Unruptured intracranial aneurysms: An updated review of current concepts for risk factors, detection and management

Abstract

The management of patients with unruptured intracranial aneurysms (UIAs) is a complex clinical challenge and constitutes an immense field of research. While a preponderant proportion of these aneurysms never rupture, the consequences of such an event are severe and represent an important healthcare problem. To date, however, the natural history of UIAs is not completely understood and there is no accurate means to discriminate the UIAs that will rupture from those that will not. Yet, a good understanding of the recent evidence and future perspectives is needed when advising a patient with IA to tailor any information to the given patient's level of risk and psychoaffective status. Thus, this review addresses the current concepts of epidemiology, risk factors, detection and management of UIAs.

Introduction

An intracranial aneurysm is an acquired focal outpouching (typically either saccular or fusiform) of a cerebral artery wall [1]. Its most feared complication is rupture, causing blood to erupt into the subarachnoid space with potentially fatal and frequently disabling outcomes [2], [3]. The consequences of an aneurysmal subarachnoid hemorrhage (aSAH) are devastating, with at least a quarter of such patients not surviving the rupture or its immediate complications, while leaving roughly half the survivors with permanent disabling neurological deficits [4].

With the greater availability of technical improvements and the ever-widening indications for noninvasive vascular neuroimaging [5], unruptured intracranial aneurysms (UIAs) are increasingly being discovered incidentally and an steadily growing number of patients are being referred to or seeking counseling from specialized centers regarding opportunities for screening (for example, for fear of occult UIAs after a relative has suffered an aSAH) [6]. However, UIAs represent a challenging situation to manage for several reasons:

• while the vast majority of UIAs never rupture [7], [8], [9], the consequences of such an event are severe and represent a major healthcare problem [4], [10];

• the natural history of UIAs is still not entirely understood and there is no accurate way to discriminate UIAs likely to rupture from those that will not [11], [12];

• the currently available treatments for repairing UIAs are invasive and associated with non-trivial morbidity, a risk particularly relevant in previously asymptomatic patients [13];

• the popular belief that an UIA is an imminent and ever-present peril has important psychosocial effects in patients with identified but untreated UIAs [14], [15].

Therefore, screening might, in some cases, not achieve its ultimate goal of improving quality years of life.

As a consequence, when offering screening for UIAs or advising for interventional vs. conservative management in patients with UIAs, physicians face a complex situation where no option is risk-free.

The optimal management and counseling should therefore focus on tailoring each encounter to the patient's specific level of risk and psychoaffective status, based on the available (albeit incomplete) evidence.

The American Heart Association (AHA)/American Stroke Association (ASA) issued guidelines for the management of UIAs in 2015 [16]. The present review does not intend to provide further guidelines, but aims to address the latest evidence on the epidemiology, natural history, risk factors, clinical and imaging presentations, treatment and follow-up of UIAs.