Skull Base Surgery of the Posterior Fossa

21

Fig. 1.11 Lateral and anterolateral approaches. (a) Left
subtemporal approach. The subtemporal approach requires
retraction of the temporal lobe to expose the lateral aspect of
the tentorial incisura. Bridging temporal veins can be at risk
of injury, which may cause a venous infarct of the temporal
lobe. (b) View through a left subtemporal approach. The
ambient, crural, and interpeduncular cisterns are exposed,
and the basilar apex can be accessed. The oculomotor nerve
is seen emerging between the superior cerebellar artery and
the posterior cerebral artery. The trochlear nerve has a close
relation with the superior cerebellar artery before it joins the
tentorial edge near the cavernous sinus. (c) The tentorium is
cut, taking care to preserve the trochlear nerve, to expose the
tentorial surface of the cerebellum. Anterior brainstem

exposure is blocked by the petrous temporal bone. (d) View

through subtemporal transtentorial approach combined with

an anterior petrosectomy. Kawase’s rhombus is limited by

the GSPN laterally, mandibular branch of the trigeminal

nerve anteriorly, and the arcuate eminence posteriorly. (e)

View through a right frontotemporal-orbitozygomatic

approach. This allows for several operative corridors,

including transsylvian, pretemporal, and subtemporal. (f)

View through a right transcavernous exposure of the basilar

apex region. The anterior clinoid has been removed, and the

posterior cavernous sinus has been opened by skeletonizing

the oculomotor and trochlear nerves. This facilitates mobili-

zation of these nerves and drilling of the posterior clinoid

and dorsum sella

1 Surgical Anatomy of the Posterior Fossa