The role of sinus thrombosis in occipital dural arteriovenous malformations--development and spontaneous closure.

Two cases of dural arteriovenous malformations are presented. Both were associated with thrombosis of the sigmoid sinus. Without any treatment, recanalization of the sinus occurred in one case, while the dural arteriovenous malformation was persisting. In the second case, recanalization of the sinus coincided with the spontaneous closure of the malformation. The interrelationship of sinus thrombosis and dural arteriovenous malformations, and the possible mechanism of spontaneous closure are discussed.