A posterolateral approach to the skull base: the petro-occipital transsigmoid approach.

This posterolateral approach is directed to the petro-occipital skull base and is a combination of a suboccipital craniotomy, with an inferoposterior petrosectomy. The areas exposed are the jugular foramen, occipital condyle, lower clivus to the midline, petrous apex, tympanic cavity, the vertical portion of the intrapetrous carotid artery below the level of the eustachian tube, cerebellopontine angle, the jugulocarotid space in the upper neck. We evaluated 45 cases as follows: 13 chemodectomas, 14 lower cranial nerve schwannomas, 10 meningiomas, and 8 other lesions. The approach is indicated for extra-, intra-, and transdural lesions of the jugular foramen area. The transdural lesions could be extirpated in a single procedure without cerebrospinal fluid leak. This, in addition to preservation of the facial nerve, middle and inner ear functions, constituted the main advantages of this approach. Lower cranial nerve deficit formed the major morbidity in the present series and is still an unsolved problem in such cases.