Magendie孔膜様閉塞により生じた“disproportionately large，communicating fourth ventricle”の1例

“Disproportionately Large, Communicating Fourth Ventricle” due to Membranous Obstruction of Magendie's Foramen

I．はじめに

　第四脳室の著明な拡大を伴う全脳室系の拡大を認める症例は，1980年Scottiにより“disproportionately large，communicating fourth ventricle（DLCFV）”と提唱された．その原因は腫瘍，炎症，クモ膜嚢胞，Chiari mal—formation，クモ膜下出血など様々なものが考えられるが，今回われわれは，特に既往歴を認めず，Magendie孔の膜様閉塞にてDLCFVと考えられ，その膜様物を切除することにより治癒した1症例を経験したのでここに報告する．

A case of disproportionately large, communicating fourth ventricle (DLCFV) with the entire ventricular system dilated symmetrically due to membranous ob-struction of Magendie's foramen is reported. A 20-year-old female complained of headache and nausea. Slight papilledema was found in both eyes. CT scan and MRI showed that the entire ventricular system was dilated symmetrically, but we could not locate the cause of this disease, for example, tumor, arachnoid cyst, cerebellar malformation and so on. Although cinemode-MRI showed CSF pulsation as if CSF flowed through Magendie's foramen, we were not convinced that CSF flowed through it. We speculated that something ob-structed CSF flow at Magendie's or Luschka's foramen, so surgery was performed by suhoccipital craniectomy.As expected, a mombranous obstruction was found at Magendie's foramen. After excision of the membrane, all symptoms improved. Postoperative cinemode-MRI clearly demonstrated CSF flow through Magenclie's foramen.

Ventriculoperitoneal shunting is generally effective for DLCFV, but we do not consider it the optimal treatment. The cause of DLCFV must be confirmed by suboccipital craniectomy if evidence of NPH, mass le-sion or cerebellar malformation cannot be found any-where especially around Magendie's foramen.