Update on the Management of Unruptured Intracranial Aneurysms

Gregory J. Zipfel, M.D.; Ralph G. Dacey, M.D.


Neurosurg Focus. 2004;17(5) 

In This Article

Abstract and Overview

Over the past decade, several factors have led to a dramatic change in the manner in which patients with unruptured intracranial aneurysms are diagnosed and treated. These factors include the increased use of noninvasive imaging modalities for the diagnosis of intracranial aneurysms, publication of new natural history data detailing the hemorrhage risks associated with unruptured intracranial aneurysms, and the broad application of endovascular therapy for their treatment. With these new technologies and new natural history data has come considerable uncertainty about the optimal treatment strategy for patients with unruptured intracranial aneurysms. In this light, it seems prudent to review periodically and examine critically all recent data pertaining to the natural history and treatment of unruptured intracranial aneurysms, in an effort to provide a scientific update on which management recommendations can be based. This review article represents the authors' attempt at such an update, and it is their hope that members of the community of neurovascular surgeons might find this information helpful during their continuing efforts to provide optimal care for their patients with unruptured intracranial aneurysms.

A considerable debate regarding the optimal treatment of patients harboring unruptured intracranial aneurysms has developed in recent years, stemming largely from the influence of three main factors. First, increasing use of noninvasive neuroimaging modalities such as CT angiography and MR angiography in the outpatient setting has led to a marked increase in the number of truly asymptomatic, incidental unruptured intracranial aneurysms being diagnosed. Second, results from the first large-scale, randomized, multiinstitutional study directly comparing neurosurgical clip placement with endovascular coil occlusion in patients with intracranial aneurysms has been published.[42] In this study it has been suggested that endovascular therapy may have a superior safety profile compared with surgical intervention, at least for ruptured intracranial aneurysms that are equally amenable to both treatment modalities. Third and most important, the ISUIA,[27] which was designed to assess the annual risk of hemorrhage associated with unruptured intracranial aneurysms, has been published recently. Results from this study indicate that unruptured intracranial aneurysms may have a more benign natural history than previously determined.

In combination, these three factors have led to considerable uncertainty with regard to the optimal treatment for patients harboring unruptured intracranial aneurysms. Which particular lesions carry a hemorrhage risk significant enough to justify intervention, and when aneurysm treatment is warranted, which modality should be used? The purpose of this article is to review these issues critically and in detail, in an effort to provide a modern management strategy for unruptured intracranial aneurysms, and to provide the justification behind this paradigm.