Arterial aneurysms associated with arteriovenous malformations of the brain: classification, incidence, risk of hemorrhage, and treatment-a systematic review.

BACKGROUND: Aneurysms associated with brain arteriovenous malformations (bAVMs) influence the natural history of these lesions and pose important therapeutic challenges. However, the epidemiology, natural history, and appropriate management of the aneurysms associated with bAVMs are not completely understood due to the paucity of large and uniform studies. We performed a systematic review of published series examining the association between aneurysms and bAVMs with the purpose of clarifying the prevalence, risk of hemorrhage, and appropriate management of these lesions.

METHOD: PRISMA/MOOSE guidelines were followed. We conducted a comprehensive literature search of three databases (PubMed, Ovid MEDLINE, and Ovid EMBASE) on aneurysms associated with bAVMs. Only studies examining consecutive case series of aneurysms associated with bAVMs were included. From the collected studies, we extracted data regarding prevalence of bAVM-associated aneurysms, risk of aneurysm rupture in relation to bAVM location and aneurysm characteristics, and treatment-related outcomes.

RESULTS: Our systematic review included 44 articles with a total of 10,093 bAVMs. The proportion of bAVMs with an associated aneurysm was 20.2 % (95 % CI = 19.4-20.9 %). Among ruptured bAVMs with associated aneurysms, the aneurysm was the source of hemorrhage in 49.2 % (95 % CI = 43.7-54.7 %) of cases. Flow-related aneurysms were the most common source of aneurysm rupture (78.5 %, 95 % CI = 70.6-84.9 %). Infratentorial bAVM-associated aneurysms presented a higher risk of rupture (60 %, 95 % CI = 47.4-71.9 %) when compared with supratentorial lesions (29 %, 95 % CI = 21.4-38.5 %). Endovascular treatment of aneurysms associated with bAVMs had a cure rate of 80.0 % (95 % CI = 73.3-85.3 %), complication rate of 8.7 % (95 % CI = 5.5-13.1 %), and a good neurological outcome rate of 78.8 % (95 % CI = 72.5-83.9 %).

CONCLUSIONS: Twenty percent of bAVMs harbored arterial aneurysms. The presence of aneurysm increases the risk of bleeding of the bAVM, especially when flow-related or infratentorially located. Aneurysms associated with bAVMs should be treated promptly. Selective endovascular treatment of bAVM-associated aneurysms appears safe and effective.