The system of the modified transcochlear approaches to the petroclival area and the prepontine cistern.

Between June 1986 and June 1993 46 different tumors (27 extradural and 19 intradural) located in the petroclival area and/or prepontine cistern have been operated on at The Gruppo Otologico Piacenza and the ENT Department of Bergamo, Italy using a modification of the transcochlear approach. Total tumor removal was obtained in all cases. Complications occurred in eight patients. One patient died due to infarction of the brain stem. The system of modified transcochlear approaches conceived for the removal of various intradural and extradural tumors is presented. This approach, together with its modifications, is the major operative access to the central skull base and clivus among a series of lateral approaches described in the literature. The basilar surgical technique (type A) and its modifications (types B, C, D) are described in detail, and five different, illustrative cases are presented. Indications, limits, results, and complications related to the approach are discussed.