Skull Base Surgery of the Posterior Fossa

137

plane of the dentate ligament, a midline posterior
approach is indicated. Midline anterior tumors
without significant spinal extension may appear
at first glance to be best approached via an endo-
scopic endonasal route (EEA), if the tumor is
located on the anterior rim of the foramen mag-
num, the origin is medial to the hypoglossal canal
and jugular foramen with posterior and lateral
displacement of the lower cranial nerves.
However, significant inferior extension would
necessitate removal of the anterior arch of C1, the
C2 odontoid process, and the ligamentous com-
plex that provides stability at the craniocervical
junction. Therefore these tumors are usually
managed via a posterolateral approach [ 4 ]. The

proponents of the EEA would state that it allows

for tumor resection without retraction of brain

tissue and does not necessitate crossing the plane

of the cranial nerves. In anteriorly based tumors,

this approach allows for early access to the dural

blood supply with improved visualization during

tumor resection and decreased intraoperative

blood loss. Also, involved bone and dura may be

resected more easily as compared to a more lat-

eral trajectory. Our objection to utilizing the EEA

to intradural meningiomas is based on five cate-

gories of pitfalls. First, the bony removal in this

approach necessitates reconstruction of the skull

base and is accompanied by a significant risk of

CSF leak [ 11 ]. Second, lower rates of complete

Fig. 10.1 MRI of a 38-year-old female presenting with
headaches and dysphagia. (a–c) Preoperative imaging. (a,
b) T1-weighted image with gadolinium demonstrating an
anteriorly located FMM eccentric to the right. (c)

T2-weighted image. (d–f) Postoperative imaging T1

weighted with gadolinium demonstrating successful

resection of the tumor

10 Foramen Magnum Meningiomas