CHAPTER 37 The Posterior Petrosal Approach for the Treatment of Petroclival Meningiomas
OPERATIVE TECHNIQUE
Craniotomy Flap
The skin incision is made extending from the zygoma anterior to the tragus, and extending in a curvilinear fashion behind the ear to below the mastoid process (Fig. 37-1). The skin flap is rotated anteriorly and inferiorly, and the temporal fascia is incised and reflected inferiorly in continuity with the sternocleidomastoid muscle. The temporalis muscle is cut along the superior edge of the incision and retracted inferiorly and anteriorly (Fig. 37-2). This flap will be used at the time of closure to cover the drilled surface of the temporal bone. Once these maneuvers are complete, the bony surfaces of the temporal fossa, mastoid, and lateral posterior fossa are exposed.
Four burr holes are placed straddling the transverse sinus, two in the posterior fossa and two supranteriorly. One hole is made just medial and inferior to the asterion opens into the posterior fossa below the transverse–sigmoid sinus junction. Another hole located at the squamal and mastoid junction of the temporal bond along the projection of the superior temporal line opens into the supratentorial compartment. A single bone flap covering the middle and posterior fossae is made using the foot attachment of a high-speed drill using the burr holes on either side of the sinus for access. The burr holes flanking the sinus are then connected using a rongeur or the drill. Caution should be taken during this step to avoid injury to the venous sinus wall during this step. The transverse–sigmoid sinus junction is exposed with the craniotomy. Care should also be taken when removing the bone flap because in many patients the bone is very adherent to the dura at the junction of the transverse and sigmoid sinus (Fig. 37-3).