Effects of brain stem lesions on cochlear function: mechanism of hearing improvement after removal of a brain stem tumor.

EOAEs are well correlated with changes of hearing sensitivity during the clinical course of brain stem lesions, as shown in this case study. They may serve as sensitive indicators to evaluate the possible effects of a brain stem lesion on cochlear function and monitor the attempted preservation of hearing during CPA or brain stem surgeries. It is thereby suggested that EOAEs should be included in an audiologic test battery in a differential diagnosis of retrocochlear lesions.