Intralabyrinthine Acoustic Neurinomas

Abstract

Two temporal bones are presented that contain acoustic neurinomas unsuspected during life and anatomically limited to the perilymphatic labyrinth. One tumor occupies the modiolus and scala tympani of the cochlea without involving the internal auditory canal. The other tumor originates in the fibers below the utricular macula and spares both the macula and the lamina cribrosa. Neither case demonstrates bone destruction. Even if these tumors had been suspected during life, tomograms would have been normal and the posterior fossa myelogram would have shown complete filling of the internal auditory canal.