81The Role of EEA
Endoscopic endonasal approaches provide the
most direct access to the ventral skull base.
Chondrosarcomas (usually originated at the
petroclival region) and chordomas (originated
at midline clivus) tend to displace neurovascu-
lar elements laterally, superiorly, and posteri-
orly. For that reason we advocate the use of
EEA as the initial surgical corridor. In a single
procedure, EEA allows access to multiple
skull base compartments avoiding extensive
retraction of neurovascular structures. It also
allows extensive drilling of the clivus, sphe-
noid bone, and petrous portions of the tempo-
ral bone, which are frequently invaded by
tumor.
For lesions located in the upper petroclival
region, cavernous sinus, and middle cranial fossa,
the transsphenoidal approach with removal of the
sphenoid and temporal bony encasement is indi-
cated. Tumors extending in the middle third of
the clivus can be approached through a transs-
phenoidal approach associated to clivectomy and
petrosectomy. Lesions in the lower clivus and
infratemporal fossa extension require a transpter-
ygoid approach.
Depending on the location of the tumor, some
other following steps may be necessary. Tumors
located inferior to the petrous apex may require
removal or mobilization of the Eustachian tube
(Fig. 6.4). Removing the pterygoid processes and
adjacent musculature can provide access to the
infratemporal fossa. In order to gain access to the
anterior portion of Meckel’s cave and medial
middle cranial fossa, the lateral sphenoid recess
must be accessed [ 15 ].
Chondrosarcomas and chordomas are often
soft; however, it sometimes can be hard and very
calcified. Usually, extensive bone removal to
expose the whole tumor is done before soft
tumor resection. Lateralization of the ICA allows
the removal of the paramedian tumor located on
the petroclival synchondrosis. Dissection within
the cavernous sinus, jugular foramen, infratem-
poral fossa, and high cervical region is per-
formed using stimulating dissectors to prevent
cranial nerve injuries.
Intradural Posterior Fossa Tumors
MeningiomasThe role of the expanded EEA in the manage-
ment of ventral posterior fossa meningiomas is
still restricted due to limited surgical indications
in selected cases [ 16 ]. However, when surgery is
well indicated, the surgeon may benefit from the
advantages of EEA such as direct access to ven-
tral skull base pathologies avoiding brain and
brainstem retraction, near-field magnification,
better surgical field illumination, and minimal
manipulation of neurovascular structures [ 1 – 5 ].
Nevertheless, unlike the EEA to sellar pathol-
ogy, there is a relative paucity of literature regard-
ing endoscopic management of posterior fossa
meningiomas. The probable reason is the combi-
nation of limiting factors including rarity of the
pathology and the indication of approaching it
through an EEA, technical challenges in tumor
resection and skull base reconstruction, expertise
of the surgical team, and available resources [ 16 ].
The current literature involving the endo-
scopic management of posterior fossa meningio-
mas consists in the collective experience of an
approach rather than experience with the particu-
lar type of tumor [ 16 – 25 ].
Ventral posterior fossa meningiomas are chal-
lenging lesions to manage independently of the
selected surgical approach and are unique tumors
in the type of pathological displacement of the
surrounding anatomy. Despite the recent reports
demonstrating the role of radiation therapy on
their management, surgical resection continues
to be the first and best treatment method aiming
the permanent tumor eradication [ 26 , 27 ].
The surgical outcomes for petroclival menin-
giomas, regardless of the approach used, have
greatly improved over the past decades with the
development of better microsurgical technique,
intraoperative monitoring, and radiological imag-
ing. Nevertheless, it is still associated with sig-
nificant morbidity specially regarding new cranial
nerve palsies or persisting/worsening of preexist-
ing palsies that range from 39% to 76% of the
patients [ 28 – 31 ].6 Endoscopic Endonasal Approach for Posterior Fossa Tumors