Retrolabyrinthine surgery: anatomy and pathology.

Retrolabyrinthine surgery is done to expose the cerebellopontine angle directly through the ear. It is indicated when the hearing in the ear to be operated upon is useful. The surgical technique entails four steps: complete mastoidectomy, extended posterior exposure of the sigmoid sinus, exposure of the posterior fossa dura, and exposure of the cerebellopontine angle. Retrolabyrinthine exposure of the cerebellopontine angle is indicated in tic douloureux, atypical facial pain, and hemifacial spasm. Recently, this approach has been used for sectioning the vestibular nerve, exploration of the posterior fossa to obtain a diagnosis, subtotal resection of large cerebellopontine angle tumors, and for the treatment of other cranial nerve problems. The histopathologic findings in the temporal bones of two patients who underwent retrolabyrinthine removal of cerebellopontine angle masses were reviewed. In one, subtotal resection of an acoustic tumor was attempted to preserve hearing in the presence of a bilateral tumor, with no adverse effect on the middle or inner ear. In the second, retrolabyrinthine exploration of the cerebellopontine angle was done for primary cholesteatoma, and operative injury to the nonampullated end of the posterior semicircular canal was noted. Retrolabyrinthine subtotal resection of large acoustic tumors is advocated in bilateral cases and in elderly persons to delay the inevitable loss of hearing by decompression and partial removal of the tumor mass. In primary cholesteatoma of the cerebellopontine exploration may be indicated to obtain a definitive diagnosis before surgical extirpation of the disease is planned.