Progressive hearing loss in intracochlear schwannoma.

Intralabyrinthine schwannomas are rare tumors. It is difficult to diagnose them, and their hearing disturbance has not been sufficiently elucidated. Recently, however, the development of the imaging technology enables the diagnosis of intracochlear schwannoma before operation. We experienced a case of intracochlear schwannoma diagnosed with mild hearing loss. Pure tone audiometry (PTA) showed hearing loss at mid-frequency, with a mean threshold of 33.3 dB. Magnetic resonance imaging (MRI) revealed an abnormal lesion in the cochlea. Finally, PTA showed profound deafness and MRI revealed invasion of the schwannoma into the fundus of the internal auditory canal. Considering the progress and the results of audiometric examinations, hearing disturbance by intracochlear schwannoma is investigated in this report.