Surgical exposure of the facial nerve indications and techniques

Lesions producing facial nerve palsy may occur within the temporal bone anywhere between the internal auditory canal and the stylomastoid foramen. Surgical exposure of this nerve may be necessary for decompression, grafting, rerouting, or removal of such lesions as acoustic tumour, meningioma, facial nerve neuroma, and cholesteatoma. Contemporary surgical exposure of the facial nerve has as its aim adequate exposure of the facial nerve at any point in its course, with preservation of hearing and vestibular function, without further injury to the facial nerve and the necessity for producing a mastoid cavity. When hearing and balance function are present, the transcanal-transtympanic approach to the horizontal segment of the facial nerve offers limited access to the facial nerve in its tympanic course. Wider exposure is obtained by postauricular transmastoid exposure of the tympanic and mastoid portions of the facial nerve. The middle fossa approach to the facial nerve offers access to the internal auditory canal and labyrinthine portions of the nerve, whereas the retrolabyrinthine approach offers access to the facial nerve in the posterior fossa. Total facial nerve exposure with preservation of hearing and balance function is obtained by the combined transmastoid and middle cranial fossa approach. In individuals who have lost all function of hearing and balance, the postauricular translabyrinthine approach offers total exposure of the facial nerve within the temporal bone and posterior fossa. The aim of this discussion was to present in succinct fashion a systematized approach to surgical exposure of the facial nerve within the temporal bone and posterior fossa.