Surgical Management of Petroclival Meningiomas: Factors Determining the Choice of Approach

Kadir Erkmen, MD; Svetlana Pravdenkova, MD, PhD; Ossama Al-Mefty, MD

Disclosures

Neurosurg Focus. 2005;19(2) 

In This Article

Description Of Approaches

The surgical approaches used in the resection of petroclival tumors have been described in the past. The following is a summary of each of these approaches.

The patient is positioned supine on the operating table with a shoulder roll placed under the ipsilateral shoulder.[12] The head is turned to the contralateral side and the vertex is dropped. A curvilinear incision is made beginning anterior to the tragus at the level of the zygomatic arch, and is continued behind the hairline to the midline. The flap is rotated anteriorly. The superficial and deep layers of the temporal fascia are elevated with the skin flap to protect the frontal branch of the facial nerve. The zygomatic arch is cut anteriorly and posteriorly, and the temporalis muscle is elevated and retracted inferiorly. A craniotomy is made along the floor of the middle fossa and crossing the sphenoid wing. The dura mater is elevated from the floor of the middle fossa until the middle meningeal artery is encountered. This vessel is coagulated and cut. As the dura mater is elevated farther, the foramen ovale and third division of the trigeminal nerve are identified. The greater superficial petrosal nerve is identified and carefully dissected to prevent traction injury to the geniculate ganglion. The dura is separated from the lateral wall of the cavernous sinus along the third and second divisions of the trigeminal nerve until the gasserian ganglion is exposed and the trigeminal impression is encountered. The bone of the petrous apex is drilled medially to the carotid artery, extending from the trigeminal impression to the IAM, and exposing the posterior fossa dura (Fig. 1A). The dura mater is opened along the base of the temporal lobe. The superior petrosal sinus is coagulated and cut to allow opening of the tentorium to the incisura, exposing the middle and posterior cranial fossae (Fig. 2).

Postoperative CT scans obtained in patients undergoing the petrosal approaches. The examples demonstrate the extent of petrous bone resection based on the approach chosen. A: Resection of the petrous apex in an anterior petrosal approach. B: Resection of the retrolabyrinthine petrous bone in a posterior petrosal approach. C: Combined petrosal approach in which the petrous apex and retrolabyrinthine bone have been resected. The IAM, middle ear apparatus, and labyrinth are intact. D: Complete petrosectomy, with resection of the entire petrous temporal bone, except for a thin shell of bone surrounding the seventh cranial nerve.

Illustration depicting the exposure provided by the anterior petrosal approach. The petrous apex has been resected from the trigeminal impression to the IAM. The middle fossa dura mater is opened and the tentorium is cut after coagulation of the superior petrosal sinus.

The patient is positioned supine with the head turned to the opposite side and the ipsilateral shoulder raised slightly.[3,4] A skin incision is made extending from the zygoma anterior to the ear, and extending in a curvilinear fashion behind the ear to below the mastoid process. 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. Four burr holes are placed straddling the transverse sinus, two in the posterior fossa and two supratentorially. A single bone flap is created covering the middle and posterior fossae (Fig. 3). The transverse–sigmoid sinus junction is exposed with the craniotomy. The mastoid cortex is scored and cut, and a mastoidectomy is performed, exposing the presigmoid dura mater, and keeping the bone labyrinth intact (Fig. 1B). The sigmoid sinus is skeletonized to the jugular bulb. The dura is opened along the floor of the temporal fossa and in the presigmoid region. Care is taken to locate and protect the vein of Labbé at its insertion into the sigmoid sinus. The superior petrosal sinus is coagulated or occluded with a clip, and then it is cut to connect the dural openings. The tentorium is sectioned in a parallel plane to the petrous ridge and across the incisura after the surgeon locates and preserves the fourth cranial nerve insertion (Fig. 3). The posterior temporal lobe is elevated and the sigmoid sinus is retracted posteriorly, allowing access to the supra and infratentorial spaces (Fig. 4).

Illustrations of the posterior petrosal approach. A single bone flap is constructed spanning the middle and posterior cranial fossae. After the mastoidectomy and skeletonization of the sigmoid sinus, the presigmoid dura mater is opened and connected with the middle fossa dural opening across the superior petrosal sinus. The tentorium is cut to a point posterior to the trochlear nerve entrance.

Illustration depicting the exposure provided by the posterior petrosal approach. The sigmoid sinus is released by cutting the superior petrosal sinus and tentorium and is mobilized posteriorly into the area provided by the posterior fossa craniotomy.

The skin incision is similar to that described for the posterior petrosal approach. The anterior limb of the incision can be carried up to the midline to allow the skin flap to be reflected anteriorly.[12] The superficial temporal artery is preserved on the muscle layer. The skin is reflected anteriorly along with the temporal fascia to preserve the frontal branch of the facial nerve. The zygomatic arch is cut anteriorly and posteriorly and the temporalis muscle is reflected inferiorly. The bone flap is similar to the posterior petrosal flap, although it is extended farther anteriorly along the floor of the middle fossa and crosses the sphenoid wing (Fig. 5). The mastoid is drilled to skeletonize the labyrinth and the petrous apex is also drilled (Fig. 1C). The dura mater is opened in a similar fashion to the description of the posterior petrosal approach, but the incision is extended farther anteriorly along the floor of the middle fossa. The dura mater along the floor of the temporal fossa can be connected with a dural incision along the sphenoid wing to expose the sylvian fissure as well. The tentorium is incised anteriorly to the incisura posterior to the trochlear nerve insertion, and is connected with a tentorial cut paralleling the superior petrosal sinus from the posterior direction (Fig. 6). With this exposure, the tumor can be approached through the petrous bone anterior and posterior to the labyrinth and middle ear apparatus.

Illustration of the combined petrosal approach. The temporalis muscle is reflected anteriorly and inferiorly. The bone flap is similar to the one made for the posterior petrosal exposure, although it extends farther anteriorly to the sphenoid wing to allow resection of the petrous apex.

Illustration of the exposure provided by the combined petrosal approach. A wide view is available after resection of the petrous apex and retrolabyrinthine petrous bone. CN = cranial nerve; SS = sigmoid sinus.

The skin incision is similar to the combined petrosal approach. As the skin is reflected anteriorly, the external auditory canal is sectioned and closed in a blind sac.[2] The mastoidectomy is performed, followed by a labyrinthectomy. The facial nerve is then skeletonized along its course through the temporal bone and is left within a thin bone canal for protection. The tympanic membrane and inner earossicles are resected. The petrous apex and cochlea are then drilled to complete the petrosectomy (Fig. 1D). This approach allows unobstructed lateral visualization of the petroclival, clival, and cavernous sinus regions (Fig. 7).

Illustration of the exposure provided by a complete petrosectomy. The facial nerve is skeletonized throughout its course in the temporal bone.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....