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Austin Journal of Otolaryngology
Review Article
Endoscopic Endonasal Approaches to the Skull Base - A
Review
Muto J1,3, Carrau RL1,2, Prevedello DM1,2*, Ditzel
Filho LFS1, de Lara D1, Kasemsiri P2, Otto BA1,2
and Yoshida K3
1
Departments of Neurosurgical Surgery, Ohio State
University, USA
2
Otolaryngology- Head and Neck Surgery, Ohio State
University, USA
3
Department of Neurosurgery, Keio University School of
Medicine, Japan
*Corresponding author: Daniel M Prevedello,
Department of Neurosurgery, Ohio State University,
N-1011 Doan Hall, 410 W. 10th Avenue, Columbus, OH,
43210, USA
Received: November 20, 2014; Accepted: September
01, 2015; Published: September 05, 2015
Abstract
In the past decade, endoscopic endonasal approaches (EEAs) have
progressed greatly, becoming an alternative to conventional transcranial
approaches. EEAs to the ventral skull base may be categorized anatomically
into five sagittal plane modules (transcribriform, transplanum, transsellar,
transclival, transodontoid) and eight coronal plane modules (orbit, petrous apex,
infrapetrous, suprapetrous, cavernous sinus, infratemporal fossa, condyle,
jugular foramen). A safe and effective use of these techniques requires a deep
understanding of pertinent anatomical landmarks and technical nuances to
minimize patient morbidity.
EEAs are useful approaches to the ventral skull base and craniocervical
junction and hold great potential for evolutionary progress when coupled with
careful patient selection, adequate training and experience. This manuscript
describes and discusses important anatomical landmarks and critical aspects
of the surgical technique used in each module, complementing their review with
case illustrations.
Keywords: Endonasal endoscopic approach; Coronal module; Sagittal
module; Indications and limitations; Skull base; Reconstruction
Abbreviations
Sagittal Plane Approaches
CT: Computed Tomography; MR Imaging: Magnetic Resonance
Imaging; CS: Cavernous Sinus; GG: Gasserian Ganglion; EEA:
Endonasal Endoscopic Approach; ICA: Internal Carotid Artery;
MPP: Medial Pterygoid Plate; LPP: Lateral Pterygoid Palate; MPW:
Medial Pterygoid Wedge; VA: Vertebral Artery; BA: Basilar Artery;
ACA: Anterior Cerebral Arterie; MOCR: Medial Optic-carotid
Recess; VBJ: Vertebrobasilar Junction; V2: Maxillary Division of the
Trigeminal Nerve; SOF: Supraorbital Fissure
Endonasal endoscopic approaches in the sagittal plane include
five modules, namely the transcribiform, transplanum, transsellar,
transclival, and transodontoid approaches. These modules can be
combined according to the complexity of the lesion at hand. Essential
key points are summarized in.
Introduction
Transcribiform approach (Figure 1)
This module exposes the area between the posterior ethmoidal
arteries and the frontal sinus; thus, it is defined by the removal
of the cribriform plate. Its limits are bounded by the lamina
A first attempt to perform endonasal endoscopic skull base
surgery dates back a century. Initially these efforts were restricted to
the pituitary fossa via transsphenoidal approaches [1]; however, with
the parallel evolution of instruments and visualization technology,
coupled with the ever increasing anatomical knowledge and surgical
experience, these techniques gradually have progressed to encompass
other areas of the cranial base [2,3].
Most EEAs include a trans-sphenoidal approach as the first step
to access the ventral skull base with the subsequent extension of the
approach relying on well-defined anatomy-based surgical modules
along the sagittal and coronal planes. Therefore, EEAs may be divided
into five modules in the sagittal plane (extending from the cribiform
to the odontoid) [4-6]; and eight modules in the coronal plane (from
paramedian internal carotid artery (ICA) to the jugular foramen)
[7,8].
This review describes the anatomical landmarks; indications and
limitations to these approaches to heightened awareness of their
efficacy and the understanding of their caveats.
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Figure 1: Transcribriform approach: A: Axial T1gadolinium enhanced
MRI showing the frontal base meningioma before surgery. B: Coronal MRI
showing the tumor originated from falx was attached to the frontal base. C:
Axial MRI showing subtotal resection of the tumor. D: Coronal MRI showing
partial resection of the tumor. E: operative image showing the left olfactory
nerve was preserved. The tumor underneath the frontal lobe was resected
completely. The residual tumor was located in the interhemispheric cistern.
Citation: Muto J, Carrau RL, Prevedello DM, Ditzel Filho LFS, de Lara D, et al. Endoscopic Endonasal
Approaches to the Skull Base - A Review. Austin J Otolaryngol. 2015; 2(7): 1055.
Prevedello DM
Figure 2: Transplanum approach: A: a preoperative axial T1 weighted
gadolinium enhanced MRI showing craniopharyngioma extended to
suprasellar lesion. B: Coronal MRI showing the tumor pushed up the floor of
third ventricle and contained the cystic lesion. C: Sagittal postoperative MRI
showing the complete tumor removal. D: Coronal MRI showing stalk and the
third ventricle was intact. E: operative image showing the tumor behind the
pituitary gland. F: operative image showing the tumor removed totally. The
lamina terminalis was open and the arachnoid over the chiasm and optic
nerve was preserved intact.
papyracea laterally; the frontal sinuses anteriorly and the posterior
ethmoidal arteries posteriorly. Therefore; the approach requires an
extended posterior septectomy; complete anterior and posterior
ethmoidectomies and a bilateral frontal sinusotomy (Draf III or
endoscopic Lothrop sinusotomy). Its most critical anatomical
landmarks are the anterior and posterior ethmoidal arteries.
Suitable indications for this approach include olfactory groove
meningiomas, esthesioneuroblastomas, certain craniopharyngiomas,
and pituitary adenomas that extend into the anterior cranial fossa.
Lesions that cross the mid-orbital roof (i.e. meridian of the orbit)
laterally are not amenable to a complete resection by this approach.
Transplanum/Transtuberculum approach (Figure 2)
This module is defined by the removal of the planum sphenoidale
and tuberculum sellae. Its lateral limits are the optic canals and
paraclinoid ICAs, its anterior limit is the posterior ethmoid arteries
and the posterior limit is the most antero-superior aspect of the
sella turcica. A resection that extends further anteriorly incurs
the risk of injuring the olfactory nerve and epithelium. Therefore,
these approaches require a posterior septectomy, wide bilateral
sphenoidotomies, posterior ethmoidectomies and removal of the
planum sphenoidale with or without a sellotomy.
The most critical anatomical landmark in this module is the
medial optic-carotid recess (MOCR) [4]. In suprasellar lesions, the
anterior cerebral arteries (ACAs) with its perforators, the superior
hypophyseal artery, the pituitary stalk and optic chiasm are both
critical structures and important landmarks.
Suitable indications for this approach are planum sphenoidale
or tuberculum sellae meningiomas, craniopharyngiomas, pituitary
adenomas, chordomas and chondrosarcomas with suprasellar
extension. Relative limitations of this approach include tumors that
extend above the ICA or roof of optic canal, across the midline of the
orbital meridian, or into the middle cranial fossa.
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Figure 3: Transsellar approach: A: a preoperative axial T1gadolinium
enhanced sagittal MRI showing the pituitary tumor extended in the suprasellar,
attached the optic nerve. B: Coronal MRI showing the tumor extended to
cranial side. C: Sagittal postoperative MRI showing the complete tumor
removal. D: a Coronal MRI showing stalk spared completely. E: epicapsular
dissection was performed. The pituitary stalk was located behind the tumor.
F: The view after the tumor removal completely showing pituitary stalk was
intact and pituitary gland was preserved intact.
Trans-sellar approach (Figure 3)
This module may be considered the most basic EEA. It requires
a posterior septectomy and wide bilateral sphenoidotomies, as
well as partial posterior ethmoidectomies to obtain a panoramic
view of the sellar face and floor. These steps are followed by a wide
sellotomy, exposing the superior and inferior intercavernous sinuses
and the bilateral cavernous sinuses. This broad exposure facilitates
intrasellar dissection and tumor removal. The removal of the sellar
floor facilitates maneuverability of instruments in the sella; thus, it is
routinely performed. The most important key anatomical structures
are the “four blues”, which comprise the superior and inferior
intercavernous sinuses rostrocaudally and the cavernous sinuses
laterally.
Suitable indications for this approach are pituitary adenomas,
Rathke’s cleft cysts and craniopharyngiomas. According to the
location of tumor, this approach can be combined with transplanum
and transclival approaches to access intradural lesions [4]. Its
limitations include tumors that extend laterally beyond the ICA and
cavernous sinuses.
Transclival approaches (Figure 4)
This module allows a partial (upper, middle or lower clivus) or
complete removal of the clivus. It includes a posterior septectomy
and bilateral removal of the rostrum and floor of sphenoid sinus.
Approaches to the lower clivus requires a posterior and superior
nasopharyngectomy (i.e. removal of mucosa, paraspinal muscles and
pharyngobasilar fascia to expose the clival bone); whereas, approaches
to the upper clivus may require a pituitary transposition.
Besides the segments of the ICA (parapharyngeal, petrous,
paraclival, parasellar), other relevant extradural anatomic structures
in this module include the cavernous sinus and basilar plexus in
the upper-third, Dorello’s canal in the middle-third, and the in the
condyles and hypoglossal canals in the inferior third. Intradurally,
at the level of the superior clivus, all significant anatomic structures
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choana without the need for sphenoid sinus exposure or clival drilling.
Critical anatomical landmarks include the tori tubari (Eustachian
tubes), the odontoid ligaments and the occipital condyles. Its inferior
limit is the body of C2 and laterally the lateral masses of C1. Most
often it is an extradural approach; therefore, the dura is the posterior
limit.
Figure 4: Transclival approach: A: a preoperative axial T1 gadolinium
enhanced MRI showing clivus chordoma extended into sphenoid sinus,
ethmoid sinus, cavernous sinus, right orbital cavity. B: Coronal MRI showing
the tumor pushed up the optic nerve and contains the cyst. C: postoperative
axial MRI and D: coronal (D) MRI showing the tumor removed completely.
E: operative image, showing the epidural tumor and clivus dura was intact
to protect the tumor extension to prepontine cistern. F: operative image
showing the tumor removed totally and tumor penetrate into the periosteum
dura partially. The basilar venous plexus between the two layers of the dura
was already occluded.
are related to the interpeduncular fossa, and are limited laterally
by the third cranial nerves and posteriorly by the mesencephalum
(mammillary bodies) and the vascular structures (basilar tip,
posterior cerebral arteries and superior cerebellar arteries). Lateral
limits of the approach include the parasellar ICAs for the upper
clivus; Dorello’s canal and the paraclival ICAs for the middle clivus;
and the hypoglossal canal and parapharyngeal ICA for the lower
clivus. The medial pterygoid wedge (MPW), defined as the most
medial projection of the base of the pterygoid plate as it meets the
floor of sphenoid sinus, is a critical anatomical landmark that heralds
the transition from petrous to the paraclival segments of the ICA [8].
In the middle-third, the approach reaches the prepontine cistern
containing the basilar artery and it is limited posteriorly by the pons
and laterally by the six cranial nerves, ascending to reach the dura
in the direction to Dorello’s canal. The inferior corridor reaches the
pre-medullary cistern comprising the vertebral arteries and is limited
laterally by the hypoglossal nerves and posteriorly by the medulla.
Key extradural landmarks include the medial pterygoid wedge and
tori tubari (Eustachian tubes). Suitable indications include clival
meningiomas, chordomas, chondrosarcomas and craniovertebral
invagination. Limitations of the approach include tumors extending
beyond the lateral limits defined above as the parasellar and
parapharyngeal ICA.
Transodontoid approach
This module facilitates the removal of the odontoid process of
C2. Therefore, the approach requires a posterior septectomy, bilateral
removal of the rostrum and floor of the sphenoid sinus and a posterior
and superior nasopharyngectomy, similar to the access to the lower
clivus with a caudal extension (nasopharyngectomy). The lower third
of the clivus and anterior arch of C1 are removed after dissection of
the nasopharyngeal mucosa and the longus capiti muscles [6]. This
approach generally can be performed directly through the posterior
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Suitable indications for this approach include degenerative/
inflammatory disease such as compressive pannus from rheumatoid
arthritis, basilar invagination, and tumors such as chordomas, and
chondrosarcomas. One limitation of the approach includes tumors
extending laterally beyond the condyles or vertebral arteries. As
this approach can potentially generate instability, the need for
craniocervical fixation needs to be considered on every case. Foramen
magnum meningiomas positioned posterior to the odontoid process
represent a relative contraindication, as the exposure could potentially
generate instability and the need for craniocervical fusion. A posterolateral approach seems more appropriate under these circumstances.
Coronal Plane Modules
Endonasal endoscopic approaches in the coronal plane are
further divided by depth into anterior, middle, and posterior [7]. The
anterior coronal plane is related to the anterior cranial fossa and the
orbit, the middle coronal plane to the middle cranial fossa, and the
posterior coronal plane to the posterior cranial fossa. Essential points
are summarized in.
Anterior Coronal Plane
Transorbital approach
Transorbital approaches require an uncinectomy, wide
antrostomy, and anterior and posterior ethmoidectomies. These
steps facilitate the removal of the lamina papyracea and the medial
wall of the optic canals. Transorbital approaches can be divided
into extraconal and intraconal. Extraconal approaches require the
removal of the medial wall of orbit. A latero-inferior displacement of
the orbital soft tissues enhances the visualization the orbital roof. This
approach may be combined with a transcribiform or transplanum
approach to obtain margins that extend laterally to include the medial
half of the orbital roof. Additionally, an orbital and/or optic nerve
decompression are included in this category. An intraconal approach
is indicated for lesions that are inferior and medial to the optic nerve.
A corridor between the inferior and medial rectus muscles is created
that provides adequate access to the lesion, and preserves extraocular
muscle function.
Crossing the optic nerve should be avoided; therefore, lesions
localized to the superior/lateral orbit are contraindications for this
technique.
Critical anatomical landmarks for this module include the optic
nerve and ophthalmic artery, as well as the anterior and posterior
ethmoidal arteries. The lateral limits are the optic nerve and
ophthalmic artery. Suitable indications for this approach include
inflammatory or autoimmune diseases (i.e. Grave’s exophtalmopathy)
and tumors such as orbital meningiomas, cavernous hemangiomas,
and osteomas.
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Middle Coronal Plane Modules
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Modules of the middle coronal plane include seven different
approaches to distinct anatomical areas: petrous apex, infrapetrous
area, suprapetrous area, cavernous sinus, infratemporal fossa, occipital
condyle and jugular foramen. The initial corridor for these modules
requires a transpterygoid approach. However, lesions located medial
to the petrous apex region may be approached through a simpler
trans-sphenoidal corridor.
the lateral pterygoid plate (LPP) is followed laterally to the foramen
ovale. Foramen ovale and V3 are situated superficial (i.e. anterior)
to the petrosal ICA. The medial limit is the vidian nerve, while the
superior limit is the petrosal ICA. The most critical anatomical
landmarks in this module are the facial, cochlear and vestibular
nerves and Eustachian tube laterally, the petrosal ICA superiorly
and the hypoglossal nerve inferolaterally. Suitable indications for
this approach include cholesterol granulomas, chordomas, and
chondrosarcomas.
Transpterygoid corridor
Suprapetrous approach
This is a basic step to most of the modules in the middle coronal
plane. Its basic format can be extended to accommodate the extent
of the tumor resection. The sinonasal component includes passing
through the natural space of the maxillary sinus after removing the
middle turbinate and completing an uncinectomy, anterior and
posterior ethmoidectomies, and a large mid-meatal nasomaxillary
window. Extensive lesions may require a medial maxillectomy or
even an endoscopic Denker’s approach to expose the entire posterior
wall of the antrum and extend the line of sight laterally.
This module is represented by the quadrangular space approach,
which provides access to Meckel’s cave. The quadrangular space is a
potential space limited medially and inferiorly by the ICA, laterally
by maxillary nerve, and superiorly by the abducens nerve running
inside the cavernous sinus [9]. This corridor demands removal of
the medial and posterior walls of maxillary sinus. The soft tissues
in the sphenopalatine fossa are mobilized laterally facilitating the
identification of the vidian nerve and V2. The vidian canal (and its
neurovascular bundle) and V2 are followed posteriorly to identify the
petrous ICA, and to reach the Gasserian ganglion (GG) [8,10]. By
drilling the lateral bone over the ICA, the periosteum of the middle
fossa is exposed. The periosteum and dura are opened over the
quadrangular space to access Meckel’s cave. The abducens nerve runs
within the cavernous sinus as it travels toward the supraorbital fissure
at the level of V1 [11-13].
Once this corridor is opened, the sphenopalatine and posterior
nasal arteries are transected at the level of the sphenopalatine
foramen. The posterior wall of the maxillary sinus and the ascending
process of the palatine bone are removed; and the soft tissues of
the pterygopalatine fossa are mobilized laterally, exposing the
vidian canal, vidian nerve and the foramen rotundum and V2 over
the anterior and superior aspect of the pterygoid process. Proper
identification and preservation of these landmarks are followed by
the opening of the lateral recess of the sphenoid sinus and drilling
of the base of the pterygoid process; thus, allowing a direct access to
the medial aspect of the infratemporal fossa and middle cranial fossa.
Approach to the petrous apex
This approach is basically a lateral extension of a mid-clivus
approach [7], it is particularly useful when the tumor has protruded
into the sphenoid sinus and therefore created a “corridor”. Exposure
will mandate the isolation of the anterior genu of the ICA to access
the petrous bone). Bilateral sphenoidectomies are required (the
sphenoid floor is drilled until the clival recess is exposed. Key
anatomical landmarks include the medial pterygoid plate (MPP) and
the paraclival ICA. Removing the bone surrounding the ICA allows
lateralization of the vessel to grant access to the petrous apex.
Suitable indications for this approach include cholesterol
granulomas, chordomas, and chondrosarcomas. The most critical
anatomical landmarks in this module are the vidian nerve, the
abducens nerve at Dorello’s canal and the carotid canal.
All subsequent approaches in the middle and coronal planes
employ a transpterygoid approach using the maxillary sinus as a
working corridor.
Infrapetrous approach
The working corridor for this approach comprises the fossa of
Rosenmüller, the lateral sphenoid recess and medial maxilla. Bilateral
sphenoidectomies and a posterior maxillectomy are required; the
sphenoid floor is drilled until the clival recess is exposed. The medial
pterygoid plate is followed laterally to the foramen rotundum and
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This module is used to access lesions located in the anteromedial
segment of Meckel’s cave [9]. The most critical anatomical landmark
are V2 laterally, the ascending ICA medially, the abducens nerve
in the cavernous sinus superiorly, and the petrous ICA inferiorly.
Suitable indications for this approach include invasive pituitary
adenomas, meningiomas, trigeminal schwannomas, and adenoid
cystic carcinomas.
Cavernous sinus approach
This area, located lateral to the sella, contains the oculomotor,
trochlear and abducens nerves. This approach requires a posterior
ethmoidectomy and sphenoidectomy. Removal of the overlying
bone may decompress the nerves in the cavernous sinus; however,
aggressive surgical maneuvering may cause neurological deficits. To
enter the cavernous sinus, the dural opening is made just above the
quadrangular space.
Suitable indications for this approach include patients with
tumors in this region presenting with oculomotor, trochlear, optic
or abducens nerve palsies. The most critical anatomical landmarks in
this module are the oculomotor, trochlear, ophthalmic and abducens
nerves and the cavernous ICA with its accompanying sympathetic
fibers.
Infratemporal approach
This module requires a medial maxillectomy-transmaxillary
approach (with or without an endoscopic Denker’s maxillotomy)
[7]. Angled endoscopes are especially useful in this approach. After
completing a medial maxillectomy, the dissection continues laterally
identifying and ligating the internal maxillary artery and its branches.
The soft tissues in the sphenopalatine fossa are mobilized laterally. The
medial pterygoid plate and the foramen rotundum (canal) are drilled
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until the pterygoid process is flush with the middle cranial fossa. The
dissection is continued laterally identifying the lateral pterygoid plate,
which can be followed posterolaterally to the foramen ovale.
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Posterior Coronal Plane
of key landmarks: the canal of the internal carotid artery, medial
pterygoid plate, and vidian canal. The removal of infrapetrous bone,
tracing the petroclival synchondrosis, posterolateral to the Eustachian
tube, allows identification of the jugular foramen. Positioning of the
endoscope at the fossa of Rosenmüller provides a panoramic view
that includes the soft palate caudally, the Eustachian tube laterally,
the pharyngobasilar fascia and floor of the sphenoid rostrally and the
nasopharyngeal mucosa in the depth. The most critical anatomical
landmarks are the sheath of the parapharyngeal ICA, its contents
(jugular vein and lower cranial nerve IX, X, XI) and the hypoglossal
nerve. Suitable indications for this approach include schwannomas,
meningiomas, and certain paragangliomas.
Condylar approach
Discussion
The most critical anatomical landmarks for this module are the
ICA (pharyngeal and petrous segments), the medial pterygoid plate,
the lateral pterygoid plate and Eustachian tube. Suitable indications
for this approach include schwannomas, meningiomas and invasive
carcinomas. In these cases the surgical-imaging correlation provided
by a surgical navigation system is particularly useful, as the osseous
landmarks can be destroyed by invasive tumors.
As in the previous module, this approach requires a medial
maxillectomy-transmaxillary approach (with or without an
endoscopic Denker’s maxillotomy). Resection of the medial aspect of
the Eustachian tube is also necessary to extend the lateral exposure.
This module grants access to lesions posterior to the Eustachian tube
and medial to the parapharyngeal ICA. This corridor contains the
fossa of Rosenmüller, the occipital condyle and hypoglossal canal.
The most critical anatomical landmark is the Eustachian
tube, which can help to determine the position of the ascending
parapharyngeal segment of ICA. Suitable indications for this
approach include schwannomas, meningiomas, paragangliomas,
chordomas and chondrosarcomas. Certain tumors, especially
chordomas and chondrosarcomas can invade the hypoglossal canal
and further extend laterally to jugular foramen.
Jugular foramen approach (Figure 5)
This module requires wide bilateral sphenoidotomies and a
posterior and medial maxillectomy-transmaxillary approach (with or
without an endoscopic Denker’s maxillotomy) as well as transecting
or removing the pharyngobasilar fascia. This allows the identification
Endoscopic endonasal approaches represent an additional tool
for the management of lesions of the ventral skull base. Among the
advantages of EEAs is that due to its ventral pathway and the fact that
vital structures are typically displaced laterally by the tumor, there is
less need to dissect cranial nerves or retract the brain. Furthermore,
it allows direct devascularization in early stages of the procedure,
especially in meningiomas attached to the dura of the ventral
skull base. In extradural tumors, such as many chordomas and
chondrosarcomas, there is no need to open the dura mater via EEA.
Endoscopes provide high magnification and visualization. Thus,
structures may be inspected closely and the arachnoid plane could be
preserved while reducing vascular injury. In addition, angled scopes
offer visualization “around corners”, which results in decreasing
residual tumor and risk of neurovascular injury.
Surgeons’ experience is a key factor to obtain optimal outcomes.
The learning curve is steep and requires that the entire surgical team,
including otolaryngologists and neurosurgeons, become proficient in
the endoscopic technique and instrumentation. Lack of experience
and poor understanding of the anatomy could lead to catastrophic
complications.
CSF leakage is the most common major complication for both
endoscopic and open techniques. Its incidence varies widely from a
low range for transsphenoidal approach (2% [14,15] to 3.5%) [16]
to significantly higher incidence after conventional approaches to
the anterior skull base tumor (13% [17], 20.3% [18] 29%) [19]. For
endoscopic expanded approaches, the pedicled mucosal flaps provide
vascularized tissue that have led to primary healing significantly
improving the rates of postoperative CSF leaks. The proper surgical
techniques based on the anatomical understandings can lead to the
best surgical results.
Conclusion
Figure 5: Jugular foramen approach: A: preoperative axial section of T2weighted MRI showing a clival chordoma extending to the jugular foramen. B:
a preoperative coronal T1-weighted gadolinium enhanced MRI showing the
tumor homogenously enhanced and compress the pons. C: postoperative
axial MRI showing the flap well bolstered against the defect by balloon
packing. D: coronal T1-weighted gadolinium enhanced MRI showing the
complete resection of the tumor. E, F: Endoscopic view during the surgery.
The clivus dura was exposed and the tumor penetrated into the subdural
space. (E) The tumor extended to the jugular foramen was resected with
preservation of Eustachian tube (F).
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EEA to the ventral skull base are divided into five modules in
“sagittal plane” from the cribriform to the odontoid and eight modules
in “coronal plane” from paramedian to jugular foramen. Each module
is limited by tumor pathology, location of the lesion, relationships
with surrounding vital structures, surgical skills and experience,
and institutional resources. Understanding the limitations can help
selecting the appropriate approaches, occasionally combining two
or multiple approaches in order to avoid crossing the plan of cranial
nerves and important arteries.
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In well-selected patients, an EEA provides maximum effectiveness,
superior outcomes with minimal deficits and morbidities. Despite
improvements in instrumentation, techniques and anatomical
understanding, EEAs are not the solution to every skull base
lesion. Endoscopic approaches are not a substitute to conventional
approaches, but a complement. Therefore it is inevitable that skull
base surgeons should be familiar with all techniques to offer the best
surgical strategy for their patients.
References
1. Rosegay H. Cushing’s legacy to transsphenoidal surgery. J Neurosurg. 1981;
54: 448-454.
2. Couldwell WT, Weiss MH, Rabb C, Liu JK, Apfelbaum RI, Fukushima T.
Variations on the standard transsphenoidal approach to the sellar region, with
emphasis on the extended approaches and parasellar approaches: surgical
experience in 105 cases. Neurosurgery. 2004; 55: 539-547; discussion 547550.
9. Kassam AB, Prevedello DM, Carrau RL, Snyderman CH, Gardner P,
Osawa S, et al. The front door to meckel’s cave: an anteromedial corridor
via expanded endoscopic endonasal approach- technical considerations and
clinical series. Neurosurgery. 2009; 64: 71-82; discussion 82-83.
10.Fortes FS, Sennes LU, Carrau RL, Brito R, Ribas GC, Yasuda A, et al.
Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid
approach: development of a surgical instruction model. Laryngoscope. 2008;
118: 44-49.
11.Kocher M, Soffietti R, Abacioglu U, Villà S, Fauchon F, Baumert BG, et al.
Adjuvant whole-brain radiotherapy versus observation after radiosurgery or
surgical resection of one to three cerebral metastases: results of the EORTC
22952-26001 study. J Clin Oncol. 2011; 29: 134-141.
12.Alfieri A, Jho HD. Endoscopic endonasal approaches to the cavernous sinus:
surgical approaches. Neurosurgery. 2001; 49: 354-360.
13.Cavallo LM, Cappabianca P, Galzio R, Iaconetta G, de Divitiis E,
Tschabitscher M. Endoscopic transnasal approach to the cavernous sinus
versus transcranial route: anatomic study. Neurosurgery. 2005; 56: 379-389.
3. Zada G, Kelly DF, Cohan P, Wang C, Swerdloff R. Endonasal transsphenoidal
approach for pituitary adenomas and other sellar lesions: an assessment of
efficacy, safety, and patient impressions. J Neurosurg. 2003; 98: 350-358.
14.Semple PL, Laws ER Jr. Complications in a contemporary series of patients
who underwent transsphenoidal surgery for Cushing’s disease. J Neurosurg.
1999; 91: 175-179.
4. Kassam A, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded
endonasal approach: the rostrocaudal axis. Part I. Crista galli to the sella
turcica. Neurosurg Focus. 2005; 19: E3.
15.Fatemi N, Dusick JR, de Paiva Neto MA, Kelly DF. The endonasal microscopic
approach for pituitary adenomas and other parasellar tumors: a 10-year
experience. Neurosurgery. 2008; 63: 244-256.
5. Kassam A, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded
endonasal approach: the rostrocaudal axis. Part II. Posterior clinoids to the
foramen magnum. Neurosurg Focus. 2005; 19: E4.
16.Sudhakar N, Ray A, Vafidis JA. Complications after trans-sphenoidal surgery:
our experience and a review of the literature. Br J Neurosurg. 2004; 18: 507512.
6. Kassam AB, Snyderman C, Gardner P, Carrau R, Spiro R. The expanded
endonasal approach: a fully endoscopic transnasal approach and resection of
the odontoid process: technical case report. Neurosurgery. 2005; 57: E213.
17.Deschler DG, Gutin PH, Mamelak AN, McDermott MW, Kaplan MJ.
Complications of anterior skull base surgery. Skull Base Surg. 1996; 6: 113118.
7. Kassam AB, Gardner P, Snyderman C, Mintz A, Carrau R. 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. 2005; 19: E6.
18.Sekhar LN, Pranatartiharan R, Chanda A, Wright DC. Chordomas and
chondrosarcomas of the skull base: results and complications of surgical
management. Neurosurg Focus. 2001; 10: E2.
8. Kassam AB, Vescan AD, Carrau RL, Prevedello DM, Gardner P, Mintz AH, et
al. Expanded endonasal approach: vidian canal as a landmark to the petrous
internal carotid artery. J Neurosurg. 2008; 108: 177-183.
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19.Feiz-Erfan I, Han PP, Spetzler RF, Horn EM, Klopfenstein JD, Porter RW, et
al. The radical transbasal approach for resection of anterior and midline skull
base lesions. J Neurosurg. 2005; 103: 485-490.
Citation: Muto J, Carrau RL, Prevedello DM, Ditzel Filho LFS, de Lara D, et al. Endoscopic Endonasal
Approaches to the Skull Base - A Review. Austin J Otolaryngol. 2015; 2(7): 1055.
Austin J Otolaryngol 2(7): id1055 (2015) - Page - 06