Surgical Technique

Because the exact site and extent of lesion and the method of repair are difficult to anticipate, the patient should be prepped and draped for middle fossa craniotomy (if hearing is good), mastoidect-omy, parotidectomy, great auricular nerve graft, and even hypoglossal nerve dissection — virtually the entire side of the head and neck. Extensive exploration at multiple sites and mobilization or nerve grafting can require considerable time; most patients should have a Foley catheter placed that can be removed at the end of the procedure. A facial nerve monitor/stimulator is unnecessary because the nerve will not respond, since several days or longer often are required to evaluate and stabilize neurolo-

Tympanic Sinus
FIGURE 18 —1 (A) Facial recess approach to the facial nerve. (B) Skeletonized fallopian canal and internal auditory canal (IAC). MFD, middle fossa dura; PFD, posterior fossa dura; SS, sigmoid sinus; CT, chorda tympani; VII, facial nerve.
Chorda Tympani Nerve

FIGURE 18-2 Middle cranial fossa approach to the facial nerve. (A) Orientation. (B) Close-up view. GSPN, greater superficial petrosal nerve; Gg, geniculate ganglion; M, malleus; I, incus; S, stapes; VII, facial nerve; SVN, superior vestibular nerve; IVN, inferior vestibular nerve; ICA, internal carotid artery; C, cochlea; AE, arcuate eminence.

FIGURE 18-2 Middle cranial fossa approach to the facial nerve. (A) Orientation. (B) Close-up view. GSPN, greater superficial petrosal nerve; Gg, geniculate ganglion; M, malleus; I, incus; S, stapes; VII, facial nerve; SVN, superior vestibular nerve; IVN, inferior vestibular nerve; ICA, internal carotid artery; C, cochlea; AE, arcuate eminence.

gic and other injuries. We routinely ask a neurosurgeon and a head and neck surgeon to stand by in case they are needed.

A mastoidectomy is performed first, and the nerve from the geniculate to the stylomastoid foramen is examined through the facial recess (Fig. 18-1). If perigeniculate trauma extends proximally and hearing is good, a middle fossa craniotomy is performed and the canalicular and labyrinthine segments are examined (Fig. 18-2). If hearing is poor, a translabyrinthine approach suffices (Fig. 18-3). If the nerve is sheared off at the stylomastoid foramen, the mastoid tip is removed and a superficial parotidectomy performed. By this time the traumatized nerve has been decompressed and bone spicules have been removed.

If the nerve is transected, the surgeon then decides whether proximal and distal segments can be mobilized for primary anastomosis; otherwise, a great auricular nerve graft is obtained. An imaginary line drawn inferior and perpendicular to a second line that connects the mastoid tip and angle of the mandible will lie in the location and direction of this nerve (Fig. 18-4). A separate incision is used to obtain a 2- or 3-cm graft, as needed. The traumatized ends of the facial nerve are freshened, and two or three 9-0 or 10-0 monofilament sutures are used for anastomosis. If the injury lies in the tympanic fallopian canal or labyrinthine canal, the graft can be laid in the canal in an S shape and held against the facial nerve ends with connective tissue or fibrin glue (Fig. 18-5). If the defect is large and suturing in the cerebellopontine angle is not possible, a hypo-glossal-facial anastomosis can be performed at the same time or as a separate procedure.

Nerve recovery following primary repair or grafting requires at least 3 months for injuries at the stylomastoid foramen, 6 months for the second genu, 9 months for the geniculate ganglion, and 12 months for the internal auditory canal. Depending on the estimated time for recovery, a gold weight can be placed in the upper eyelid at the time of nerve repair to assist eyelid closure. The weight is removed when recovery is complete.

Drains are left in any parotid and neck incisions and a large bulky dressing is applied to the craniotomy and mastoid sites. Drains are removed when 24-hour drainage is less than 30 cc and the dressing is removed at 3 days or sooner if the patient is ready for discharge.

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