Peri-Aneurysmal Brain Edema in Native and Treated Aneurysms: The Role of Thrombosis

Cerebral peri-aneurysmal edema (PE) is typically associated with giant partially-thrombosed aneurysms and less frequently with smaller aneurysms treated with endovascular embolization. An understanding of the pathophysiologic mechanism of PE is still limited. We report 3 cases of cerebral aneurysms associated with PE. We describe 2 cases of giant partially thrombosed aneurysms surrounded by vasogenic edema with apposition of an intramural and juxtamural thrombus. Our third case is a smaller aneurysm inciting vasogenic edema several years after coil embolization. Vessel-wall magnetic resonance imaging (MRI) showed avid wall enhancement and an enhancing thrombus embedded within the coils, reflecting inflammation of the aneurysm wall and proliferation of the vasa vasorum. Thrombosis within the aneurysmal sac and walls, both in native and treated aneurysms, may promote inflammatory changes and sustain the occurrence of PE. Vessel-wall MRI has a potential role in the evaluation process of this subgroup of aneurysms.