Persistent primitive trigeminal artery-cavernous sinus fistulas: report of two cases. Two cases of persistent primitive trigeminal artery-cavernous sinus fistulas are presented. In one case, the fistula was treated by using a two-balloon tandem technique. This method was accomplished by introducing, inflating, and detaching a silicone balloon into the trigeminal artery, thus preserving the carotid and basilar blood flow. An unusual case of a similar fistula with only contralateral exophthalmos is also reported. The relationship between this type of fistula and the presence of aneurysms on the persistent primitive trigeminal artery and the relationship with traumatic events are discussed. 