Unruptured Intracranial Aneurysms

Intracranial aneurysms (IAs) are acquired lesions, with a genetic predisposition in selected patients. They are very common in the population, occurring in ~2% of people in the United States. Intracranial aneurysms may present with subarachnoid hemorrhage, the most feared complication of IA, but most commonly they are detected on brain imaging performed for reasons unrelated to the IA. Once detected, the key question is whether the unruptured intracranial aneurysm needs to be treated, or can safely be left alone. This decision is complex and is dependent on numerous factors, including the natural history of the unruptured intracranial aneurysm, in comparison to the risk of unruptured intracranial aneurysm treatment. For those not treated with interventional treatment, repeat imaging at some intermittency may be recommended. In this article, the data regarding the natural history of unruptured intracranial aneurysm and the procedure-associated morbidity and mortality are reviewed, as well as the predictors of hemorrhage, and the likelihood of unruptured intracranial aneurysm growth should conservative management with intermittent repeat imaging be recommended.