方向交代性眼振—小脳橋角部髄膜腫に随伴し，腫瘍摘出により消失した方向交代性眼振の1症例

Nystagmus Alternance Disappeared after Removal of Meningioma in the Cerebello-pontine Angle: A case Report

　I．はじめに

　交代性眼振は，先天性眼振をはじめ，頭部外傷，小脳障害，多発性硬化症など様々な疾患で報告されている。その発現機序にはいまだ不明な点が多いが，眼運動系の制御機構の解明に大きな示唆を与えるものとして興味をもたれている。

　我々は今回，小脳橋角部髄膜腫に，明所開眼正中視位にて，左右に方向が周期的に交代する眼振を認め，腫瘍摘出後，完全にこの眼振の消失をみた症例を経験したので，ここに報告し，その成因につき考察を加えた。

　A 57-year-old house wife with dizziness and gait disturbance distinctly showed nystagmus alternance in the first-eye-position with a periodic cycle of 30~60 seconds.

　Besides this, Vth, VII th and VIII th cranial nerve disorders and loss of right labyrinth functin which accompanied with ipsilateral cerebellar signs were found preoperatively.

　This nystagmus completely disappeared after removal of a large meningioma in the right cerebellopontine angle. It was concluded that the causal area of the nystagmus might exist in the compressed area by this tumor. And a bibliographical discussion was made.