Posterior Petrosectomyneurotologist

Forward Head Posture Fix

Forward Head Posture Fix

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After completion of the cervical exposure, our neurotologist performs the posterior petrosectomy. This is performed under the operating microscope with continuous irrigation and a variety of cutting and diamond bits on a high-speed drill.

Description

Transcanal Postauricular Postauricular Postauricular

Traditional skull base Traditional skull base Modified infratemporal Modified and/or extended infratemporal

Figure 82-3 Positioning for the craniocervical approach. The patient is placed supine with the head in three-point fixation. The head is rotated to the contralateral side and a crescent-shaped skin incision is made from above the ear, passing 4 cm behind the mastoid tip, and down the anterior border of the sternocleidomastoid muscle to the cricoid cartilage. (Reprinted with permission from Tew JM, van Lov-eren HR, Keller JT: Atlas of Operative Microneurosurgery, Volume II. WB Saunders. In press.)

Figure 82-3 Positioning for the craniocervical approach. The patient is placed supine with the head in three-point fixation. The head is rotated to the contralateral side and a crescent-shaped skin incision is made from above the ear, passing 4 cm behind the mastoid tip, and down the anterior border of the sternocleidomastoid muscle to the cricoid cartilage. (Reprinted with permission from Tew JM, van Lov-eren HR, Keller JT: Atlas of Operative Microneurosurgery, Volume II. WB Saunders. In press.)

Initially the mastoid is decorticated from its tip inferiorly to the supramastoid crest (floor of the middle fossa) superiorly and from the posterior wall of the external auditory canal anteriorly to the sigmoid plate over the sigmoid sinus posteriorly. Resection of mastoid air cells exposes the cortical bony plates of the sigmoid sinus, temporal plate, canalicular plate, and sin-odural angle. As the air cells are removed, the antrum is entered posterior and deep to the spine of Henle in Macewen's triangle. The lateral process of the incus and the lateral semicircular canal can be identified through the antrum. Exposure of the digastric ridge, the posteroinferior cortical indentation of the mastoid tip produced by the digastric muscle, serves as a landmark to the stylomastoid foramen and the distal end of the fallopian canal. The lateral, posterior, and superior semicircular canals are then further exposed. The remaining retrofacial air cells are removed to skeletonize the facial nerve in the fallopian canal from its external genu at the inferior edge of the lateral semicircular canal to the stylomastoid foramen. The chorda tympani is also identified at its origin from the vertical segment of the facial nerve. The sigmoid plate is further decorticated, and ultimately the thin shell of bone over the sigmoid sinus is removed. This dissection is car ried inferiorly to expose the jugular bulb. Exposing the middle and posterior fossa dura and the intervening superior petrosal sinus reveals the superior semicircular canal (Fig. 82-4B). For patients with irreversible hearing loss a labyrinthectomy may be performed to expand the exposure.

Management of the facial nerve is an important component of surgical approaches to the jugular foramen.78 Pensak and Jack-ler79 suggested three options for facial nerve management, depending on the extent of tumor: (1) intact canal wall without facial nerve rerouting, (2) canal wall-down without facial nerve rerouting, (3) canal wall-down with anterior facial nerve rerouting. The first option maintains the physiologic structure of the ear canal and middle ear to preserve auditory functions, but is limited in its anterior exposure. The use of the canal wall-down approach without facial nerve rerouting is indicated when the ear canal or middle ear is extensively involved by tumor. Extended retrofacial exposure can be performed after transection of the chorda tympani with creation of a fallopian bridge (circumferential skeletonization of the fallopian canal) (Fig. 82-4C). With the fallopian bridge technique, tumors can be dissected posterior, lateral, and medial to the ICA after drilling of the carotid ridge. Preserving the normal anatomic position of the facial nerve

Figure 82-4 (A) The sternocleidomastoid muscle (SCM) is retracted laterally and dissection continues through the cervical fascia to the carotid sheath. The common facial vein is ligated and the hypoglossal nerve is identified as it crosses the carotid bifurcation. The ICA (internal carotid artery), ECA (external carotid artery), and IJV (internal jugular vein) are isolated with color-coded Silastic loops.

(B) The skin and muscles over the mas-toid area are reflected and the external ear canal is transected and closed in three layers and oversewn with a periosteal flap. The standard mastoidectomy is expanded by removing bone anterior to the facial nerve, called the facial recess (triangle), and sacrificing the chorda tympani nerve.

(C) The posterior canal wall is thinned to eggshell thickness and removed (canal wall-down). The incus, malleus, and tympanic membrane are removed. Retrofacial air cells are removed with a high-speed drill, effectively creating a fallopian bridge containing the facial nerve. Bone of the mastoid tip is thinned and removed to the level of the digastric ridge. (Reprinted with permission from Tew et al.84)

increases the likelihood of normal postoperative facial nerve function. The third option with facial nerve rerouting, originally described by Fisch,77 is reserved for the infrequent tumor with extension anterior to the carotid genu. Mobilization of the mandible may also be necessary in this circumstance, if there is significant middle fossa and infratemporal extension.

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