Extended retrolabyrinthine transtentorial approach to petroclival lesions. In this communication, an extension of the retrolabyrinthine approach that has permitted safe, effective access to the petrous tip and clivus is presented. The basic technique involved complete mastoidectomy, preservation of the middle and inner ear structures, removal of the sigmoid and middle fossa plates, middle and posterior fossa craniotomies, ligation of the superior petrosal sinus, and division of the tentorium. Nine cases that exemplified the versatility of this approach constituted the basis of this paper: 2 cholesteatomas, 2 basilar artery aneurysms, 2 chordomas, and 3 meningiomas. The indications for, and complications of, this method have been discussed. 