Abstract
Electrocochleography was performed on twelve patients with acoustic neurinoma. Recordings were made with transtympanic needle electrode. Compound cochlear nerve action potential (AP) showed a lower threshold compared with that of the pure tone audiogram, and a well defined cochlear microphonic potential was observed. Some patients showed a well defined AP potential, although totally deaf. The AP with intense sound stimulation showed a low potential and/or a shallow input-output function slope. The above findings seem to result from retro-cochlear hearing impairment.
