静脈還流障害を伴った局所脳虚血に関する実験的検討

The Focal Brain Ischemia with Disturbance of Venous Drainage

　静脈還流障害に伴った虚血性脳血管障害は出血性梗塞や脳浮腫を引き起こして生命予後，機能予後に大きく影響を与えることが知られている。この病態を解明する目的で，雑種成猫16匹で実験的に猫中大脳動脈閉塞モデルを用い，さらに静脈還流障害負荷を加えることにより生じる脳軟膜血管反応，局所脳血流量の変化，病理学的変化を検討した。静脈還流障害負荷群では，中大脳動脈閉塞のみのsham群と比較して脳軟膜血管径は有意に拡張し，血管反応性障害が強く，また局所脳血流量も有意に低下し，脳梗塞巣・脳浮腫の面積も静脈還流障害群では拡大した。これらのことより静脈還流障害群では相対的perfusion pressureの低下が強まり，本来penumbraであるべき部位にまで梗塞巣が拡大し，また脳循環に影響を与え，脳浮腫の発生に関与していると考えられる。このため生命予後，機能予後に大きな影響を与えるものと思われた。

The focal brain ischemia with disturbance of cerebral venous drainage often lead to brain edema and hemorrhagic infarction and make mortality and morbidity worse. So we tried to make sure of this fact using a middle cerebral artery (MCA) occlu-sion model in adult cat. The MCA was exposed by the transorbital approach and temporally obstruct-ed by Zen's clip. We divided the animals into two groups of eight cats. One group is only MCA occlusion group (sham group) and the other in MCA occlusion with disturbance of venous drainage (VRD group) . We ligated bilateral external jugular vein (EJV) and internal jugularvein (IJV) and injected embolic soarces from the left EJV to obstract the venous system of cat brain. The pressure of supe-rior saggital sinus was increased up to 18.7±5.3 mmHg by this method. A cranial window was made above the ectosylvian gyrus, which has poor anastomosis. The reactivity of pial arteriole and regional cerebral blood flow (rCBF) were observed through the window. And histological brain exami-nation was also performed. The result was that thereactivity of pial arterioles was severely disturbed in VRD group. The area of cerebral infarction and edema were also significantly expanded in VRD group. Considering from these facts., when the venous drainage was disturbed, cerebral perfusionpressure relatively decrease. Because of the decrease in cerebral perfusion pressre, cerebral infarction and edema probably expand to the area so called penembra.