A Case with Unilateral Fluctuating Hearing Loss Difficult to Diagnose

A 47-year-old male at first examination to have any one of sudden deafness of the right ear, or gouty inner ear disorder, however, was thought Ménière's disease because of the fluctuating hearing loss these diseases were denied. It was finally confirmed that an aneurysma of the right anterior cerebellar artery by vertebral angiography and this was thought to cause the fluctuating hearing loss. After operation the hearing loss was improved and the hearing remained stationary at 36dB on an average. Vertiginous attack, tinnitus, dull pain of the right head and spastic sensation of the right face also disappeared. Electrocochleographic study showed a steeper input-output function curve of AP on 24 days after the initial examination. Even when the pure tone audiogram showed no response, CM with low voltage was recorded but no AP was recorded. These findings seemed to suggest that the cochlear nerve would be more affected than the cochlear hair cells. The polarity of SP maintained a negative dominant deflection. After the operation, AP wave form became broard. This finding was similar to the broad AP recorded in cases of tumor in the posteriocranial fossa.