聴神経腫瘍におけるABRの意義

The Diagnostic Value of ABR in Acoustic Neuroma

I．はじめに

　Auditory Brainstem Responsc（以下ABR）は現在聴神経腫瘍の診断に必要不可欠の機能検査となったといって過言ではない。それは本検査が従来より用いられてきた検査手段より―とくに早期の聴神経腫瘍に対して―きわめてすぐれた診断価値を有するためである。

　本検査が臨床に応用されるようになって以来，多くの施設でその有用性が報告されており，おおかたの評価が確立されつつある状況にある。

　The diagnostic evaluation of ABR was studied on 28 ears (20 patients) of acoustic neuroma, which were surgically confirmed. The results arefollowings.

　1) ABRs of acoustic neuromas could be devided into 3 types : (a) clear recognizable Wave I with indistinct or absent succeeding waves, (b) no response, (c) ABR with prolonged latency of Wave 1 .

　2) Type (a) and type (b) have been proved to be useful indicators for diagnosis of the acoustic neuroma.

　3) Both Waves I and V could be obtained in a relatively few cases, in this study, so the study of type (c) revealed that the prolonged latency of Wave V was the most appropriate parameter among the I - V latency difference, latency differences of Wave V between affected and non-affected ears and I - V difference between right and left ears.

　4) Relative to 3) the diagnostic criteria of Wave V latency prolongation were determined in the stand point of differential diagnosis between retrocochlear and cochlear lesions.

　5) Summarizing the above mentioned, it can be concluded that ABR is an excellent tool for diagnosis of acoustic neuroma.