聽神経腫瘍症状を呈したる蜘蛛膜嚢腫の1例

　緒言脳の真性腫瘍以外の疾患が，屡々脳腫瘍類似の症候を呈することのあるのは，1876年Hughlings, Jackonが軽度の脳の充血した以外に何等脳腫瘍らしきものを認めなかつたのに，著明な脳腫瘍症状を示した1例を報告して以来，大いに注目せられて来た．

　斯かるものを一括して，所謂偽腫瘍といわれているがその中には蜘蛛膜炎，蜘蛛膜嚢腫，脳水腫，出血性脳炎，諸種脳脊髄膜炎，脳軟化症，脳血管硬化症，硬膜下血腫，静脈洞血栓症，Schilder氏症，内頸動脈動肱瘤，脳炎，脳黴毒，脳膿瘍，多発性硬化症，脳結核等多くの疾患が挙げられ，その内近年殊に蜘蛛膜炎及び蜘蛛膜嚢腫が最も注目されている．

TAKAHARA AND ARAKAWA report a case of arachnoid cyst and point out the essentials upon which differential diagnosis of the eighth nerve tumor, inflammation of arachnoid mempranes and arachoid cyst are to be made. The patient was a man aged 43 who complained of vertigo which became progressively worse and hearing impaire-ments accompanied with marked tinnitus. With tena-tive diagnosis of suspected eighth nerve tumor operation on the head was performed. A cyst the size of thumb-head was found at the cerebellar pontine angle completely engulfirig the eighth nerve in its growth. After this nerve was freed from pressure without the patient no longer complained of dizziness and vestibular functions became nor-mat: also, was somewhat improved.