Microsurgery for cerebral arteriovenous malformations: a dissection technique and its theoretical implications.

Surgical resection of cerebral arteriovenous malformations is often complicated by persistent bleeding from the nidus, which is difficult to manage. It has often been mentioned that the difficulty of hemostasis is caused by the fragile and pathological nature of vessels of the nidus. This may be one reason, but I hypothesize that the dissection procedure, which involves coagulation of the surface of the nidus, may cause obstruction of intranidal drainage and that this may cause increased intranidal pressure, especially at the late stage of resection. In operating on patients with cerebral arteriovenous malformations recently, I made an effort not to coagulate the surface of the nidus, and this technique has diminished hemorrhage problems effectively. I illustrate this technique herein with a resected specimen and plastic casts of the lesion.