separation.
PREOPERATIVE PLANNING
The patient is premedicated with a short-acting benzo-
diazepine. Narcotics may be used in the absence of
elevated intracranial pressure. Preoperative steroids are
administered if manipulation of the brain or motor
cranial nerves is anticipated. H2-blockers or proton
pump inhibitors are given perioperatively to decrease
the incidence of gastroesophageal refl ux and stress
ulcers. If retraction of the temporal lobe is necessary,
prophylactic anticonvulsants are administered during
surgery and in the postoperative period.
Preoperatively, the patient’s blood is typed and
cross-matched for 4 to 6 units of packed red blood cells
or cryoprecipitate. A Cell Saver/autotransfusion device
may be used when the tumor is benign and there is no
contamination by fl ora of the upper aerodigestive
tract.
Perioperative antibiotic prophylaxis that provides
coverage against the fl ora of the skin and upper aerodi-
gestive tract and exhibits good penetration of the blood-
brain barrier is administered 2 hours before surgery
and continued for 48 hours after the surgery is com-
pleted. The use of a broad-spectrum cephalosporin with
good CSF penetration (e.g., ceftriaxone) appears to be
as effective as multiple antibiotic regimens.
The patient is taken to the operating room, and all
standard monitoring electrodes and lines are placed
and secured (Table 101-4). The choice of anesthetic
agent depends on the extent of intracranial dissection
and the potential for brain injury, systemic hemody-
namics, the need for monitoring of cortical and brain
stem functions (e.g., brain stem evoked response,
somatosensory evoked potentials, electroencephalogra-
phy), and the need for cranial nerve monitoring (7th
and 10th through 12th cranial nerves). Somatosensory
evoked potential monitoring using the median nerve is
indicated whenever surgical manipulation of the ICA is
anticipated.
Table 101-3
XENON COMPUTED TOMOGRAPHY
Cerebral
Blood Flow
(mL/min/
100 g Tissue)
Risk
Implication
<20
High
Patient will not tolerate
occlusion of the internal
carotid artery
21-35
Moderate
Patient will tolerate
occlusion under controlled
circumstances;
reconstruction is
recommended
>35
Low
Carotid may be sacrifi ced
Table 101-4
STANDARD ANESTHETIC
MONITORING
Electrocardiogram
Pulse oximeter
Capnometer
Arterial line
Central venous catheter*
*In selected cases, a pulmonary artery catheter may be
necessary.

1002
Section 11
Cranial Base Surgery
When changes in head position during surgery are
anticipated, the endotracheal tube is secured with a
circumdental or circum-mandibular wire ligature (no.
26 stainless steel wire). The operating table is posi-
tioned perpendicular and away from the anesthetic
equipment. If signifi cant brain retraction or intradural
dissection is expected, a spinal drain is placed and
secured with sutures and adhesive dressing (e.g., Tega-
derm, Op-Site). Other measures to diminish intracra-
nial pressure, such as hyperventilation, osmotic diuresis,
or steroids, are used as needed throughout surgery. A
nasogastric tube and Foley catheter are passed and
secured after adequate placement is corroborated.
Antiembolic sequential compression stockings are man-
datory to diminish the risk for deep venous thrombosis.
Heparin is not recommended because of the potential
for increased intracranial bleeding.
The head of the patient is positioned on a Mayfi eld
horseshoe head holder or, if necessary for intracranial
neurovascular work, on Mayfi eld pins. When the horse-
shoe is used, it is important that additional “egg crate”
foam padding be used, because scalp ischemia may
result from the hard rubber pads during prolonged
surgery. The head should be positioned in slight exten-
sion to provide access to the neck for proximal control
of the ICA. Monitoring electrodes are carefully placed
and secured with sutures or staples. A baseline record-
ing is obtained for intraoperative reference. Tarsorrha-
phy sutures are placed for protection of the eyes. Ribbon
gauze or pledgets soaked in oxymetazoline (0.05%)
solution may be inserted intranasally at this time for
additional hemostasis if communication with the nasal
cavity is anticipated. The proposed incision lines are
infi ltrated with local anesthetic containing epinephrine
(1:200,000). The hair is parted with a comb and held
in place with staples. Standard skin preparation with
povidone-iodine (Betadine) solution is performed.
SURGICAL TECHNIQUE
Preauricular (Subtemporal) Approach
This approach is suited for tumors arising in the ITF
and intracranial tumors arising in boundaries of the
anterior temporal bone or greater wing of the sphenoid
bone and extending into the ITF.10-13 The preauricular
approach does not allow safe resection of any portions
of the tympanic bone or control of the infratemporal
facial nerve or jugular bulb.
A hemicoronal or bicoronal incision across the
vertex of the scalp and posterior to the hairline is
extended through the subcutaneous tissue, galea, and
pericranium over the cranium (Fig. 101-5A). In the
temporal area, the incision extends down to the deep
layer of the temporal fascia overlying the temporalis
muscle. Ipsilateral to the tumor, the incision is extended
into the preauricular area. A separate incision may be
made in the neck for proximal control of the carotid
arteries (see Fig 101-5B).
The scalp fl ap is elevated anteriorly in a subpericra-
nial plane to separate attachments of the pericranium
Temporoparietal fascia
Loose areolar tissue
Temporalis
muscle
A
B
Temporal
fat pad
Masseter muscle
Zygomatic
arch
Buccal fat
pad
Facial nerve
Superficial layer of
deep temporal fascia
Deep layer of deep
temporal fascia
Parotid-masseteric
fascia
Figure 101-5. A, A hemicoronal scalp incision is made posterior to
the hairline in the temporal area and extended along a preauricular
skin crease, similar to a parotidectomy incision. It may be continued
into the upper cervical region, or a separate cervical incision may be
made for exposure of the vessels and nerves. B, The different tissue
planes of the temporal area are illustrated. The frontal branch of the
facial nerve is found in the superfi cial layer of the deep temporal
fascia. Safe dissection must occur deep to this plane.
to the deep layer of the temporal fascia at the margin
of the temporalis muscle down to the level of the supe-
rior orbital rim. The anterior branches of the superfi -
cial temporal artery are preserved to ensure adequate
blood supply to the scalp fl ap. The scalp fl ap is easily
elevated from the deep temporal fascia with a broad
periosteal elevator. Approximately 1 to 2 cm above the
zygoma the fascia splits into superfi cial and deep layers
that attach to the lateral and medial surfaces of the
zygomatic arch, respectively. This creates a triangular

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1003
space fi lled with adipose tissue. The superfi cial layer of
the deep temporal fascia is incised obliquely above the
level of the superior orbital rim toward the zygomatic
root. Dissection is then carried deep to this plane, and
the superfi cial layer of the deep temporal fascia and the
adipose tissue are elevated off the zygomatic arch and
refl ected anteriorly with the fl ap. The orbitozygomatic
complex is exposed by subperiosteal dissection. This
maneuver protects the frontal branches of the facial
nerve that are superfi cial to the superfi cial layer of the
deep temporal fascia (Fig. 101-6). Periosteum is ele-
vated from the lateral surface of the zygomatic arch and
malar eminence. The periorbita is elevated from the
lateral orbit with a Freer or Adson elevator to expose
the area from the roof of the orbit to the inferior orbital
fi ssure. It is helpful to separate the masseteric fascia
from the overlying parotid gland with a broad perios-
teal elevator before detaching the masseter muscle
from the zygomatic arch (Fig. 101-7). The masseteric
fascia is transected at its insertion into the zygomatic
arch, and the periosteal elevator is then used to sepa-
rate it from the muscle while leaving it attached to the
deep surface of the parotid.
All soft tissue anterior to the temporal bone can be
transected to the level of the facial nerve pedicle to
increase the arc of rotation of the fl ap. The facial nerve
is identifi ed and preserved with a standard technique
(see Chapter 62). It is helpful to leave a pedicle of soft
tissue around the facial nerve trunk to prevent excessive
traction injury to the facial nerve with retraction of the
facial fl ap. The attachments of the temporalis and mas-
seter muscles to the zygomatic arch are transected with
electrocautery. Using the caudal limb of the incision,
the sternocleidomastoid muscle is dissected laterally
and the carotid sheath is exposed. The internal,
common, and external carotid arteries, as well as the
internal jugular vein, are exposed, dissected, and con-
trolled. Cranial nerves X through XII are identifi ed
and preserved. Vessel loops are placed around the
structures and secured with hemoclips rather than
hemostats to avoid inadvertent traction on a hemostat
(Fig. 101-8).
The attachments of the temporalis muscle to the
pericranium are transected with electrocautery, and the
Figure 101-6. The scalp fl ap is elevated from the underlying
cranium, deep temporal fascia, lateral orbital rim and zygomatic arch,
and masseteric fascia. The plane of dissection is deep to the parotid
gland and the temporal branches of the facial nerve. (Redrawn from
Sekhar LN, Janecka IP [eds]: Surgery of Cranial Base Tumors. New York,
Raven Press, 1993.)
Figure 101-7. In this cadaver dissection, the masseteric fascia and
other fascial attachments to the zygomatic arch are separated after
elevation of the facial soft tissues from the superfi cial surface of the
masseteric fascia. This frees the zygomatic arch for performance of
the osteotomy.
Figure 101-8. The nerves and vessels of the right upper cervical
region have been isolated in this patient (left superior). White vessel
loops are placed around the hypoglossal, vagus, and spinal accessory
nerves. A dark vessel loop is placed around the internal carotid
artery.

1004
Section 11
Cranial Base Surgery
muscle is elevated off the temporal fossa. If the muscle
will be returned to its original position at the comple-
tion of surgery, a few millimeters of fascia may be left
attached to the cranium at the margin of the muscle to
facilitate suturing of the muscle. The temporal muscle
is then refl ected inferiorly until the infratemporal crest
is fully visualized. Bleeding from underlying bone is
usually encountered and controlled by the application
of bone wax. Care should be exercised when dissecting
on the deep surface of the temporalis muscle near its
attachment to the mandible because the blood supply
to the muscle (deep temporal arteries from the internal
maxillary artery) may be injured. Dissection of soft
tissue from the infratemporal skull base is associated
with troublesome bleeding from the pterygoid plexus.
It can be controlled with bipolar electrocautery and the
application of hemostatic materials. A subtemporal cra-
niectomy is performed at this time to aid in identifi ca-
tion and exposure of the neural and vascular foramina.
The coronoid process can be fractured or removed to
increase the inferior arc of rotation of the temporal
muscle. It is important to protect the soft tissue at the
sigmoid notch to prevent accidental injury to the inter-
nal maxillary artery at the point where it travels on the
medial surface of the mandibular ramus.
The orbitozygomatic bone graft is freed by osteoto-
mies at the zygomatic root posteriorly, the zygomatico-
frontal suture superiorly, and the zygomaticomaxillary
buttress at the level of the zygomaticofacial nerve medi-
ally (Figs. 101-9 and 101-10). A reciprocating saw is used
to make beveled and V-shaped bone cuts to maximize
exposure and facilitate replacement of the bone graft
at the completion of surgery. If there is tumor involve-
ment of the orbit, the bone cut through the lateral wall
of the orbit may include only the orbital rim to avoid
violation of the tumor. For lesions that do not involve
the temporal bone or petrous portion of the ICA, this
approach provides adequate exposure to the infratem-
poral skull base. If dissection of the ICA throughout its
petrous portion is necessary, the glenoid fossa is
removed as part of the bone graft. It is fi rst necessary
to perform a temporal craniotomy for exposure of the
superior aspect of the glenoid fossa (Fig. 101-11). The
capsule of the TMJ is dissected free from the fossa and
displaced inferiorly. If possible, the capsule and menis-
cus are preserved. If additional exposure is necessary,
the mandibular condyle can be transected at the level
of the sigmoid notch and removed (Fig. 101-12). Using
a reciprocating saw, a V-shaped cut is then made through
the bone of the glenoid fossa to incorporate approxi-
mately the lateral two thirds of the glenoid fossa (Fig.
101-13). This avoids potential injury to the ICA, which
Figure 101-9. The areas of bone removal are noted (dark stippled
area). A temporal craniotomy is performed in conjunction with an
orbitozygomatic osteotomy. This illustration demonstrates transec-
tion of the zygomatic arch anterior to its posterior attachment and
preservation of the lateral orbital rim. Additional exposure of the
infratemporal skull base may be achieved by removal of the subtem-
poral cranium (striped area) and resection of the mandibular condyle
(light stippled area).
Figure 101-10. In this plastic model of a skull, the lines for the
craniotomy and orbitozygomatic osteotomy are marked. If it is not
necessary to remove the glenoid fossa, the zygomatic arch is tran-
sected posteriorly at its attachment to the cranium.
Figure 101-11. A temporal craniotomy has been performed to
provide adequate exposure for osteotomies through the glenoid fossa
and orbital walls.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1005
A
B
Figure 101-12. A, An osteotomy of the mandibular condyle is
performed with a reciprocating saw to provide additional exposure.
B, Removal of the coronoid process in conjunction with the condyle
provides further exposure and facilitates rotation of the temporalis
muscle.
Figure 101-13. The lateral two thirds of the glenoid fossa is
removed by performing osteotomies with a reciprocating saw. Care is
taken to avoid injury to the internal carotid artery medially and the
cochlea posteriorly.
Figure 101-14. The location of the internal carotid artery (plastic
tube) is noted in this model to be medial to the mandible and the
glenoid fossa.
is located medial to the glenoid fossa (Fig. 101-14). If
the bone cut is made too posteriorly, there is risk
of injury to the cochlea. This modifi cation provides
better stability for the mandibular condyle after
reconstruction.
Elevation of the periorbita from the lateral and
inferior walls of the orbit is necessary to identify the
inferior orbital fi ssure and complete the orbitozygo-
matic osteotomies (Fig. 101-15). The tip of the recipro-
cating saw is placed in the most lateral aspect of the
inferior orbital fi ssure along the orbital fl oor, and an
osteotomy through the malar eminence is performed
(Fig. 101-16). This separates the zygoma from the lateral
wall of the maxilla. On occasion, violation of the maxil-
lary sinus may occur, especially if the maxilla is well
pneumatized. If this happens, the mucosal remnant
attached to the zygoma is removed. Adequate closure
of the maxillary defect is achieved after replacement
of the orbitozygomatic bone segment at the completion
of surgery. It is not necessary to strip the mucosa
from the remainder of the sinus. Using both intracra-
nial and extracranial approaches, osteotomies are
made through the superior and lateral orbital walls to
completely free the orbitozygomatic bone segment
(Fig. 101-17). This provides excellent access to the
infratemporal skull base, orbital apex, and lateral
maxilla (Fig. 101-18).
Several anatomic relationships are useful for iden-
tifi cation of infratemporal skull base structures (Fig.
101-19). After completion of the temporal craniotomy,
additional bone is removed from the inferior margin of
the defect with rongeurs (see Fig. 101-9). The origin of
the lateral pterygoid plate from the skull base is identi-
fi ed anteriorly. The curve of the lateral pterygoid plate

1006
Section 11
Cranial Base Surgery
A
B
C
Figure 101-15. The osteotomies communicate with the lateral
aspect of the inferior orbital fi ssure (arrow).
Figure 101-16. An osteotomy is made from the inferior orbital
fi ssure across the malar eminence and lateral to the maxilla.
Figure 101-17. With the use of intracranial and extracranial approaches,
osteotomies of the superior orbital roof (A and B) and lateral orbital wall (C)
are performed.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1007
ovale may be controlled with Surgicel packing. If com-
plete dissection of the petrous portion of the ICA is
required, it is usually necessary to transect the mandibu-
lar division of the trigeminal nerve at the foramen ovale
for additional exposure (Fig. 101-20). The lateral aspect
of the sphenoid sinus may be accessed by removal of
bone between the second and third divisions of the tri-
geminal nerve (Fig. 101-21). Extirpation of the tumor
can now proceed, including the involved soft tissue and
bone (Fig. 101-22). For tumors invading the mandible,
partial mandibulectomy is essential to obtain negative
margins. In the pediatric age group, the distance from
the body of the mandible to the infratemporal skull
base is greatly foreshortened. Adequate exposure of the
infratemporal skull base can often be achieved from a
transcervical approach with superior displacement of
the facial nerve (Fig. 101-23).
After extirpation of the tumor, it is necessary to
close any defects that are communicating with the
upper aerodigestive tract (Fig. 101-24). If the blood
supply to the temporalis muscle is preserved, transposi-
tion of the temporalis muscle provides obliteration of
the dead space, as well as protection of the ICA (Fig.
101-25). Because of the branching pattern of the blood
supply to the temporalis muscle, the anterior one half
Figure 101-18. Extent of exposure after a temporal craniotomy
and orbitozygomatic osteotomy.
Figure 101-19. Skull demonstrating the anatomic relationships of
the internal carotid artery (ICA) and carotid canal. The foramen
ovale (straight arrow; white vessel loop) and foramen spinosum (arrow-
head; short dark vessel loop) are in a direct line from the lateral
pterygoid plate to the spine of the sphenoid. The ICA (long dark
vessel loop) courses through the carotid canal medial to the eusta-
chian tube (curved arrow) and the glenoid fossa. The mandible has
been disarticulated to reveal the glenoid fossa.
is followed posteriorly to identify the foramen ovale,
foramen spinosum, and the spine of the sphenoid bone.
These structures lie in a straight line and are all lateral
to the ICA. The middle meningeal artery is cauterized
with bipolar electrocautery and transected. Bleeding
from venous communications through the foramen
Figure 101-20. Illustration demonstrating a tumor medial to the
mandibular division of the trigeminal nerve and in close proximity
to the petrous portion of the internal carotid artery (ICA). Additional
exposure of the ICA and removal of the tumor often necessitate
transection of the mandibular division of the trigeminal nerve.
(Redrawn from Sekhar LN, Janecka IP [eds]: Surgery of Cranial Base Tumors.
New York, Raven Press, 1993.)

1008
Section 11
Cranial Base Surgery
or lateral portion of the muscle may be transposed with
its blood supply intact (Fig. 101-26). The remaining
portion of the muscle is used to fi ll in the anterior
portion of the temporal defect. Defects of the orbit may
be obliterated by temporalis muscle transposition with
skin grafting (Fig. 101-27). In some circumstances, ante-
riorly or posteriorly based pericranial scalp fl aps may
be elevated to provide protection of the infratemporal
skull base. In the absence of the temporalis muscle,
large soft tissue defects are best reconstructed with
microvascular free tissue transfers (Fig. 101-28). The
orbitozygomatic bone graft is then replaced and held
in position with titanium microplates. If resection of the
mandibular condyle is necessary for exposure of the
petrous ICA, reconstruction of the TMJ is not attempted.
Reconstruction has not been shown to improve postop-
erative function and may actually contribute to scarring
and postoperative trismus. Standard closure of soft
tissues is performed.
Postauricular (Transtemporal) Approach
The postauricular approach is ideal for lesions involv-
ing the temporal bone and extending into the ITF.10,11
A “question mark” or C-shaped incision is started in the
temporal area, extended postauricularly into the
mastoid region, and curved down to follow one of
the midneck horizontal skin creases (Fig. 101-29). If
middle ear function is going to be sacrifi ced as part
of the approach or tumor resection and there is a risk
of a postoperative CSF leakage, the EAC is closed per-
manently to prevent CSF otorrhea. The EAC is divided
Figure 101-21. Illustration demonstrating an opening into the
sphenoid sinus medial to the transected second division of the tri-
geminal nerve. A segment of the petrous portion of the internal
carotid artery has been exposed. (Redrawn from Sekhar LN, Janecka IP
[eds]: Surgery of Cranial Base Tumors. New York, Raven Press, 1993.)
C
B
D
A
C
B
D
Figure 101-22. A, Computed
tomography scan demonstrating
recurrent adenocarcinoma of the
left infratemporal fossa that is
encasing the mandible and extend-
ing to the lateral aspect of the
internal carotid artery (ICA). B, A
left
infratemporal
skull
base
approach was used with excision of
the previous scar. C, The resected
specimen included the ramus and
condyle of the mandible, the
parotid gland and associated soft
tissue, the pterygoid musculature,
and the left neck contents. The
medial limit of the resection was
the extracranial portion of the
ICA. D, Excellent healing of the
surgical site is noted after comple-
tion of postoperative neutron
beam therapy. Some permanent
hair loss has occurred secondary to
the radiation therapy.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1009
A
B
C
Figure 101-23. A, A 4-month-old infant had a large teratoma of
the right parapharyngeal space with extension to the skull base and
into the cervical region. B and C, The tumor was successfully removed
via a transcervical approach, with preservation of facial nerve
function.
at the bony–cartilaginous junction and then closed with
everting stitches. This closure is reinforced with a myo-
periosteal U-shaped fl ap based on the posterior margin
of the EAC. Occasionally, closure of the EAC may be
necessary in patients with a preexisting tympanotomy
tube. Alternatively, the canal may be preserved by
placing the incisions in the conchal area (Fig. 101-30).
The incision follows the margin of the conchal bowl
and tragus so that the scar will be camoufl aged. In the
conchal area, the skin, cartilage, and perichondrium
are incised to communicate with the retroauricular
plane of dissection. These incisions allow anastomosis
of the EAC to the pinna at the end of the extirpative
procedure (Fig. 101-31). An incision within the EAC is
not used because it is diffi cult to suture and obtain a
watertight closure and there is a risk of postoperative
stenosis. A Penrose drain can be inserted through the
defect in the skin fl ap to provide gentle retraction (Fig.
101-32). The remaining conchal bowl and tragus may
be sutured together temporarily to provide better expo-
sure of the operative fi eld.
The cervicofacial fl ap is elevated in a subplatysmal
plane in the cervical area, lateral to the plane of the
superfi cial aponeurotic system (SMAS) over the parotid
area, and along the deep layer of the deep temporal
fascia over the cranium. It is then refl ected anteriorly
(Fig. 101-33).
Dissection continues anterior to the EAC to identify
the main trunk of the facial nerve, as done during
parotidectomy (see Chapter 62). If the facial nerve does
not need to be mobilized, a cuff of soft tissue is left
around the facial nerve to minimize direct traction on
the nerve when the facial fl ap is retracted anteriorly. In
select cases, an inferior superfi cial parotidectomy (“tail
parotidectomy”) may enhance exposure of the retro-
mandibular area. Attention is then directed to the
neck to identify and obtain proximal control of the
common, internal, and external carotid arteries, as well
as the internal jugular vein. Cranial nerves X through
XII are identifi ed and preserved. The sternocleidomas-
toid and digastric muscles are transected at their inser-
tion into the mastoid bone. The stylohyoid and
stylopharyngeus muscles are transected and the styloid
process is removed. The ninth cranial nerve can usually
be identifi ed at this time as it crosses lateral to the
ICA.
Mastoidectomy and dissection of the vertical portion
of the facial nerve allow superior translocation of the
nerve to provide wider access to the ITF (Fig. 101-34).
It also permits access to the jugular bulb and lower
cranial nerves. Completion of the infratemporal skull
base approach, including a temporal craniotomy and
orbitozygomatic osteotomy, is performed as described
in the previous section. At this time, the anterior, supe-
rior, medial, and posterior boundaries of the ITF are
well exposed, and all major vessels are “controlled”
(Fig. 101-35). Extirpation of the tumor can now
proceed, including the involved soft tissue and bone.
Reconstruction of the defect is performed as discussed
previously.
Anterior Transfacial Approach
(Facial Translocation)
This approach is best used for lesions invading the ITF,
the masticator space, or the pterygomaxillary fossa and
for tumors of the nasopharynx extending into the
ITF10,11 (Fig. 101-36) (see Chapter 105). A bicoronal
incision with an ipsilateral preauricular extension is
performed and extended through the subcutaneous
tissue (see “Preauricular [Subtemporal] Approach”
earlier in this chapter). A Weber-Fergusson incision is
completed and extended down to the periosteum. A
Text continues on page 1014.

1010
Section 11
Cranial Base Surgery
B
A
B
C
Figure 101-24. A, Preoperative magnetic reso-
nance image demonstrating a large angiofi broma
extending from the nasopharynx to the left infra-
temporal skull base. B, This tumor was completely
excised by subtemporal craniectomy from a left
infratemporal skull base approach. A marking pen
has been inserted through the nasal cavity to show
the extent of the communication with the nasophar-
ynx. C, Excellent healing of the surgical site is noted
postoperatively with no cosmetic deformity. Moder-
ate trismus with mild deviation of the jaw is
present.
Figure 101-25. The entire temporalis muscle is available for oblitera-
tion of a defect in the orbit or infratemporal skull base. (Redrawn from
Sekhar LN, Janecka IP [eds]: Surgery of Cranial Base Tumors. New York,
Raven Press, 1993.)

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1011
B
C
A
Figure 101-26. A, The anterior portion
of the muscle may be transposed to fi ll an
infratemporal skull base defect, as illustrated
with this left temporalis muscle. B, The right
temporalis muscle has been split vertically
with preservation of its axial blood supply.
C, The posterior one half of the muscle is
sutured to the fascia or bone bordering the
superior temporal line and lateral orbital
rim to prevent a cosmetic defect.
Figure 101-27. This patient required orbital exenteration and
resection of the lateral orbital wall for recurrent squamous cell carci-
noma. The defect was reconstructed by temporalis muscle transposi-
tion and a skin graft.
Figure 101-28. Large soft tissue defects are best reconstructed by
microvascular free tissue transfer, most commonly the rectus abdomi-
nis muscle.
Figure 101-29. A curvilinear incision is made from the temporal
area to the mastoid bone and upper cervical region. The fl ap is ele-
vated superfi cial to the deep temporal fascia, deep to the mastoid
periosteum, and deep to the platysma muscle. A conchal incision is
preferable to incision of the external auditory canal when permanent
obliteration of the ear is not indicated.

1012
Section 11
Cranial Base Surgery
A
B
Figure 101-30. The conchal incision is made at the margins of the
conchal bowl to facilitate closure and provide an optimal cosmetic
result.
Figure 101-31. The auricle is repaired by double-layer closure of
the perichondrium and skin. A watertight closure is achieved to
prevent cerebrospinal fl uid otorrhea.
Figure 101-32. The conchal
incision communicates with the
postauricular incision (A), and a
Penrose drain is used to retract the
auricle and facial fl ap anteriorly
(B).

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1013
A
B
Figure 101-33. The facial fl ap is refl ected anteriorly with exposure
of the temporalis muscle, orbitozygomatic bone, masseteric fascia,
mandible, parotid gland and facial nerve, and cervical vessels and
nerves. The conchal tissues of the auricle are temporarily sewn
together to maximize operative exposure.
Figure 101-34. The facial nerve has been completely mobilized from
the parotid gland to the second genu. Mastoidectomy and resection of
the lateral temporal bone have been performed. A vessel loop is placed
around the internal carotid artery. The patient is in the right lateral
surgical position.
Figure 101-35. The extent of surgical exposure is demonstrated
after temporal craniotomy and refl ection of the temporalis muscle
inferiorly.
Figure 101-36. A and B, Com-
puted tomography scans demon-
strating
a
large
ameloblastic
fi brosarcoma of the left maxilla
with extension into the infratem-
poral fossa. The anterior transfa-
cial approach is ideally suited for
excision of such lesions.

1014
Section 11
Cranial Base Surgery
horizontal incision is carried over the superior edge of
the zygomatic bone and extended into the lateral
canthus to meet the Weber-Fergusson incision (Fig.
101-37). The frontal branches of the facial nerve are
identifi ed and dissected as they cross over the zygomatic
arch. They are then entubulated with silicone tubing
and transected. These nerve branches will be reanasto-
mosed at the end of the procedure with an entubula-
tion technique (Fig. 101-38). An inferiorly based fl ap
that includes the upper third of the upper lip, the
entire cheek, the lower eyelid, the parotid gland, and
the facial nerve is refl ected inferiorly. The infraorbital
nerve is transected and tagged to facilitate reanastomo-
sis at the end of the procedure. The frontotemporal
scalp fl ap is elevated in a subpericranial plane. This fl ap
is refl ected anteriorly to expose the superior orbital
rims (Fig. 101-39).
Orbitozygomatic osteotomies are performed and
joined with unilateral maxillary Le Fort II or Le Fort III
osteotomies to free the anterior face of the maxilla en
bloc with the orbitozygomatic complex. Alternatively,
this bone graft can be elevated as a vascularized graft
attached to the cheek fl ap, as described by Catalano
and Biller.8 The temporal and masseter muscles are
dissected from the zygomatic bone with electrocautery.
Osteotomies are completed, and the bone graft is
removed (Fig. 101-40). The temporalis muscle is
refl ected inferiorly. An osteotomy or removal of the
coronoid process increases the caudal arc of rotation of
the temporalis muscle. At this time, the anterior, medial,
and lateral boundaries of the ITF are well exposed (Fig.
101-41). In select cases, the pterygoid plates can be
excised to provide further access to the medial ITF or
nasopharynx. A temporal-subtemporal craniotomy pro-
vides additional exposure superiorly and allows dissec-
tion of intracranial structures (Fig. 101-42). After tumor
resection, the temporalis muscle may be transposed to
obliterate the surgical defect and provide separation of
the cranial cavity from the upper aerodigestive tract
(Fig. 101-43).
The incisions are closed in a multilayer technique.
The conjunctiva is repaired with running 6-0 mild
A
B
Figure 101-37. A and B, A hemicoronal incision is combined with
an extended Weber-Fergusson incision in the anterior transfacial
approach. The incision may be made through the conjunctiva or
through the skin several millimeters inferior to the ciliary line.
Figure 101-38. Multiple temporal branches of the facial nerve are
identifi ed and entubulated with silicone tubes before transection.
This facilitates anastomosis of the nerves at the end of the
procedure.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1015
Figure 101-39. The scalp and facial fl aps are elevated from the
underlying bone and muscle fascia to expose the facial skeleton.
The inferior orbital nerve is transected but tagged for later
reconstruction.
A
B
Figure 101-40. A, Segments of the facial skeleton that are removed en bloc with the anterior transfacial approach. B, Exposure provided by
this approach.
chromic suture. The lacrimal canaliculi are stented with
Crawford silicone tubing secured in the nasal cavity.
The eye is closed with a temporary tarsorrhaphy for 10
to 14 days to prevent lower lid ectropion.
Transorbital Approach
In select cases, a transorbital approach may be used for
optimal exposure of the orbital apex and cavernous
sinus. This approach consists of transection of the
orbital tissues posterior to the globe with preservation
of the attachments of the superfi cial orbital structures,
including the globe, to the scalp fl ap.
The tissues of the orbital apex and surrounding
bone are then removed to provide direct anterior access
to the cavernous sinus and cavernous ICA. This
approach is reserved for patients with benign tumors of
the orbital apex and cavernous sinus who have already
lost vision as a result of tumor growth (Fig. 101-44). It
may also be used for limited malignant neoplasms with
minimal involvement of the orbital tissues. More exten-
sive involvement of the orbital tissues requires orbital
exenteration. The advantages of this approach are an
improved cosmetic result with preservation of the globe
and excellent anterior and lateral exposure of the cav-
ernous sinus and its associated structures.
A preauricular infratemporal skull base approach is
used. After elevation of the scalp fl ap (Fig. 101-45), an
orbitozygomatic osteotomy is performed (Fig. 101-46).

1016
Section 11
Cranial Base Surgery
Figure 101-41. After transection of the coronoid process of the
mandible and refl ection of the temporalis muscle inferiorly, the infra-
temporal skull base, maxilla, and nasopharynx are well exposed.
Figure 101-42. A subtemporal craniectomy is performed to provide
additional exposure and an adequate resection margin of extracra-
nial tumors. Maximal exposure of the infratemporal and central skull
base is achieved.
A
B
Figure 101-43. The entire temporalis muscle (A) or the anterior one half of the muscle (B) may be transposed to obliterate the surgical
defect and provide separation of the cranial cavity from the upper aerodigestive tract. If the temporalis muscle is not available because of loss
of its blood supply, microvascular free fl ap reconstruction is indicated.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1017
A
B
Figure 101-44. Magnetic reso-
nance image (A) and computed
tomography scan (B) demonstrat-
ing a meningioma involving the
lateral wall of the orbit with exten-
sion to the orbital apex and middle
cranial fossa. If the patient has
permanent visual loss as a result
of such a tumor, a transorbital
approach may be used.
A
B
Figure 101-45. A cadaver dissection is used to demonstrate the
transorbital approach. A, A hemicoronal scalp incision with extension
to the preauricular area is made. B, The scalp fl ap is elevated deep
to the pericranium and superfi cial to the deep temporalis fascia. The
periorbita is elevated from the superior and lateral orbital walls, and
the temporalis muscle is elevated.
Figure 101-46. A frontotemporal craniotomy and orbitozygomatic
osteotomy are performed to provide direct lateral access to the orbital
tissues and cavernous sinus region.
The periorbita is elevated from the superior, lateral,
and inferior walls of the orbit. The periorbita is then
incised, and orbital tissues are transected posterior to
the globe with bipolar electrocautery and sharp dissec-
tion. A cuff of tissue remains at the orbital apex to
provide an adequate tumor margin. The remaining
periorbital attachments are then elevated medially to
allow complete displacement of the globe from the
orbital cavity (Fig. 101-47). Using rongeurs, bone is
removed from the lateral wall of the orbit to the superior
orbital fi ssure. The contents of the superior orbital
fi ssure and the optic canal are then transected to provide
additional exposure of the orbital apex (Fig. 101-48).
Further removal of bone and dissection of intracranial
structures are performed in conjunction with the
neurosurgeon.
Because of loss of orbital support, enophthalmos
results unless the orbital defect is reconstructed with
bone grafts or soft tissue is interposed. A temporalis
transposition or free tissue transfer provides excellent
soft tissue augmentation and protection of the carotid
artery.
Endoscopic Approaches
Select benign tumors originating at the ITF and select
benign and malignant tumors of the sinonasal tract
extending to the ITF are amenable to resection by

1018
Section 11
Cranial Base Surgery
endoscopic transnasal or transantral techniques (or
both).14-17
The patient’s head is usually fi xed in a three-pin
fi xation system to facilitate navigation with a line-of-
sight optical system. The nose is decongested with
0.05% oxymetazoline. Both sides of the nose are used
for the surgical corridor, which is augmented by resec-
tion of the posterior septum. Because a bimanual tech-
nique is necessary for surgical dissection in this area, a
two-surgeon, four-hands technique is recommended.
Access to the ITF is gained by removing the medial and
posterolateral walls of the antrum. Depending on the
need for further exposure, the pterygoid plates, the
torus tubarius, and the medial eustachian tube may be
removed. To increase lateral exposure, the piriform
aperture may also be removed to increase the angle of
exposure. The basic steps include removal of the middle
turbinate ipsilateral to the lesion; posterior septectomy;
creation of a wide middle nasoantral window (may be
extended inferiorly by removing the posterior one half
of the inferior turbinate); removal of the posterior and
lateral walls of the antrum; control of the neurovascular
structures of the pterygopalatine fossa by ligation of the
sphenopalatine and posterior nasal arteries; and, if nec-
essary, removal of the pterygoid plates, the torus tubar-
ius, and the middle one third of the eustachian tube.
POSTOPERATIVE MANAGEMENT
The patient is transferred to an intensive care unit for
continuous cardiovascular and neurologic monitoring.
Laboratory tests are ordered to rule out postoperative
anemia and electrolyte abnormalities. Patients requir-
ing multiple blood transfusions should be screened for
transfusion-induced coagulation disorders. Mild nar-
cotic analgesia is provided, but strong narcotic or seda-
tive medications are avoided to prevent interference
with accurate neurologic assessment.
If surgical manipulation, ligation, or grafting of the
ICA has been performed, close monitoring of the
patient’s hemodynamic status is essential. Blood trans-
fusions are considered when the hematocrit is less than
27% or the patient shows heart or brain disfunction.
Fluid balance is carefully monitored to prevent hypo-
tension. Strict bed rest is maintained for several days
until the patient is hemodynamically stable to prevent
hypotension. A CT scan of the head without contrast
enhancement is performed on the fi rst or second post-
operative day to screen for intracranial complications,
such as cerebral contusions, signifi cant edema, hemor-
rhage, fl uid collections, or pneumocephalus. When
grafting of the ICA is performed or after surgical injury,
an angiogram is obtained in the early postoperative
period to assess the patency of the graft and detect
pseudoaneurysm formation.
A compressive dressing is maintained for 24 to 72
hours. Once the dressing is removed, the wound is
cleaned with normal saline solution and covered with
antibiotic ointment three to four times a day. The scalp
and other wound drains are kept on suction (80 mm Hg)
until the amount of drainage is less than 20 mL/day. If
the cranial cavity is entered, suction drainage is not
used because of the risk of direct negative pressure on
the central nervous system, and the drains are left to
gravity drainage.
In most cases, the spinal drain is needed only during
surgery and is removed on completion of the proce-
dure. If there is a signifi cant risk of postoperative CSF
leak, the spinal drain is kept at the level of the patient’s
shoulder and 50 mL are removed every 8 to 12 hours.
The spinal drain is removed 3 to 5 days after surgery.
The lumbar puncture site is closed with an encircling
stitch (e.g., 2-0 nylon) placed at the time of surgery.
Inadequate closure of the eye because of weakness
or paralysis of the facial nerve may lead to exposure
keratoconjunctivitis. Initially, an exposed eye can be
protected with artifi cial tears every 1 to 2 hours, lubrica-
tion ointment at bedtime, eye patching, or a moisture
chamber. Taping or a temporary tarsorrhaphy is advised
if rapid recovery is anticipated. If prolonged paralysis is
expected, the authors prefer a gold weight implant.
Implantation of a 0.1- to 0.12-g weight (no. 10 or 12)
can be performed at the time of the original surgery,
or it may be performed days later. Except in select cases,
Figure 101-48. Additional bone is removed from the orbit and
infratemporal skull base to provide exposure of the contents of the
superior orbital fi ssure and cavernous sinus region.
Figure 101-47. The orbital tissues are transected posterior to the
globe.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1019
the authors favor the latter because it provides the
advantage of being able to insert the exact weight
needed by the patient.
In the vast majority of cases, the airway can be
secured with a short-term endotracheal tube (high-
volume/low-pressure cuff). Nevertheless, for patients in
whom signifi cant edema of the upper aerodigestive
tract or prolonged intubation is anticipated, the authors
recommend a tracheotomy. In patients with an ineffec-
tive cough or severe aspiration, tracheotomy also pro-
vides better access to the airway for pulmonary toilet.
Patients with high vagal lesions or any combination
of defi cits of cranial nerves IX, X, or XII will suffer
severe swallowing diffi culty and aspiration. These
patients can be assisted with a thyroplasty type I/aryte-
noid adduction procedure with or without cricopharyn-
geal myotomy. Patients who continue to aspirate are
managed with a laryngotracheal separation procedure
(see Chapter 69).
COMPLICATIONS
Most of the morbidity associated with conventional
cranial base surgery for neoplasms involving the ITF is
related to defi cits of the trigeminal nerve. Sacrifi ce of
the third and sometimes the second division of the tri-
geminal nerve may be necessary for surgical exposure
or adequate tumor margins. Facial anesthesia may pre-
dispose the patient to self-infl icted injuries. On rare
occasions, neurotrophic ulcers may develop as a result
of repeated self-infl icted trauma. Loss of corneal sensa-
tion, especially in someone with paresis of the facial
nerve, greatly increases the risk of corneal abrasion or
exposure keratitis. Loss of motor function of the man-
dibular nerve causes asymmetry of the jaw opening and
decreased force of mastication on that side (Fig.
101-49). Mastication may be further impaired by resec-
tion of the TMJ or mandibular ramus. Whenever feasi-
ble, the sensory and motor divisions of the trigeminal
nerve are repaired after transection for surgical
exposure.
Accidental injury to the facial nerve with subse-
quent permanent paralysis is uncommon, although pos-
sible with the approaches described here. The temporal
branches of the facial nerve are at risk for injury with
elevation of the scalp fl ap. Injury is usually a result of
dissection in a plane superfi cial to the superfi cial layer
of the deep temporal fascia. The main trunk of the
facial nerve is susceptible to traction injury with retrac-
tion of the facial fl ap anteriorly. For this reason, a
pedicle of soft tissue is preserved around the facial
nerve when a preauricular approach is used. Tempo-
rary paresis of the facial nerve is to be expected with
mobilization of the mastoid segment of the facial nerve.
Close attention to postoperative eye care must
be observed in patients with combined defi cits of the
trigeminal and facial nerves.
Postoperative trismus is a common occurrence
because of postoperative pain and scarring of the ptery-
goid musculature and TMJ (see Fig. 101-24C). Less
trismus is noted six months postoperatively if patients
regularly perform stretching exercises by opening the
jaw. Devices such as the Therabite appliance are helpful
in stretching the scar tissue and forcefully opening the
mouth. In severe cases, a dental appliance that is gradu-
ally opened with a screw may be fabricated. Surgical
resection of the TMJ does not appear to be a major
factor in the development of postoperative trismus or
diffi culties with mastication. Rather, mastication appears
to be most affected by loss of function of the mandibu-
lar division of the trigeminal nerve. Nevertheless, every
attempt is made to preserve the TMJ. If resection of the
glenoid fossa is necessary, the capsule of the TMJ is
displaced inferiorly. If resection of the TMJ is necessary,
no attempt is made to reconstruct the joint.
Infectious complications are rare. Predisposing
factors include communication with the nasopharynx,
seroma or hematoma, and a CSF leak. In general, all
dead spaces should be obliterated to prevent collection
of fl uid. The use of vascularized tissue fl aps is preferred,
especially when dissection of the ICA or resection of
dura has been carried out.
Necrosis of scalp fl aps is an uncommon occurrence
because of the excellent blood supply of the scalp.
Poorly designed incisions, however, may result in areas
of hypovascularity, particularly around the auricle (Fig.
101-50).
Vascular complications are a great concern with
surgery in this area. Surgical dissection of the ICA can
result in injury to the wall with either immediate or
delayed hemorrhage. The artery is particularly vulner-
able to injury at the point where it enters the cranial
base. Injuries to the ICA should be repaired primarily.
An angiogram is obtained in the early postoperative
period to assess adequacy of the repair and to detect
early pseudoaneurysm formation. In the event that
repair of the artery is not possible, permanent occlusion
of the artery by ligation or placement of a detachable
latex balloon or vascular coil may be performed. There
Figure 101-49. Mild malocclusion is noted in this patient after an
infratemporal skull base approach. A posterior open bite and devia-
tion of the mandible to the right side are noted.

1020
Section 11
Cranial Base Surgery
is a signifi cant risk of immediate and delayed stroke,
however, in patients who do not have greater than 35
to 40 mL of blood fl ow/min/100 g brain tissue by
ABOX-CT testing.
Postoperative cerebral ischemia may result from
surgical occlusion of the ICA, temporary vasospasm, and
thromboembolic phenomena. When the artery is per-
manently occluded, the occlusion is performed as distal
as possible near the origin of the ophthalmic artery. It is
believed that there is less potential for thrombus forma-
tion with a short column of stagnant blood above the
level of occlusion. After reconstruction of the ICA with
a vein graft, there is a risk of postoperative occlusion
secondary to thrombus formation at the suture line, as
well as torsion or kinking of the graft. Pseudoaneurysm
formation and delayed blowout of the graft are also
risks, especially in the presence of infection. For this
reason, reconstruction of the ICA is not usually per-
formed in a contaminated fi eld in which there is com-
munication with the upper aerodigestive tract. In such
cases, permanent occlusion of the ICA or rerouting of a
vein graft posterior to the surgical fi eld is performed. An
extracranial-intracranial bypass graft to the middle cere-
bral artery may be performed before tumor resection
when sacrifi ce of the ICA is anticipated. Patients who
undergo surgical manipulation of the ICA are also sus-
ceptible to cerebral ischemia in watershed areas, at the
margins of the vascular territories of the cerebral vessels.
This is of particular concern when extracranial-intracra-
nial collateral blood vessels, which are not routinely
assessed by ABOX-CT, have been sacrifi ced as part of
the surgical approach. Decreased oxygen delivery
because of postoperative anemia or hypotension can
result in cerebral infarction in these watershed areas.
Watertight dural closure may be diffi cult to achieve
with large infratemporal skull base defects, particularly
around nerves and vessels. An epidural fl uid collection
may result. In most cases, it is contained by the soft
tissues and slowly resolves without further intervention.
Occasionally, the CSF collection may communicate
with the outside through the EAC or along the eusta-
chian tube to the nasopharynx. Most CSF leaks can be
managed nonsurgically by placement of a spinal drain
to lower CSF pressure and an external pressure dress-
ing. If the CSF leak does not resolve within 1 week,
surgical exploration and repair of the dural defect may
be necessary. A middle ear effusion is often apparent
after infratemporal skull base approaches as a result of
dysfunction or interruption of the eustachian tube.
Tympanostomy tubes are not placed for at least 6 weeks
postoperatively because there is always a risk of CSF
communication. The authors have encountered a few
patients with profuse unilateral rhinorrhea in the post-
A
B
Figure 101-50. This patient had previously undergone surgery that
used a question mark–shaped left temporal incision. A, There is an
additional scar anterior to the auricle. These incisions are cosmeti-
cally unfavorable, may violate the underlying temporalis muscle, and
greatly increase the risk of injury to the temporal branches of the
facial nerve. B, It was necessary to use segments of the original scars
on reoperation to prevent further compromise of the vascularity of
the scalp and auricle.
A
B
Figure 101-51. A, Computed tomography scan demonstrating
hemangiopericytoma of the right temporal area with involvement of
the temporalis muscle, orbitozygomatic bone, and orbit. B, Resection
of the temporalis muscle, lateral orbital wall, zygomatic bone, and
orbit was necessary to achieve clear tumor resection margins but
resulted in a signifi cant cosmetic deformity.

Chapter 101
Surgical Approaches to the Infratemporal Fossa 1021
operative period that was misinterpreted as a CSF leak.
These cases were all associated with surgical manipula-
tion of the ICA and were probably due to loss of sym-
pathetic fi bers to the nasal mucosa that travel along the
ICA. This represents a form of iatrogenic vasomotor
rhinitis and may be treated similarly with the use of
anticholinergic nasal sprays. Testing of the fl uid for β2-
transferrin may be necessary to rule out a CSF leak.
Cosmetic deformities may result from the loss of
soft tissue and bone (Fig. 101-51). Transposition of the
temporalis muscle results in a depression in the tempo-
ral area (Fig. 101-52). It can be lessened by placement
of a free fat graft at the time of surgery or at a later date.
If the temporalis muscle is not transposed, the anterior
margin of the muscle should be resutured anteriorly to
prevent a slight depression lateral to the orbital rim.
The use of free muscle fl aps for reconstruction may
necessitate sacrifi ce of the zygomatic arch. With atrophy
of the muscle, a signifi cant depression may occur. Large
lateral muscle fl aps, such as a latissimus dorsi fl ap, may
also compress the brain if the underlying cranium is not
reconstructed.
Figure 101-52. This 8-year-old boy underwent a left infratemporal
skull base approach for excision of a large angiofi broma that involved
the infratemporal skull base. The infratemporal skull base was recon-
structed via temporalis muscle transposition, and a signifi cant depres-
sion was left in the temporal area. This depression was later
reconstructed with a custom-made alloplastic implant.
References
1. Fairbanks-Barbosa J: Surgery of extensive cancer of paranasal
sinuses. Presentation of a new technique. Arch Otolaryngol
73:129-138, 1961.
2. Terz JJ, Young HF, Lawrence W Jr: Combined craniofacial resec-
tion for locally advanced carcinoma of the head and neck. II.
Carcinoma of the paranasal sinuses. Am J Surg 140:618-624,
1980.
3. Fisch U: The infratemporal fossa approach for the lateral skull
base. Otolaryngol Clin North Am 17:513-552, 1984.
4. Biller HF, Shugar JMA, Krespi YP: A new technique for wide-fi eld
exposure of the base of the skull. Arch Otolaryngol 107:698-707,
1981.
5. Sekhar LN, Schramm VL, Jones NF: Subtemporal-preauricular
infratemporal fossa approach to large lateral and posterior
cranial base neoplasms. J Neurosurg 67:488-499, 1987.
6. Cocke EW Jr, Robertson JH, Robertson JT, Crooke JP Jr: The
extended maxillotomy and subtotal maxillectomy for excision of
skull base tumors. Arch Otolaryngol Head Neck Surg 116:92-104,
1990.
7. Janecka IP, Sen CN, Sekhar LN, Arriaga M: Facial translocation:
A new approach to the cranial base. Otolaryngol Head Neck Surg
103:413-419, 1990.
8. Catalano PJ, Biller HF: Extended osteoplastic maxillotomy. A
versatile new procedure for wide access to the central skull base
and infratemporal fossa. Arch Otolaryngol Head Neck Surg
119:394-400, 1993.
9. Snyderman CH, D’Amico F: Outcome of carotid artery resection
for neoplastic disease: A meta-analysis. Am J Otolaryngol 13:373-
380, 1992.
10. Johnson JT, Derkay CS, Mandell-Brown MK, Newman RK (eds):
AAO-HNS Instructional Courses, vol 6. New York, Mosby-Year
Book, 1993, pp 341-346.
11. Nuss DW, Janecka IP, Sekhar LN, Sen CN: Craniofacial disas-
sembly in the management of skull-base tumors. Otolaryngol Clin
North Am 24:1465-1497, 1991.
PEARLS
• Establishment of the origin and extension of tumors
involving the ITF is critical to provide optimal
surgical management.
• Subtle lower cranial nerve symptoms are often the
fi rst sign of ITF/skull base pathology.
• Postoperative stretching and physical therapy will
facilitate improved TMJ range of motion and reduce
the extent of trismus at 6 months.
• Because of wide variability in histopathology of the
ITF, preoperative pathologic confi rmation is
necessary before proceeding to major ablative
surgery.
• Large soft tissue and bone defects are best
reconstructed with composite free tissue transfer.
• Partial resuspension of the temporalis muscle to the
lateral orbital rim will minimize cosmetic deformity
postoperatively.
PITFALLS
• Despite preoperative carotid balloon test occlusion
with CT xenon fl ow testing, some patients will still
suffer ischemic brain injury because of loss of
collateral vessels and nonphysiologic conditions
during testing.
• Dissection superfi cial to the superfi cial layer of the
deep temporal fascia will put the frontal branch of
the facial nerve at risk.
• After resection of the condyle, reconstruction of the
TMJ may lead to more scarring and trismus than
would occur with no reconstruction.
• Large composite defects of bone and soft tissue are
best reconstructed with a free tissue transfer that
includes bone to minimize postoperative cosmetic
morbidity.
• Unilateral rhinorrhea may be misinterpreted as a
CSF leak when in fact it is related to manipulation
of the sympathetic supply to the nose during carotid
artery dissection.
• Patients with lower cranial nerve defi cits will have
signifi cant impairment of speech and swallowing
function that will necessitate aggressive
rehabilitation, if not surgical correction and
augmentation.

1022
Section 11
Cranial Base Surgery
12. Sekhar LN, Sen C, Snyderman CH, Janecka IP: Anterior, antero-
lateral, and lateral approaches to extradural petroclival tumors.
In Sekhar LN, Janecka IP (eds): Surgery of Cranial Base Tumors.
New York, Raven Press, 1993, pp 157-223.
13. Mansour OI, Carrau RL, Snyderman CH, Kassam AB: Preauricu-
lar infratemporal fossa surgical approach: Technique and surgi-
cal indications. Skull Base 14:143-151, 2004.
14. Bilsky MH, Bentz B, Vitaz T, et al: Craniofacial resection for
cranial base malignancies involving the infratemporal fossa. Neu-
rosurgery 57(4 Suppl):339-347, 2005.
15. Kassam AB, Gardner P, Snyderman C, et al: Expanded endonasal
approach: Fully endoscopic, completely transnasal approach to
the middle third of the clivus, petrous bone, middle cranial fossa,
and infratemporal fossa. Neurosurg Focus 19(1):E6, 2005.
16. Robinson S, Patel N, Wormald PJ: Endoscopic management of
benign tumors extending into the infratemporal fossa: A two-
surgeon transnasal approach. Laryngoscope 115:1818-1822,
2005.
17. Hartnick CJ. Myseros JS, Myer CM 3rd: Endoscopic access to the
infratemporal fossa and skull base: A cadaveric study. Arch Oto-
laryngol Head Neck Surg 127:1325-1327, 2001.

Chapter 102
Petrosal Approaches
Trevor Hackman and Elizabeth H. Toh
Several surgical approaches can be used to provide
access to the petrous apex and lateral skull base for
resection of tumors within the middle and posterior
cranial fossae. The most common tumors of the skull
base include petroclival meningiomas, chordomas, and
chondrosarcomas. The most common lesions in the
petrous apex include mucoceles, epidermoids, choles-
terol granulomas, and arachnoid cysts. Petroclival
meningiomas are the predominant lesions requiring
petrosal approaches for surgical resection.
Multiple surgical approaches have been developed
over the years to provide access to tumors in the petro-
clival region. Central to all these approaches is the
ability to develop exposure through which the tumor
can be visualized and spare important neural and vas-
cular structures within the petroclival region. In the
past, morbidity and mortality rates in patients treated
surgically for petroclival tumors was high, probably
because of lack of knowledge of petrous temporal bone
anatomy and therefore a tendency to attempt surgical
approaches through the more familiar suboccipital
and pterional approaches. Transpetrosal approaches
through the lateral skull base offer more direct surgical
exposure for resection of tumors in the petroclival
region and less risk to neurovascular structures lateral
and anterior to the brain stem.
Current transpetrosal approaches encompass a
variety of surgical exposures through the petrous
portion of the temporal bone to provide access to the
cerebellopontine angle, the petroclival region, the
basilar artery, and the brain stem (Table 102-1). Abdel
Aziz and colleagues in 2000 grouped transpetrosal
approaches into anterior and posterior categories and
then subclassifi ed them into individual approaches
based on the spectrum of bone resection and exposure
of the posterior fossa.1 The anterior transpetrosal
approaches to the posterior fossa, also known as sub-
temporal approaches, are a continuum of the basic
middle fossa approach. The addition of anterior petro-
sectomy and opening of the temporal lobe dura mater
enhances visualization of the posterior fossa. The pos-
terior transpetrosal approaches include the retrolaby-
rinthine, translabyrinthine, transcochlear, and total
petrosectomy approaches, use of which depends on the
location and extent of the tumor.
The location and extent of cranial base tumors
within the middle and posterior fossae often necessitate
a combination of petrosal approaches, such as a sub-
temporal middle fossa approach along with a transpe-
trosal approach, to enhance surgical exposure and
thereby limit neurovascular morbidity. The extent of
temporal bone resection required for adequate expo-
sure is dependent on the approach and tumor location.
Anterior, posterior, combined, and complete petrous
bone resections must be tailored to each case.
Advantages of transpetrosal approaches include (1)
minimal retraction of the cerebellum and temporal
lobe; (2) reduced operative distance of the clivus (3 cm
shorter than with the suboccipital approach); (3) supe-
rior angle of surgical exposure with regard to the ante-
rior and lateral aspects of the brain stem; (4) preservation
of the vein of Labbé and the transverse and sigmoid
sinuses; (5) anatomic preservation of all critical neural
and otologic structures, including the cochlea, vesti-
bule, and facial nerve; (6) availability of multiple angles
and routes for tumor resection within the same surgical
exposure; and (7) early vascular control of the tumor,
thus making subsequent tumor resection easier.2-4
The development of newer microsurgical and skull
base surgery techniques, along with improvements in
anesthesia, neuroradiology, and monitoring, have sig-
nifi cantly reduced surgical morbidity. Recently, newer
techniques, including stereotactic radiation therapy
and surgical resection through expanded endoscopic
nasal approaches, have been used to treat these lesions
with relatively low complication rates. Stereotactic radi-
ation therapy offers a nonsurgical option for control-
ling tumor growth. The expanded endoscopic nasal
1023

1024
Section 11
Cranial Base Surgery
approach is used for removal of lesions in the middle
third of the clivus, petrous internal carotid artery, cav-
ernous sinus, and medial infratemporal fossa, which are
located centrally with the surrounding neurovascular
structures displaced laterally.5
PATIENT SELECTION
Factors found to be important in determining selection
of the approach for surgery include the size, location,
and extent of the tumor; anatomic variations in tempo-
ral bone anatomy; location of the sigmoid sinus; and
the patient’s hearing status. Larger tumors and those
with involvement of critical neurovascular structures
are more likely to require a combination of approaches
for optimal surgical exposure. The approach selected
should be tailored to fi t the individual patient and maxi-
mize access while limiting morbidity. Abdel Aziz and
colleagues developed a zoning classifi cation for lateral
skull base lesions to guide selection of the surgical
approach (Fig. 102-1). Zone I (upper zone) extends
from the dorsum sellae to the upper border of the
internal auditory canal (IAC) and represents the expo-
sure provided via the anterior petrosal approaches.
Zone II (middle zone) extends from the IAC to the
upper border of the jugular tubercle and represents the
exposure provided via the posterior petrosal approaches.
Zone III (lower zone) extends from the upper border
of the jugular tubercle to the lower edge of the clivus
and represents the exposure provided via a transcondy-
lar approach. Zone III is essentially the anterior lip of
the foramen magnum.1
Anterior Petrosal Approaches
Based on the standard middle fossa approach, anterior
petrosal approaches can provide exposure for resection
of zone I lesions extending from the oculomotor nerve
anterosuperiorly down to the IAC posteroinferiorly.
They also provide the advantage of optimal exposure
and vascular control of the petrous carotid artery and
superior visualization of the upper clivus. Their relative
disadvantages include the risk of facial nerve injury,
necessity for temporal lobe retraction, and limited
access to the posterior fossa.
Middle Fossa Approach to the Internal
Auditory Canal
Indications for the use of this approach and the surgical
technique are described in detail in Chapter 124.
Middle Fossa Approach to the Petrous
Carotid Artery
Anatomic identifi cation of the petrous carotid artery is
paramount for successful surgical outcomes in skull
base surgery, especially when intraoperative hemor-
rhage is anticipated or when the tumor directly involves
the carotid artery or cavernous sinus (or both). Tumors
with extensive invasion of the temporal bone, such as
squamous cell carcinoma, paraganglioma, and high-
grade chondrosarcoma, or tumors of the cranial base,
such as meningioma, chondrosarcoma, and chordoma,
present such an extirpative dilemma. The middle fossa
approach was initially popularized by William House for
surgical removal of small acoustic neuromas in patients
with aidable hearing in the affected ear. It was subse-
quently adapted by Glasscock for exposure of the
petrous carotid artery and used for surgical removal of
skull base tumors in 1975 by Bochenek and Kukwa, who
termed the approach the anterior petrosal approach.2-4
The approach provides ideal surgical exposure of the
horizontal segment, vertical segment, and genu of the
petrous carotid artery, as well as for resection of petro-
clival lesions. With tumors involving the carotid artery,
the carotid artery may be mobilized and controlled
proximally and distally with this approach to allow
improved exposure, more controlled surgical resection,
and the ability to repair the carotid artery or perform
carotid artery bypass when indicated. Preoperative
assessment of these tumors with computed tomography
(CT), magnetic resonance imaging (MRI), angiogra-
Table 102-1
PETROSAL APPROACHES TO THE
CRANIAL BASE
Anterior petrosal approaches (middle fossa)
Classic subtemporal approach
Middle fossa approach to the internal auditory canal
Middle fossa approach to the petrous carotid artery
Petrous apicectomy
Posterior petrosal approaches
Retrolabyrinthine approach
Partial labyrinthine approach
Translabyrinthine approach
Transcochlear approach
Total petrosectomy
Combined anterior and posterior transpetrosal
approaches
Expanded endoscopic nasal approaches
I
II
III
Figure 102-1. Zoning classifi cation of lateral skull base lesions used
to select the surgical approach for resection.

Chapter 102
Petrosal Approaches 1025
phy, and balloon occlusion testing is essential for pre-
operative planning.
Petrous Apicectomy
Depending on the size, location, and neurovascular
involvement of the tumor, the standard middle fossa
approach may need to be expanded to include a petrous
apicectomy. When used alone, this approach affords
access to the midclivus, anterior cerebellopontine angle,
Meckel’s cave, the lateral wall of the cavernous sinus,
and the petroclival synchondrosis for resection of small
meningiomas, chondrosarcomas, and chordomas. The
petrous apicectomy approach can also be used to
manage aneurysms of the vertebrobasilar junction. The
expanded surgical fi eld also allows better vascular
control of larger petroclival tumors, thereby leading to
more complete and safer resection.
The increased labor associated with more extensive
bony resection of the petrous temporal bone in this
approach is well balanced by the improved surgical
vector and fi eld of exposure afforded to the clivus and
even the ventral portion of the posterior fossa. This
reduces the need for temporal lobe retraction, thus
minimizing the risk for neurologic sequelae caused by
prolonged temporal lobe retraction, such as seizures
and cerebrovascular events. For larger petroclival
tumors extending far into the posterior fossa, additional
exposure via a posterior petrosal approach is often
needed. In such cases, the anterior and posterior petro-
sal approaches are used in combination.
Posterior Petrosal (Transpetrosal)
Approaches
Posterior petrosal approaches include the retrolabyrin-
thine, partial labyrinthine, translabyrinthine, trans-
cochlear, and total petrosectomy approaches, for which
a mastoidectomy is the surgical foundation. The pro-
gressive degrees of bone resection anteriorly via the
retrolabyrinthine, translabyrinthine, and transcochlear
approaches, respectively, provide graduated exposure
of the posterior fossa within zone II (IAC to the jugular
tubercle).1 The retrolabyrinthine, translabyrinthine,
and transcochlear approaches, when combined with
temporal craniotomy and release of the tentorium, are
best suited for mid and upper petroclival lesions located
in the lateral, anterolateral, and anterior portions of the
brain stem, respectively.
Retrolabyrinthine Approach
The retrolabyrinthine approach is ideally suited for
patients with good hearing and medium to large tumors
of the midclivus and anterior cerebellopontine angle.
The approach may be combined with a middle fossa
approach for removal of larger lesions lateral to the
brain stem and over the clivus, with preservation of
hearing and facial nerve function and minimal morbid-
ity. The retrolabyrinthine approach hinges on the
ability to mobilize the sigmoid sinus posteriorly for
access to the posterior fossa through the presigmoid
space. Although the approach can provide lateral expo-
sure from cranial nerve IV to the upper border of the
jugular tubercle, the vestibular labyrinth anteriorly
limits access to the ventral (anterior) surface of the
brain stem and clivus, also known as the paramedian
portion of zone II (or the central clival depression).1,6
Therefore, tumors with dural attachment in the central
clival depression cannot be totally resected with this
approach.
The retrolabyrinthine approach is also limited by
the variable anatomy of the temporal bone. A con-
tracted mastoid or a far-forward sigmoid sinus can limit
the anteroposterior extent of bony exposure provided
through this approach. Similarly, a high-riding jugular
bulb or low-lying tegmen mastoideum can reduce the
superoinferior limits of surgical exposure. Tumor
involvement of the cavernous sinus or lower clivus often
necessitates additional exposure via a frontotemporal
orbital–zygomatic approach or transcondylar approach,
respectively. Alternatively, exposure of tumors in the
central clival depression may be accomplished via the
translabyrinthine or transcochlear approach with pos-
terior mobilization of the facial nerve and sacrifi ce of
hearing in that ear.1,6
Partial Labyrinthectomy Approach
The partial labyrinthectomy approach is an extension
of the retrolabyrinthine approach that provides addi-
tional ventral exposure while preserving hearing in the
operated ear. The principle of the partial labyrinthec-
tomy approach involves removal of only a portion of the
vestibular labyrinth, thereby attempting to conserve
hearing. Specifi cally, removal of the posterior and supe-
rior semicircular canals can provide an additional 6 to
10 mm of posterior exposure and 10 to 15 mm of supe-
rior exposure, which signifi cantly reduces temporal
lobe retraction and increases the angle of exposure up
to 30 degrees. The anterior limit of resection is the IAC.
Tumors extending only to the medial half of the IAC
can be removed through this exposure. Tumors extend-
ing into the lateral portion of the IAC require a trans-
labyrinthine approach if there is no useful hearing or
an anterior petrosal approach if hearing preservation is
being attempted. The partial labyrinthectomy approach
is typically reserved for large neoplastic and vascular
lesions in the midportion of the clivus between the tri-
geminal and vagus nerves.2
Translabyrinthine Approach
Patients with poor hearing or those with lesions extend-
ing into the IAC are considered suitable candidates for
the translabyrinthine approach. Removal of the vestibu-
lar labyrinth provides added exposure to the anterolat-
eral aspect of the clivus and brain stem but sacrifi ces
any residual hearing. The anterior limit of the approach
is the facial nerve, which is not mobilized with this
approach.
Transcochlear Approach
When additional access to the ventral aspect of the
clivus and brain stem is required and hearing is poor,
the translabyrinthine exposure can be extended into a

1026
Section 11
Cranial Base Surgery
transcochlear exposure by continuing the bony dissec-
tion anteriorly and drilling out the cochlea. The
approach provides superior lateral exposure and ventral
access to the brain stem, which aids in resection of
tumors in the central clival depression. The surgical
approach requires posterior mobilization of the facial
nerve with resultant facial dysfunction. Therefore, this
approach is used primarily for tumors involving the
petrous temporal bone, for large petroclival tumors
extending to the lateral clivus, for patients with preex-
isting facial nerve dysfunction, and for those with no
serviceable hearing.
Total Petrosectomy
Total petrosectomy provides the widest and most com-
plete fi eld of exposure for the petroclival region. The
approach involves extending the transcochlear approach
to include exposure and anterior mobilization of the
petrous carotid artery. This approach allows complete
resection of the petrous temporal bone and clivus when
these bones are involved with tumor, as well as removal
of giant petroclival tumors with signifi cant involvement
of the carotid artery. Total petrosectomy also gives the
widest possible access to the mid and upper clivus and
the entire zone II.1-6 Disadvantages of this approach
include extended operative time, complete hearing loss
in the operated ear, and signifi cant risk of injury to the
facial nerve and internal carotid artery. This approach
does not provide adequate exposure of zone III and the
lower clivus. Small lesions located in these areas may be
resected through a retrosigmoid approach, whereas
larger lesions will require a transcondylar approach.
Upper clival lesions resected through this approach
may require retraction of the temporal lobe or partial
resection of the inferior gyrus.
Expanded Endoscopic Nasal Approach
Recently, the expanded endoscopic nasal (endonasal)
approach has been proposed for removal of centrally
based lesions in the middle third of the clivus, petrous
internal carotid artery, and cavernous sinus when the
neurovascular structures are displaced laterally.5 The
principle of endonasal approaches to the skull base
centers around the anatomy of the sphenoid sinus,
which provides the gateway to the middle and posterior
cranial fossae. Also known as the transsphenoidal
approach, the expanded endonasal approach has many
advantages over lateral approaches, including improved
access and reduced morbidity. Traditional microscopic
transsphenoidal surgery was limited by the conical
exposure to the skull base and therefore a narrow
working fi eld. The advent of endoscopes has revolution-
ized this approach. Endoscopes provide magnifi ed
and unparalleled visualization of key structures,
thereby allowing better preservation of uninvolved
structures.7
When compared with lateral approaches and micro-
scopic approaches, endoscopic approaches provide
superior lighting, the ability to see around corners with
angled rigid telescopes, excellent maneuverability, and
a magnifi ed, comprehensive view of the surgical fi eld.4,7
The endoscopic approach also affords expanded visu-
alization in both the transverse and vertical dimensions
from the sella turcica to the foramen magnum. The
addition of three-dimensional image guidance technol-
ogy has allowed surgeons to extend approaches into the
middle and posterior skull base for resection of tumors
previously only approachable via traditional petrosal
approaches. From a cosmetic perspective, endonasal
approaches have a signifi cantly reduced burden of
healing and provide superior cosmesis by eliminating
external incisions and soft tissue retraction. From a
morbidity standpoint, the endonasal approach avoids
complications related to temporal lobe retraction and
injury to neurovascular structures typically encountered
with lateral approaches, thus decreasing the rate of
postoperative lower cranial neuropathy. Finally, the
reduced surgical morbidity allows patients with advanced
tumors to proceed with adjuvant radiation therapy in
timely manner.5,7
Endoscopic approaches come with some inherent
disadvantages. First and foremost, expanded endonasal
approaches require advanced endoscopic surgical skills,
which take signifi cant time to acquire. Second, because
of the relative infancy of expanded endonasal
approaches, only a few centers are using them. Third,
the endonasal approach does not usually permit en
bloc resection of the tumor. For the most commonly
encountered skull base neoplasms, this is not likely to
affect the long-term prognosis, especially if surgical
decompression is the primary goal of treatment. Con-
versely, the magnifi ed endoscopic view often provides
an enhanced view of tumor margins and attachment of
tumor to surrounding normal tissue. If complete tumor
resection is the treatment goal, additional tissue margins
may be sent for pathologic examination after the tumor
has been resected. Fourth, the incidence of cerebrospi-
nal fl uid (CSF) leakage is increased, and it may at times
be diffi cult to control endonasally. Finally, control of
bleeding during surgery requires considerable techni-
cal expertise and careful planning.5,7
PREOPERATIVE PLANNING
Preoperative evaluation of patients with petroclival
lesions includes an extensive history and physical exam-
ination. The history should focus on the onset and
duration of symptoms, including visual disturbances,
auditory changes, weakness, paresthesias, and voice and
swallowing abnormalities. Patients should have a com-
plete head and neck and neurologic examination,
including gait testing, cranial nerve examination, oto-
logic evaluation, and sensory and motor testing of
the extremities. Ancillary preoperative testing should
include a complete audiogram and imaging studies of
the skull base. Contrast-enhanced CT of the skull base,
including the temporal bone, and gadolinium-enhanced
MRI of the brain are essential for determining the
extent and location of the lesion and for selecting the
appropriate surgical approach or combination of
approaches. If symptoms of swallowing dysfunction are

Chapter 102
Petrosal Approaches 1027
detected preoperatively, videofl uoroscopic evaluation
of swallowing function should be performed. Preopera-
tive cranial nerve function should be carefully docu-
mented because the risk for postoperative cranial
neuropathy is signifi cant. Patients should be counseled
regarding the risk for potential postoperative cranial
neuropathy, temporal lobe injury, seizures, CSF leakage,
bleeding, and the possible need for additional surgery
to address these complications.
SURGICAL APPROACHES
Anterior Petrosal Approaches
Middle Fossa Approach to the Petrous
Carotid Artery
The patient is positioned supine with the head turned
so that the operated ear is facing up. The ipsilateral
shoulder is elevated to decrease tension on the cervical
musculature, stretching of the brachial plexus, and
torsion of the jugular veins. Intraoperative facial nerve
monitoring is established at the beginning of the pro-
cedure. Paralytic agents are not used after induction of
general anesthesia. Brain stem auditory evoked
responses are also monitored routinely because hearing
preservation is desired. Perioperative medications
administered include broad-spectrum antibiotics with
good CSF penetration (Ceftriaxone, 2 g); furosemide
(Lasix, 20 mg); mannitol, 0.5 mg/kg; and dexametha-
sone, 10 mg. Bacitracin (50,000 U/L of saline solution)
is used in the irrigation fl uid. Lumbar drainage is not
routinely performed.
When the goal of surgery is complete removal of a
petroclival lesion or isolation of the petrous carotid
artery, the standard skin incision used for the conven-
tional middle fossa approach (Fig. 102-2) must be
adapted to provide increased anterior and inferior
exposure (Fig. 102-3). The incision can be combined
with a modifi ed Blair incision to allow complete expo-
sure of the petrous carotid artery. The planned incision
is marked and then infi ltrated with a solution of 1%
lidocaine with 1 : 100,000 epinephrine 10 to 15 minutes
before elevation of the skin fl aps to provide hemostasis.
The incision is typically carried down through epider-
mis and dermis with a scalpel and then continued
through subcutaneous tissue with electrocautery. As the
skin fl ap is developed anteriorly, care should be taken
to avoid injury to the frontal branch of the facial nerve,
which courses over the zygomatic arch in a superfi cial
plane of loose areolar tissue anterior to the temporal
hairline. Knowledge of the scalp layers in this region is
essential to avoid injury to the facial nerve. The course
of the frontal branch of the facial nerve and layers of
the scalp are shown in Figures 102-4 and 102-5,
respectively.
The temporoparietal fascia, considered a contin-
uum of the superfi cial muscular aponeurosis of the
midface, fuses with the superfi cial layer of the deep
temporal fascia approximately 1 cm above the zygoma.
The facial nerve, which starts deep to the temporopari-
etal fascia in the midface, pierces through this fused
Figure 102-2. Standard skin incision used for the middle fossa
approach to the internal auditory canal.
Figure 102-3. Modifi cation of the temporal incision used for expo-
sure of a petrous carotid artery or for petrous apicectomy.

1028
Section 11
Cranial Base Surgery
Bone
Pericranium
Deep temporal artery
Temporalis muscle
Middle temporal artery
Temporalis fascia
Loose areolar tissue
Superficial temporal artery
Temporoparietal fascia
Subcutaneous tissue
Skin
Figure 102-4. Anatomy of the frontal branch of the facial nerve.
Figure 102-5. Layers of the scalp.
Figure 102-6. Dissection of the superfi cial layer of the deep tem-
poral fascia to preserve the frontal branch of the facial nerve.
fascial layer 1 cm above the zygoma and runs superfi cial
to the superfi cial temporal fascia until its termination
on the medial surface of the frontalis muscle. To protect
the facial nerve during anterior elevation of the skin
fl ap, the dissection should be performed deep to the
superfi cial layer of the temporal fascia. At the level of
the superior brow line, 2 cm above the zygomatic arch,
the deep temporal fascia splits into a deep layer and
superfi cial layer to envelop the zygomatic arch, between
which the superfi cial temporal fat pad can be found. At
this level the superfi cial temporal fascia is typically
incised (Fig. 102-6), and dissection is extended deep to
the superfi cial temporal fat pad, anteriorly and inferi-
orly along the surface of the deep temporal fascia to the
zygoma, to preserve the facial nerve in the skin fl ap
(Fig. 102-7).
The zygomatic arch, with or without the roof of the
glenoid fossa, is then removed via surgical osteotomies
to allow elevation of the remaining temporalis muscle
inferiorly out of the fi eld of dissection. This lowers the
level of the craniotomy to the fl oor of the middle fossa
and provides an improved angle of exposure under the
temporal lobe with less retraction of the temporal lobe.
The junction of the zygomatic arch and malar emi-
nence is divided via a chevron-shaped osteotomy with
an oscillating saw (Fig. 102-8). The glenoid fossa oste-
otomies are then performed medial to the glenoid fossa
to allow removal of the zygomatic arch over the roof of
the glenoid fossa.
An inferiorly based temporalis muscle fl ap is
then created by incising the muscle along the linea
temporalis while taking care to leave a superior cuff
of muscle attached to its insertion to facilitate subse-
quent muscle reapproximation. Dissection of the
temporalis muscle is carried as inferiorly as possible
to permit a low subtemporal approach and placement

Chapter 102
Petrosal Approaches 1029
A low temporal craniotomy is then performed with
a cutting burr or craniotome along the fl oor of the
middle fossa from the external auditory canal to
the orbital wall, which is possible only after removal of
the zygomatic arch. The superior aspect of the craniot-
omy often extends posterior to the external auditory
canal, and burr holes are often made for drilling access
when the craniotome is used (Fig. 102-10). Using a
dural elevator, the bone fl ap is carefully elevated off the
dura and soaked in saline until completion of the pro-
cedure. The completed craniotomy is shown in Figure
102-11. Next, a cutting burr or rongeur is used to lower
Figure 102-7. The frontal branch of the facial nerve is preserved
within the anterior skin fl ap.
Figure 102-8. Osteotomies used for removal of the zygomatic arch
and medial aspect of the glenoid fossa.
of self-retaining retractors or stay sutures. In this manner
the lateral surface of the skull is exposed (Fig. 102-9).
Posteriorly, the root of the zygoma, the glenoid fossa,
and the external auditory canal are identifi ed. Anterior
dissection has exposed the confl uence of the frontal,
sphenoidal, and temporal bones in an area known as
the pterion. Superiorly, the temporalis muscle has been
released from its insertion. The malar eminence and
the lateral and superior orbital rim are also exposed.
Insertion of
temporalis muscle
Pterion
Malar
eminence
Root of zygoma
Figure 102-9. Surface anatomy of the lateral skull base.
Figure 102-10. Location of the temporal craniotomy and removal
of the zygomatic arch.

1030
Section 11
Cranial Base Surgery
the inferior border of the craniotomy to the level of the
fl oor of the middle fossa.
The temporal lobe is then elevated extradurally
from the fl oor of the middle fossa in a posterior-to-
anterior direction. Familiarity with the surface anatomy
of the fl oor of the middle fossa is essential (Fig. 102-12).
The arcuate eminence, a round elevation of bone over-
lying the superior semicircular canal (the arcuate emi-
nence may be absent in 15% of patients8), is fi rst
identifi ed posteriorly. The sulcus of the superior petro-
sal sinus forms the medial boundary of the fl oor of the
middle fossa and dural exposure for this approach.
Knowledge of the relative locations of the vestibular
labyrinth, cochlea, facial nerve, and internal and exter-
nal auditory canal within the temporal bone is essential
for safe bony dissection (Fig. 102-13). As dural elevation
is continued anteriorly, the greater superfi cial petrosal
nerve (GSPN) is identifi ed coursing within the spheno-
petrosal groove. Posteriorly, the sphenopetrosal groove
forms the facial hiatus where the GSPN exits from the
geniculate ganglion. This portion of the facial nerve is
dehiscent in up to 15% of normal individuals, so gentle
dissection and minimal traction on the overlying dura
will avoid trauma to the facial nerve. The fi rst landmark
in the area overlying the horizontal segment of the
petrous carotid artery is the middle meningeal artery as
it emerges from the foramen spinosum anterior and
medial to the petrosquamous suture (Fig. 102-14). After
cauterizing and transecting this artery (Fig. 102-15), the
lesser superfi cial petrosal nerve, foramen ovale, and
Figure 102-11. Completed craniotomy for petrous carotid dissec-
tion and petrous apicectomy.
IAC
Arcuate eminence
GSPN
60°
60°
Facial nerve
Figure 102-12. Surface anatomy of the middle cranial fossa. GSPN,
greater superfi cial petrosal nerve; IAC, internal auditory canal.
Internal
auditory canal
Superior semicircular canal
(arcuate eminence)
Superior petrosal sinus
Petrosquamous
suture line
External
auditory canal
Carotid
artery
V3 division
foramen ovale
Trigeminal
ganglion
GSPN
Figure 102-13. Anatomic relation-
ships of the internal auditory canal, laby-
rinth, carotid artery, facial nerve, and
trigeminal nerve. GSPN, greater superfi -
cial petrosal nerve.

Chapter 102
Petrosal Approaches 1031
third division of the trigeminal nerve are identifi ed. To
expose the horizontal petrous carotid artery, bone must
be removed medial to the middle meningeal artery and
inferomedial to the GSPN, from the facial hiatus to the
sphenopetrosal groove. Attempts should be made to
preserve the GSPN whenever possible to avoid postop-
erative “dry eye” secondary to impaired lacrimation. In
rare cases the GSPN may be sacrifi ced to prevent trac-
tion injury to the geniculate ganglion.
The horizontal segment of the petrous carotid
artery lies under the GSPN and runs along an axis
approximately 15 degrees medially to the course of the
GSPN (Fig. 102-16). A natural bony dehiscence of the
carotid canal can often be found immediately posterior
to the V3 division of the trigeminal ganglion, and the
internal carotid artery may easily be injured in this loca-
tion. If this natural bony dehiscence is absent, a window
of bone over the petrous carotid artery can be drilled
down to eggshell thickness and then carefully elevated
off the carotid artery. A blunt elevator is then used to
free the carotid artery and its surrounding periosteum
from the bony canal. A 2-mm rongeur can be used to
complete bone removal around the carotid artery in
piecemeal fashion. A 180-degree circumference of the
bone of the carotid canal should be removed to provide
adequate access for reliable vascular control at the time
of tumor removal. Bony dissection can then proceed in
a posterolateral direction along the horizontal course
of the petrous carotid canal to expose the genu and
vertical segments of the carotid artery.
At the genu of the petrous carotid artery, the eusta-
chian tube and tensor tympani muscle course supero-
lateral to the vertical segment of the carotid artery (Fig.
102-17). When pursuit of a lesion involves exposure of
the genu and vertical segment of the petrous carotid
artery, the eustachian tube and tensor tympani must be
transected, thus compromising middle ear function
and increasing the risk for postoperative CSF rhinor-
rhea. In such cases, the eustachian tube must be clearly
identifi ed and oversewn at the conclusion of the
procedure.
Wound closure is accomplished in layered fashion,
beginning with a watertight dural closure. The craniot-
omy bone plate is replaced and secured with a micro-
Middle
meningeal
artery
Lesser
petrosal
nerve
Foramen
spinosum
GSPN
Figure 102-14. Anatomic relationship of the middle meningeal
artery to the lesser and greater superfi cial petrosal nerves. GSPN,
greater superfi cial petrosal nerve.
Figure 102-15. The middle meningeal artery is coagulated and
divided.
Basal turn
of cochlea
Internal auditory canal
Carotid artery
Middle meningeal
artery
GSPN
Geniculate
ganglion
Figure 102-16. Anatomic relationships of the petrous carotid
artery. GSPN, greater superfi cial petrosal nerve.
Tensor tympani muscle
Petrous
carotid
artery
(vertical
segment)
Petrous
carotid
artery
(genu)
Petrous
carotid artery
(horizontal
segment)
Eustachian
tube
Figure 102-17. Dissection of the carotid artery to the level of the
eustachian tube and tensor tympani muscle.

1032
Section 11
Cranial Base Surgery
plating system. The temporalis muscle is reapproximated
and the overlying soft tissues are closed in two layers. A
mastoid dressing is then left in place for 72 hours and
the patient is observed in the hospital for 4 to 5 days.
Petrous Apicectomy
The middle fossa approach can be extended to allow
further exposure of the petrous apex. This approach
may be useful in the management of neoplastic and
infl ammatory lesions of the petrous apex, including
petrous apicitis. The petrous apex is a pyramidal region,
also referred to as Kawase’s rhomboid, in the antero-
medial aspect of the temporal bone with variable
degrees of pneumatization. It is bordered superomedi-
ally and inferomedially by the superior and inferior
petrosal sinuses, respectively9; the trigeminal nerve and
ganglion anterosuperiorly; the IAC, cochlea, and genic-
ulate ganglion posteriorly; the GSPN laterally; and
the petrous carotid anteriorly and inferolaterally (Fig.
102-18).
The key landmarks for the petrous apex are the
IAC and the horizontal petrous carotid artery, which
defi ne the fi eld of dissection to ensure exposure of the
petrous apex and preservation of the cochleovestibular
and facial nerves. Several methods have been described
to locate the IAC along the fl oor of the middle cranial
fossa. Early approaches describe following the GSPN
posteriorly from the facial hiatus to the geniculate gan-
glion and then along the labyrinthine segment of the
facial nerve to the IAC.10 This approach places the laby-
rinthine segment of the facial nerve and the cochlea at
risk for injury. A second method proposes using the
arcuate eminence (superior semicircular canal) as the
major landmark to localize the IAC because the IAC lies
along a 60-degree plane from the ampulla of the supe-
rior semicircular canal. However, this approach, which
involves skeletonizing the superior semicircular canal
to view the ampulla, increases the risk of sensorineural
hearing loss secondary to violation of the vestibular
labyrinth. Our group uses the technique described by
Garcia-Ibanez.11-14 The IAC is located medially by drill-
ing along the medial border of the petrous temporal
bone along a line bisecting the 120-degree angle formed
by the arcuate eminence and the GSPN (Fig. 102-19).
Bony dissection may be accomplished with a 2- to 3-mm
diamond burr until the porus acusticus is identifi ed.
Drilling is then continued laterally toward the fundus
to unroof the entire length of the IAC. At the fundus,
bone resection is limited anteriorly by the basal turn of
the cochlea and posteriorly by the ampulla of the supe-
rior semicircular canal and the vestibule. The petrous
carotid artery is then identifi ed as described earlier.
With the IAC and petrous carotid artery skeleton-
ized, the petrous apex can be drilled out to provide
exposure of the posterior fossa all the way anterior to
the precavernous portion of the ICA and medially to
the inferior and superior petrosal sinuses (Fig. 102-20).
The fi nal limits of this extended middle fossa exposure
are the inferior petrosal sinus inferiorly, the horizontal
petrous carotid artery laterally, the gasserian ganglion
anteriorly, and the IAC posteriorly. After complete
petrous apicectomy, the superior petrosal sinus is ligated
to allow opening of the tentorium to the incisura,
thereby exposing the contents of the middle and pos-
terior cranial fossae (Fig. 102-21).
Wound closure and postoperative care are as
described for the middle fossa approach.
Posterior Petrosal Approaches
Depending on the patient’s preoperative hearing status
and the need for additional surgical exposure, a retro-
labyrinthine, partial labyrinthine, translabyrinthine,
transcochlear, or complete petrosectomy approach is
chosen. The patient is positioned supine with the head
turned to the opposite side and the ipsilateral shoulder
raised slightly. Intraoperative facial nerve monitoring is
established at the beginning of the procedure. Paralytic
agents are not used after induction of general anesthe-
sia. Brain stem auditory evoked responses are also mon-
itored routinely because hearing preservation is desired.
Inferior
petrosal
vein
Petrous
apex
Trigeminal
ganglion
V1
V2
V3
Carotid
artery
GSPN
External
auditory
canal
Superficial
petrosal
vein
Figure 102-18. Anatomy of the petrous apex. GSPN, greater super-
fi cial petrosal nerve.
Arcuate eminence
GSPN
60°
60°
Figure 102-19. Landmarks for the internal auditory canal. GSPN,
greater superfi cial petrosal nerve.

Chapter 102
Petrosal Approaches 1033
Internal auditory
canal
Petrous
apex
Carotid
artery
GSPN
Figure 102-20. Removal of the petrous apex
after exposure of the petrous carotid artery and
the internal auditory canal. GSPN, greater super-
fi cial petrosal nerve.
Trigeminal
nerve
Middle clivus
Brain stem
Seventh and eighth
cranial nerves
Figure 102-21. Intracranial exposure via a transpetrous apex
approach.
Figure 102-22. Skin incision for a combined anterior and poste-
rior petrosal approach.
Perioperative medications administered include broad-
spectrum antibiotics with good CSF penetration (Cef-
triaxone, 2 g); furosemide (Lasix, 20 mg); mannitol,
0.5 mg/kg; and dexamethasone, 10 mg. Bacitracin
(50,000 U/L of saline solution) is used in the irrigation
fl uid. Lumbar drainage is not routinely performed.
The planned incision is injected with a solution of
1% lidocaine with 1 : 100,000 epinephrine. A large C-
shaped postauricular skin incision is made and extended
superiorly above the pinna to provide surgical exposure
for the temporalis muscle and inferiorly to expose the
mastoid tip, as shown in Figure 102-22. This incision
may be modifi ed according to the bony exposure
required. If hearing is absent, the external auditory
canal is transected and oversewn. Anterior and poste-
rior skin fl aps are elevated over the temporalis fascia
and mastoid periosteum. The frontal branch of the
facial nerve is preserved as described earlier. The tem-
poralis muscle is incised along its attachment along
linea temporalis. Posteroinferiorly, this incision is
extended through the mastoid periosteum to the
mastoid tip to develop a large anteroinferiorly based
musculoperiosteal fl ap (Fig. 102-23). Exposure of the
lateral surface of the skull is demonstrated in Figure
102-24. Inferiorly, the external auditory canal and
glenoid fossa are identifi ed. Anteriorly, the frontal,

1034
Section 11
Cranial Base Surgery
We prefer to perform the temporal craniotomy,
removal of the zygomatic arch, and mastoidectomy in
separate segments (Fig. 102-25). The temporal craniot-
omy plate and zygomatic arch can then be reattached
at closing with a microplating system. It is also possible
to perform the bone work in such a manner that the
temporal craniotomy and mastoid cortex are removed
en bloc with or without the zygomatic arch and glenoid
fossa (Fig. 102-26).
To create a bone fl ap that includes a temporal cra-
niotomy and a large portion of the mastoid cortex, the
sigmoid sinus is exposed from the level of the jugular
bulb to the confl uence of the sigmoid sinus, superior
petrosal sinus, and transverse sinus (Fig. 102-27).
Approximately 2 cm of bone is removed posteriorly
over the transverse sinus. Once the sigmoid and trans-
verse sinuses are exposed, the mastoid cortex is cut with
a small cutting burr along the external auditory canal
forward into the glenoid fossa. Burr holes are made
anteriorly in the temporal fossa, posteriorly above the
transverse sinus, and superiorly near the insertion of
the temporalis muscle (Fig. 102-28). A footed attach-
ment on a craniotome is used to cut a temporal crani-
otomy, and the mastoid cortex is freed from the
underlying air cells and middle fossa plate with a small
cutting burr and chisel.
The zygomatic arch is removed along with the roof
of the glenoid fossa by dividing the junction of the
zygomatic arch and malar eminence via a chevron-
shaped osteotomy with an oscillating saw. The glenoid
fossa osteotomies are then performed medial to the
glenoid fossa to allow removal of the zygomatic arch
along with the roof of the glenoid fossa. Exposure of
the middle and posterior fossa dura after completion
of the initial bone work is shown in Figure 102-29.
Figure 102-23. Musculoperiosteal fl ap. (Redrawn from Cass SP,
Sekhar LN, Pomeranz S, et al: Excision of petroclival tumors by a total petro-
sectomy approach. Am J Otol 15:474-484, 1994.)
Figure 102-24. Surface anatomy of the exposed cranium.
sphenoid, and temporal bones are exposed at the
pterion.
Osteotomies of the zygoma, a temporal craniotomy,
and a mastoidectomy are performed. The size of the
temporal craniotomy and the extent of petrosal expo-
sure through the mastoid are determined by the size
and location of the tumor. The zygomatic arch and
glenoid fossa are removed to improve inferior expo-
sure, and a complete mastoidectomy is performed with
variable amounts of additional petrosal bone removal.
Figure 102-25. Cranial, zygomatic, and mastoid bone work sepa-
rated into three components.

Chapter 102
Petrosal Approaches 1035
Figure 102-26. Combined temporal craniotomy, osteotomy of the
zygoma, and preservation of the mastoid cortex.
Figure 102-27. Exposure of the sigmoid and transverse sinuses.
sura. The fourth cranial nerve should fi rst be isolated
and protected. With the posterior temporal lobe ele-
vated superiorly and the sigmoid sinus retracted poste-
riorly, wide fi eld access to the supratentorial and
infratentorial regions of the posterior cranial fossa is
obtained.
Figure 102-28. Outline of osteotomies within the mastoid and
temporal squama.
Superior
petrosal
sinus
Transverse sinus
Sigmoid
sinus
Mandibular
condyle
Trigeminal nerve
(V3 division)
Figure 102-29. Surgical exposure after craniotomy and before
transmastoid petrosal bone work.
The dura is opened along the fl oor of the temporal
fossa and in the presigmoid region. Care is taken to
locate and protect the vein of Labbé. The superior
petrosal sinus is coagulated and ligated. The tentorium
is divided parallel to the petrous ridge along the inci-

1036
Section 11
Cranial Base Surgery
Retrolabyrinthine Approach
The patient is placed supine with the ipsilateral shoul-
der elevated and the head turned to the opposite side
so that the mastoid process is at the highest point in the
fi eld. A complete mastoidectomy is performed with an
operating microscope, suction irrigation, and high-
speed cutting burr, as described in Chapter 115. Special
attention is paid to exposing the sigmoid sinus, jugular
bulb, fallopian canal, vestibular labyrinth, superior
petrosal sinus, middle fossa dura, and posterior fossa
dura (Fig. 102-30). The porus of the IAC is then exposed
by further removing bone medial to the superior and
posterior semicircular canals. The endolymphatic sac,
which lies over the posterior fossa dura between the
sigmoid sinus and posterior semicircular canal, is pre-
served along with the endolymphatic duct. The endo-
lymphatic duct and sac are useful landmarks to help
preserve the vestibular labyrinth, but violation of the sac
or duct increases the risk for sensorineural hearing loss.
The dura over the middle and posterior fossae is then
incised to expose the infratentorial portion of the
tumor (Fig. 102-31). Once the superior petrosal sinus
and tentorium are divided, both the supratentorial
and infratentorial portions of the tumor are exposed
(Fig. 102-32).
This approach alone provides exposure of the cer-
ebellopontine angle but does not offer the surgeon
adequate visualization of the anterior brain stem or
petroclival region. Adequate exposure of the medial
portion of the IAC is possible in most cases, but a high-
Figure 102-30. Dural exposure after an anterior and retrolabyrin-
thine petrosal approach and dural incisions.
IX, X
PICA
VII,
VIII
SCA
AICA
Temporal
lobe
Basilar a.
IV
V root
Figure 102-31. The infratentorial portion of the tumor is exposed
through the retrolabyrinthine petrosal approach.
Figure 102-32. Both the supratentorial and the infratentorial por-
tions of the tumor are exposed through the combined anterior and
posterior petrosal exposure. AICA, anterior inferior cerebellar artery;
PICA, posterior inferior cerebellar artery; SCA, superior cerebellar
artery.