100
Fig. 7.3 The combined petrosal approach, which pro-
vides both infra- and supratentorial access (a). The patient
is placed in the full lateral position (b), with extensive
padding (c). After removal of the L-shaped bone flap
extending in the temporal-occipital region to the suboc-
cipital region, the outline of the cosmetic mastoidectomy
is planned with cutting through the outer table of bone at
the perimeter of the mastoid. After the outer table of the
mastoid is removed, the mastoid resection is performed.
The amount of bone removal is based on the status of
hearing and need for basal exposure. The dural incision is
then planned (d). Opening of the dura is done carefully in
the region of the transverse-sigmoid junction, and the
entrance of the vein of Labbé is preserved into this region.
There is variability (and sometimes multiplicity) of
venous drainage from the posterior temporal lobe in this
region, and one must open the dura carefully to under-
stand the individual drainage. The superior petrosal sinus
is then ligated in a location to ensure the drainage of the
temporal lobe is not embarrassed. After the superior
petrosal sinus is ligated, the tentorium is then divided
along the region of the petrous apex. The trochlear (fourth
cranial) nerve is located, and the tentorium is cut posteri-
orly to where the nerve enters the tentorial edge. This
maneuver then enables posterior retraction of the sigmoid
sinus and cerebellum from the region of the petrous bone
(e). (f) All cranial nerves are preserved during dissection
and removal of the tumor. (g) Completion of tumor
removal. (h–j) Case of large petroclival tumor that was
removed with a combined petrosal approach. In this case,
hearing was intact and the mastoidectomy was performed
to preserve the labyrinth. The closure of the cosmetic
mastoidectomy demonstrating replacement of the bone
flap (k), preoperative MRI with gadolinium (l), and fat
graft on placement on the postoperative CT scan (m) (a–g
Reproduced with permission from Liu and Couldwell
[ 32 ]; k–m Reproduced with permission from Couldwell
and Fukushima [ 25 ])A. Raheja and W.T. Couldwell