This case report demonstrates delayed rupture of a cavernous carotid fistula and aneurysm into the temporal lobe 12 years after treating a direct cavernous carotid artery fistula using detachable silicon balloons. The ultimate treatment was performed using arterial endovascular sacrifice. Successful treatment of cavernous carotid fistulas may ultimately lead to formation of cavernous aneurysms. Although these lesions rarely cause intraparenchymal hemorrhage, the risk for such an event must be taken into consideration when patients are treated for the initial lesion.