DE-NOVO ANEURYSM FORMATION - REPORT OF 2 CASES

We report 2 cases of 'de novo' aneurysm formation in a vessel which ap peared to be normal at a previous angiography. The first patient devel oped an anterior communicating artery aneurysm nine years after occlus ion of the right internal carotid artery by Gianturco coils for the tr eatment of a giant intracavernous carotid aneurysm. In the second case a 'de novo' aneurysm of the internal angle A1-A2 segment of the left anterior cerebral artery developed 6 years after successful clipping o f another aneurysm of the same location. De novo formation of an aneur ysm in a vessel which was found to be normal in a previous angiographi c study, may occur as result of hemodynamic changes, such as after int ernal carotid occlusion or in presence of an arteriovenous malformatio n or variations of the circle of Willis. However, definite hemodynamic changes may also be absent. We conclude that patients operated on for aneurysm clipping must be periodically explored by magnetic resonance angiography to evaluate the possibility of de novo appearance of anot her aneurysm.