脳血管撮影における未破裂脳動脈瘤の検出率

Angiographical Frequency of Unruptured Incidental Intracranial Aneurysms

I．はじめに

　破裂脳動脈瘤によるクモ膜下出血には予後不良例も多く，未破裂脳動脈瘤の発見，治療は予防医学として重要である．CT，MRIなど侵襲の少ない検査法の進歩により，未破裂脳動脈瘤の検出が注目され，MR血管撮影によるスクリーニングが行われ始めている．しかしながらスクリーニングの対象を選ぶ上で重要と考えられる未破裂脳動脈瘤の危険因子については未だに明らかではない．脳血管撮影は破裂脳動脈瘤の確定診断に必須の検査ではあるが，侵襲が大きく，適応となる疾患は減少傾向にある．当院でも同様に脳血管撮影の施行件数は減少しているが，一昨年までは年間百数十例に及んでいた．この蓄積を基に未破裂脳動脈瘤の検出率，危険因子について検討したので報告する．

We reviewed cerebral angiograms studied between May 1985 and December 1992 focusing on unruptured incidental intracranial aneurysms.

In a total of 605 cases of cerebral angiograms except for patients with SAH, 43 patients (7.1%) were found to have unruptured aneurysms. In the 72 patients with headache, 11 patients (15.3%) were found to have un-ruptured aneurysms. This high frequency of unruptured aneurysms in headache patients is significant as a fac-tor showing that headache may be due to unruptured aneurysms.

The result of this observation is that as a screening study for headache patients, cerebral angiography may be required in spite of the invasive and high-risk method. But we think that MR angiography is, at pre-sent, a useful screening study only for detecting cere-bral aneurysms with a diameter of over 5mm, and which are considered to need an operation.