Perianeurysmal edema is rare and is associated with expansion of intracranial aneurysms despite adequate endovascular treatment. The natural history of this condition is poorly understood. We present a case series of perianeurysmal edema to investigate the incidence, natural history and management of these aneurysms.

Retrospective analysis of endovascularly treated aneurysms from January 2001 to December 2012 was performed. Perianeurysmal edema either pre- or post-treatment as detected on MRI was used to identify cases.

Ten of the 838 patients demonstrated perianeurysmal edema. The median age was 51.5 (interquartile range 48 to 59). Of the 10 subjects, 50% (5/10) were male. Perianeurysmal edema was detected after the initial presentation and treatment in 70% (7/10) of the patients, with one patient developing headache after endovascular coiling, while the remaining 6 were found on routine follow-up imaging. Only 4 of the patients were ever symptomatic in the setting of perianeurysmal edema, with 3 of these patients improved clinically following treatment of the aneurysm. Radiological follow-up showed expanding neck remnants leading to a second endovascular coiling procedure in 50% (5/10) of the patients and a third procedure in 20% (2/10) of the patients to attenuate aneurysm growth.

Ten of the aneurysms treated with endovascular therapy in our case series demonstrated perianeurysmal edema. They are mostly asymptomatic, with no cases of re-bleeding identified, however perianeurysmal edema is associated with aneurysm re-expansion despite initial endovascular treatment.