Unruptured intracranial aneurysms: natural history and clinical management. Update on the international study of unruptured intracranial aneurysms.

In guiding treatment decisions for all patients with unruptured intracranial aneurysms, it is important to compare size-, site-, and group-specific natural history data with size-, site- and age-specific treatment morbidity and mortality data. Because patient age has a major effect on operative morbidity and mortality, but relatively little effect on natural history, surgical treatment of an UIA patient over age 50 and any treatment of UIA patients over age 70 should be considered with particular vigilance. Optimally, patients should be evaluated and treated at high-volume centers in a setting that emphasizes neurovascular teamwork and unbiased presentation and delivery of different therapeutic option, including the option of observation, which is often appropriate for patients with UIAs.