Aneurysmal wall enhancement and perianeurysmal edema after endovascular treatment of unruptured cerebral aneurysms.

Introduction: Perianeurysmal edema and aneurysm wall enhancement are previously described phenomenon after coil embolization attributed to inflammatory reaction. We aimed to demonstrate the prevalence and natural course of these phenomena in unruptured aneurysms after endovascular treatment and to identify factors that contributed to their development.

Methods: We performed a retrospective analysis of consecutively treated unruptured aneurysms between January 2000 and December 2011. The presence and evolution of wall enhancement and perianeurysmal edema on MRI after endovascular treatment were analyzed. Variable factors were compared among aneurysms with and without edema.

Results: One hundred thirty-two unruptured aneurysms in 124 patients underwent endovascular treatment. Eighty-five (64.4 %) aneurysms had wall enhancement, and 9 (6.8 %) aneurysms had perianeurysmal brain edema. Wall enhancement tends to persist for years with two patterns identified. Larger aneurysms and brain-embedded aneurysms were significantly associated with wall enhancement. In all edema cases, the aneurysms were embedded within the brain and had wall enhancement. Progressive thickening of wall enhancement was significantly associated with edema. Edema can be symptomatic when in eloquent brain and stabilizes or resolves over the years.

Conclusions: Our study demonstrates the prevalence and some appreciation of the natural history of aneurysmal wall enhancement and perianeurysmal brain edema following endovascular treatment of unruptured aneurysms. Aneurysmal wall enhancement is a common phenomenon while perianeurysmal edema is rare. These phenomena are likely related to the presence of inflammatory reaction near the aneurysmal wall. Both phenomena are usually asymptomatic and self-limited, and prophylactic treatment is not recommended.