疼痛発症の解離性椎骨および中大脳動脈瘤の合併例

A Middle Cerebral Artery Dissecting Aneurysm Manifesting Solely with Pain,Following a Vertebral Artery Dissecting Aneurysm

Ⅰ．は じ め に

　頭蓋内解離性動脈瘤の多くは椎骨脳底動脈系に発生し，その約10％が多発するとされている．しかし，その多くは両側の椎骨動脈に発生したものであり¹⁹⁾，椎骨脳底動脈系と内頸動脈系の両方に発生することは極めて稀である．

　解離性動脈瘤の病態としては，はじめに解離に伴う頭痛が出現し，その後解離が外膜まで進むと出血を来し，壁内血腫により内腔が閉塞すると虚血症状を呈する．しかし，最近の検査機器の発達に伴い，頭痛の段階で診断される症例も増えてきており，その経過が注目されている¹⁸⁾．

　今回われわれは，解離に伴う頭痛の段階で診断された解離性椎骨動脈瘤の経過観察中に，新たに解離性中大脳動脈瘤を併発した稀な1例を経験したので，文献的考察を加えて報告する．

　A 41-year-old male had presented with severe neck pain and was diagnosed as having a left vertebral artery (VA) dissecting aneurysm. During the observation period,he suddenly suffered from a pain on his left temple. MR imaging revealed neither SAH nor cerebral infarction. MR angiography,computed tomographic (CT) angiography and cerebral angiography showed fusiform dilatation of the M1 portion of the left middle cerebral artery (MCA) which had been normal in the former study. The abnormality of the left MCA normalized on both MR and CT angiography 6 months after the second onset. Because of the chronological change of radiological findings compatible with the symptom,we diagnosed the second episode as a MCA dissecting aneurysm manifesting with isolated pain. Among the previous forty-four MCA dissecting aneurysms,all but one case presented with hemorrhagic or ischemic event. In addition,this is the only case of multiple dissecting aneurysms of VA and MCA manifesting with isolated pain.