Auditory brain-stem evoked responses in cerebellopontile angle tumors.

Large acoustic or nonacoustic cerebellopontile angle tumors cause severe to total hearing loss on the same side. Such a tumor can also cause hearing loss on the opposite side by pressure effect on the brain stem. This was observed in 23 patients with large tumors that were surgically treated. Their computed tomographic scans and surgical findings supported the auditory brain-stem evoked potential changes noted in this study. Early removal of such a tumor is essential to prevent any possible hearing loss on the opposite side that may be produced by the tumor.