Abstract
Pathophysiology of hearing impairment in acoustic neuromas is still controversial. We conducted electrocochleographical (ECoG) evaluation on hearing loss in 34 acoustic neuromas, and comparison was made between the ECoG findings and their sizes on MR image, and pure tone audiogram (PTA). The disparity was noticed in the threshold of PTA and detective threshold of action potential (AP) and cochlear microphonics (CM), and the threshold of the PTA was worse than the threshold of AP and CM. The disparity was found to be correlated well with the size of the tumor. There was no correlation between the size and the extent of cochlear damage which presumed by the amplitude and detective threshold of AP and CM. These results revealed that ECoG is useful for evaluating cochlear and retrocochlear hearing impairment in acoustic neuromas.
