Temporal Bone Resection

This procedure is employed for malignant disease of the external auditory canal and middle-ear cleft (this is most common squa-mous cell carcinoma). If the tumor has not involved more medial structures, a lateral temporal bone resection is employed (see Fig. 15.6) that removes the ear canal en bloc, with the tympanic membrane and lateral ossicles. A parotidectomy and/or neck dissection often supplements this procedure.

Surgical Steps

At the beginning of this procedure, the ear canal is transected and closed. This closure is different from that used during lateral skull base surgery - simply sewing the tragal skin to the conchal margin permits resection of the skin of the entire ear canal.

After transection of the cartilaginous ear canal just beneath the meatus, an intact canal wall mastoidectomy is performed. The middle ear is opened by performing a posterior tympanotomy (opening into the middle ear from the mastoid between the upper vertical portion of the facial nerve and the chorda tympani). The incus is then removed and the descending portion of the facial nerve is skeletonized.

In order to isolate the ear canal as an en bloc specimen, bone must be removed from 360°

Fig. 15.6. Anatomy of the temporal bone in the coronal plane, showing the extent of the resection in a lateral temporal bone resection (outlined by the dotted line) and total petrosectomy (outlined by the dashed line).

around the ear canal. The posterior tympanotomy is extended to the posterior and inferior aspects of the middle ear. The front of the mastoid is removed between the inferior margin of the bony ear canal and the stylomastoid foramen. Superiorly, the root of zygoma and the posterior aspect of the glenoid fossa are removed.

Working between the floor of the middle cranial fossa and the roof of the ear canal, the root of zygoma is drilled away until the anterior middle ear has been opened into the glenoid fossa. After the ear canal has been isolated from above, behind and below, it remains attached only anteriorly. This bony attachment can then be "cracked" using an osteotome and the specimen removed. This specimen includes both the cartilaginous and bony ear canal, together with the tympanic membrane with the malleus attached.

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