第4脳室開口部膜様閉塞による水頭症

Hydrocephalus due to Membranous Obstruction of the Fourth Ventricle Aperture

I．はじめに

　第4脳室開口部の閉塞による水頭症の原因には，腫瘍や炎症，Dandy-Walker奇形など種々のものを挙げることができるが，既往歴や術中所見に明らかな原因疾患がみられず，Magendie孔部での膜様閉塞による水頭症を3例経験した．過去に同様の報告^1,4）は少なく，その診断ならびに病因について検討を加えたので報告する．

Three cases of hydrocephalus due to membranous obstruction of the fourth ventricle aperture are reported. Patient's age was 4, 34 and 68 years old and they complained of slowly progressive cerebellar ataxia, gait disturbance and other hydrocephalic symptoms.

CT scan revealed symmetrical dilatation of lateral ventricles, and, especially, the fourth ventricle aperture was confirmed by ventriculography or metrizamide CT cisternography.

Suboccipital craniectomy was performed in all cases and cerebellum was of normal shape and semilucent membrane was found obliterating the foramen of Magendie.