Combined petrosal approach to petroclival meningiomas

OBJECTIVE: To study the use and advantages of combining the posterior petrosal approach with the anterior petrosal approach to petroclival meningiomas. METHODS: Seven cases of petroclival meningiomas operated on via the combined petrosal approach were retrospectively analyzed. The basis on which this approach was selected was assessed, as were its benefits and risks. RESULTS: Gross total resection was achieved in five of the seven patients. No mortality or decrease in Karnofsky performance score was observed at the time of the last follow-up examination. Six of the seven patients had serviceable hearing before the operation. Only one patient lost hearing after the operation, and this hearing loss occurred in only one ear. Before the operation, six patients were House-Brackmann facial nerve function Grade I, and one patient was Grade II to III. At the last follow-up examination, facial nerve function was Grade I in five patients, Grade II in one patient, and Grade V in one patient. Tumors in all patients involved the cavernous sinus, Meckel's cave, petroclival junction, and middle clivus. All patients possessed a large posterior fossa component of tumor measuring an average of 3.6 x 3.5 x 4.2 cm. In four patients, the tumor was attached for the entire width of the clivus to the contralateral petroclival junction. Four patients displayed central brainstem compression. Four patients displayed bony changes at the petrous apex. All patients displayed total or partial encasement of the vertebrobasilar artery and its major branches. CONCLUSION: The combined petrosal approach should be considered for patients who have a large petroclival meningioma and serviceable hearing. This approach enhances petroclival exposure and the degree of tumor resection, especially in the area of the petroclival junction, middle clivus, apical petrous bone, posterior cavernous sinus, and Meckel's cave. The combined petrosal approach also allows better visualization of the contralateral side and the ventral brainstem, which facilitates safe dissection of the tumor from the brainstem, the basilar artery, and the perforators. If a patient has an early draining bridging vein to the tentorial sinus (before it reaches the transverse-sigmoid junction) or a prominent sigmoid sinus and jugular bulb, the combined petrosal approach provides significant working space.