Vestibular schwannoma (CT) (1)

(A) Axial, enhanced image at the level of the cerebellopontine angle, demonstrating a large, diffusely enhancing tumor centered over the internal auditory canal. The mass extends through the porus acusticus into the internal enlarged auditory canal. Note the compression of the nearby pons and cerebellum. There is little, if any, associated edema within the brain, suggesting that compression developed slowly. (B) Axial image using bone windows and air contrast, demonstrating a small, intracanalicular tumor within the internal auditory canal. (Contributed by Dr. Herbert Newton.)