ABR audiometry in the diagnosis of cerebellopontine angle tumors.

Auditory brain-stem responses (ABR) examination with simultaneous lobe-vertex (L-V) and membrane-vertex cm-v) recording was performed in 34 ears with cerebellopontine angle tumors. The detectability of wave I was better in M-V recording than in L-V recording, whereas L-V recording exhibited better detectability of wave V. ABR waveforms were classified into three groups, and the relations between the waveforms and the size of tumor or the degree of hearing loss were analyzed. Positive finding in ABR were obtained in 25 out of 34 ears in the present study. It was stressed that this dual recording in ABR was extremely useful in the diagnosis of cerebellopontine angle tumors.