Acoustitc neuroma cases with normal hearing or radiologically normal internal auditory meatus

Among 85 cases with acoustic neuroma, we had five cases with normal hearing and another 5 cases which had radiologically normal internal auditory meatus. All cases with normal hearing had a history of cochleo-vestibular symptom and had enlarged internal auditory meatus. In addition, four cases had canal paraesis and abnormal auditory brain stem response. On the other hand, those who had radiologically normal internal auditory meatus had decerased hearing acuity in the lesion side ear, and four of 5 cases had canal paraesis. Thus a case with acoustic neuroma which has normal hearing could be detected by radiological examinations and audiological tests. Furthermore one should always keep in mind the possibility of acoustic neuroma which has hearing impairment along with canal paraesis.