脳動静脈奇形における還流静脈系の狭窄・閉塞について

An Occlusion and Stenosis of the Venous Drainage System in Cerebral AVMs : Angiographical Investigation

　脳動静脈奇形（AVM）における還流静脈の狭窄あるいは閉塞について血管撮影から検討した。対象は，当施設において診断した脳AVM51例で，そのうち8例にAVMからの還流静脈の狭窄や閉塞を認めた。そのうちdural AVMが2例，mixed pial-dural AVMは1例，pial AVMは5例であった。狭窄または閉塞部位は，vein of Galenと直静脈洞移行部が3例，直静脈洞が2例，vein of Labbeと横静脈洞移行部が1例，上矢状静脈洞が1例，S状静脈洞が1例であった。これらの8例中5例で，狭窄や閉塞部位から皮質静脈や髄質静脈への逆流が認められた。Dural AVMでみられた還流静脈の狭窄や閉塞と，mixed pial-dural AVMやpial AVMでみられたものとは成因は異なると考えられた。脳AVMの血管撮影の読影に際しては，還流静脈系の狭窄や閉塞の有無，さらにそれらが存在する場合には皮質静脈や髄質静脈への逆流の有無，col—lateral routeとして還流している静脈への正常部血流の関与，についての詳細な検討が重要と考えられた。

We investigated angiographically occlusion or stenosis of draining veins in cases of arteriovenous malformations (AVMs). The subjects were 51 cases who were diagnosed as cerebral AVMs by angiography in our hospital between April 1973 and January 1991. Those consisted of 8 dural AVMs, 3 mixed pial-dural AVMs, and 40 pial AVMs. Angio-graphy was steroscopically done in all cases. Angio-grams obtained prior to treatment were retrospec-tively analyzed. Cases of dural AVMs or arterio-venous fistulae in the cavernous sinus were excluded from the subjects. Eight of 51 cases (16%) had occlusion or stenosis of draining veins ; i. e., 2 dural AVMs, 1 mixed pial-dural AVM, 5 pial AVMs. One of 2 dural AVMs was located in the sigmoid sinus, and another involved the superior sagittal sinus. One mixed pial-dural AVM was a vein of Galen aneurysm. Occlusion or stenosis was recognized at the junction of the vein of Galen to the straight sinus (3 cases), in the straight sinus (2 cases), at thejunction of the vein of Labbe to the transverse sinus (1 case), in the superior sagittal sinus (1 case), and in the sigmoid sinus (1 case). Two of 8 cases with occlusion or stenosis of draining vein presented with hemorrhage at the site of AVMs. In cases of pial AVMs, occlusion or stenosis of draining vein seemed be related to endothelial changes due to turbulent and irregular flow. On the other hand, in cases of dural AVM with dural sinus occlusion, sinus abnormalities may precede the formation of fistulous communications. In 5 of total 8 cases (63%), many engorged cortical and medullary veins due to a reflux from the site of occlusion or stenosis were seen. This suggested that those cases had a high risk of hemorrhage at sites far from AVMs as well as near the AVMs. Moreover, they seemed to have a high risk of dementia which was caused by diminished cerebral blood flow due to an increased venous pressure.