抄録
In 25 patients with confirmed acoustic and cerebellopontine angle tumours seen in our clinic from 1979 to 1983, the auditory brainstem responses (ABR) were evaluated in relation to the ABR patterns stimulated on affected and non affected ears by means of click sounds. The results are as follows; 1) The ABR patterns obtained from the affected ear stimulation could be separated into 3 types. Type A showed a prolongation of the I-II inter peak latency (IPL) or I-V IPL. Type B showed the presence of wave I only or waves I and II. Type C showed no response. 2) The ABR patterns obtained from non tumour ear stimulation could be separated into 3 types. Type 1 showed the normal range of I-V IPL. Type 2 showed a prolongation of III-V IPL. Type 3, the wave V was still poorly defined or wave V was absent. The abnormalities were observed in 67% of the subjects. 3) The size of tumours in types 2 and 3 were larger than 3cm. as measured on the CT scans. The different ABR components in the affected ear, as compared with findings in the non affected ear provide pertinent information which leads to an early diagnosis of acoustic and cerebellopontine angle tumours. The relationship between the size and location of tumour can also be defined.
