小脳橋角部腫瘍の臨床的，神経耳科学的観察—聴神経腫瘍とその他の腫瘍との比較

CLINICAL AND NEUROTOLOGICAL STUDIES IN CEREBELLO-PONTINE ANGLE TUMOR

　Ⅰ．緒言

　小脳橋角部の腫瘍は第Ⅷ脳神経から発生した神経腫（acoustic tumor以下AT）が大部分をしめ，A. G. Revilla，佐野によれば，それ以外に約10％前後の比率で真珠腫，髄膜腫，第Ⅷ脳神経以外の神経腫，神経膠腫などのいわゆる非-AT腫瘍が発生するという。それ故に実際にわれわれがATと診断する場合にも，Cushingのいう非定型的のATを含めて，これら非-AT腫瘍との鑑別は臨床上重要である。そこでわれわれは臨床的に神経耳科学的所見を中心にして最終診断した症例のうち，脳外科の手術所見や病理組織検査の結果，ATでないことが明らかとなつた症例を観察症例とした。すなわち小脳橋角部に発生する腫瘍には，ATを除いて，どのようなものが実際にみられ，しかも，これらの腫瘍は神経耳科学的にATとどのような鑑別点をもつかを検討したのでここに報告する。

　Nine cases of lesion in the cerebellopontine angle, excluding acoustic tumor, seen in the recent 2 years are reported. These cases consisted of 2 without any tumor, 3 of cholesteatoma, 2 of trigeminal neurinoma and 1 each of meningioma and bilateral neurofibroma. The diagnosis of these cases was made in each by Operative findings after craniotomy and histological tissue examination of the specimens removed. Clinical symptoms of these cases are compared with those clisted by acoustic tumors. Following neurotological observations are made:

　1) The caloric test showed a normal response in all cases that were free of tumor and in some cases of trigeminal neurinoma. The other cases showed almost no response.

　2) The audiometry was also normal in all cases without any tumor and in some cases of cholesteatoma and trigeminal neurinoma.

　3) The nystagmus was shown to be the most remarkable objective findings both in the direction and the character in all cases considered as tumor free. But, in cases of bilateral neurofibroma it was manifested very poorly. Optokinetic pattern test (OKP) and eye tracking test (ETT) showed a normal response in all tumor-free cases.

　4) The differential diagnosis of acoustic tumor and that of cholesteatoma and meningioma appeared to be too difficult a process at the present stage of knowledge. However, the analysis of their subjective symptoms would be of some help to the solution.