We analyzed a series of 30 patients undergoing complete surgical resection of large arteriovenous malformations (AVM's) of the brain between 1986 and 1995 for intraoperative and postoperative complications. In 17 patients preoperative embolization for AVM was performed and the extent of embolization was about 20% to 80%.
First, in patients without preoperative embolization procedure, postoperative edema around the resected AVM on CT scan was analyzed. Remarkable or moderatice edema was seen more frequently in patients whose AVM consisted of the long feeding arteries and short draining veins. Normal perfusion pressure after AVM resection might cause the breakthrough of autoregulation (NPPB) and provoke edema of the brain.
In the patients undergoing preoperative embolization for AVMs, the extent of postoperatvie cerebral edema on CT scan was consistently smaller than in the patients without an embolization procedure. In two patients whose AVMs had long feeding arteries and short draining veins, intracerebral hemorrhage and remarkable cerebral edema were provoked postoperatively. The cause of these hemorrhages and edemas was considered to be secondary to venosinus thrombosis that occured after the AVM resection from postoperative serial angiographical and CT scan studies.
Based on these experiences, we concluded that NPPB after the AVM resection may enhance the cerebral postoperative edema, but remarkable postoperative edema or intracerebral hemorrhage are secondary to the venousinus thrombosis provoked by the venous blood flow reduction after AVM resection.
