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Cadaveric Dissection: Anterior Petrosal Approach

July 22, 2016


This is another short video discussing technique for the anterior petrosal approach. This is a cadaveric dissection. You can see the linear incision just anterior to the ear. The incision extends just slightly below the zygomatic arch. After the incision is completed, the temporalis muscle is also incised and reflected anteriorly. Blunt dissection may be used to preserve as many of the STA branches as possible. Here you can see the temporalis muscle with its fascia that is incised more posteriorly and then reflected anteriorly. This mobilization of the muscle moves it out of our way during the exposure of the posterior aspect of the bone. Burr hole is placed just about the level of the root of zygoma or posteriorly. Temporal craniotomy is completed as low as possible. I use the level of the zygomatic arch as the level of the middle fossa floor. As you know, the floor slopes inferiorly in the posterior to anterior direction. Now, the dura has been elevated. Some of the landmarks have been marked. Here you can see the foramen spinosum, internal auditory canal, arcuate eminence. Here, would be the route of the internal carotid artery. And here is the petrous apex that has to be resected to provide a corridor from the middle fossa into the posterior fossa. And foramen spinosum is demonstrated. Third division of the trigeminal nerve is traveling in this location. Bone removal is confined just medial to the area of the cochlea that will be approximately here. Lumbar drain is used during surgery to decompress the temporal lobe effectively, allowing mobilization of the dura without significant temporal lobe retraction. We'll go ahead and use an air drill to be able to complete the petrous apex bone area resection. Aerosols may be encountered in this area. Anatomical location of the internal auditory canal and the internal carotid artery, as well as the cochlea are important for guiding safe and effective resection of the petrous apex and maximizing the operative corridor for removal of upper petroclival meningiomas. The bone can be quite thick. The bone is thinned down, and the thin shell of bone eventually removed using curates. You can see the more lateral part of the clivus, the dura over the middle fossa. Now linear incision is created over them in a fossa and connected to an incision within the posterior fossa. Obviously the trigeminal nerve that passes through the tentorium has to be carefully protected at this juncture. Thank you.

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