The Neuro-otologic Evaluation

EIGHTH nerve symptoms, with rare exceptions, are the first indication of a developing acoustic neuroma. A high index of suspicion combined with a thorough neuro-otologic evaluation should make it possible to diagnose this tumor when it is relatively small; hopefully, when still localized to the internal auditory canal. The purpose of this section of the monograph is to describe the neuro-otologic evaluation and discuss the symptoms produced by this histologically benign but clinically malignant tumor. Symptomatology An acoustic tumor produces symptoms and findings by pressure on both blood vessels and nerve tissue and, when quite large, by blocking the cerebrospinal fluid (CSF) absorption mechanism. When resulting from interference with blood supply, these symptoms and findings may be of dramatically sudden onset, simulating a cochlear or inner ear problem, or basilar vertebral insufficiency. As such, they may fluctuate or apparently respond to medical treatment. The symptoms resulting from pressure on neural