Management of intracranial aneurysms associated with arteriovenous malformations

Abstract

<jats:p>Intracranial or brain arteriovenous malformations (BAVMs) are some of the most interesting and challenging lesions treated by the cerebrovascular neurosurgeon. It is generally believed that the combination of BAVMs and intracranial aneurysms (IAs) is associated with higher hemorrhage rates at presentation and higher rehemorrhage rates and thus with a more aggressive course and natural history. There is wide variation in the literature on the prevalence of BAVM-associated aneurysms (range 2.7%–58%), with 10%–20% being most often cited in the largest case series. The risk of intracranial hemorrhage in patients with unruptured BAVMs and coexisting IAs has been reported to be 7% annually, compared with 2%–4% annually for those with BAVM alone. Several different classification systems have been applied in an attempt to better understand the natural history of this combination of lesions and implications for treatment. Independent of the classification used, it is clear that a few subtypes of aneurysms have a direct hemodynamic correlation with the BAVM itself. This is exemplified by the fact that the presence of a distal flow-related or an intranidal aneurysm appears to be associated with an increased hemorrhage risk, when compared with an aneurysm located on a vessel with no direct supply to the BAVM nidus. Debate still exists regarding the etiology of the association between those two vascular lesions, the subsequent implications for patients’ risk of hemorrhagic stroke, and finally the determination of which patients warrant treatment and when. The ultimate goals of the treatment of a BAVM associated with an IA are to prevent hemorrhage, avoid stepwise neurological deterioration, and eliminate the mortality risk associated with recurrent hemorrhagic events. The treatment is only justifiable if the risks associated with an intervention are lower than or equivalent to the long-term risks of disability or mortality caused by the lesion itself. When faced with this difficult decision, a few questions need to be answered by the treating neu-rosurgeon: What is the mode of presentation? What is the symptomatic lesion? Which one of the lesions bled? What is the relationship between the BAVM and IA? Is it possible to safely treat both BAVM and IA? The objective of this review is to discuss the demographics, natural history, classification, and strategies for management of BAVMs associated with IAs.</jats:p>

Complications associated with the use of flow-diverting devices for cerebral aneurysms: a systematic review and meta-analysis

“…This probably reflects the balance between complete aneurysm thrombus formation and thrombosismediated inflammatory disruption of the aneurysmal wall. 30 Xiang et al 78 also suggest that stagnant aneurysmal flow and excessively low wall shear stress may promote wall degradation via the inflammatory pathway.…”

Aneurysms Associated with Brain Arteriovenous Malformations

“…Proximal flow-related aneurysms should be treated with either surgical or endovascular modalities, depending on their location, morphology, and operator experience. 6,13,28 Treatment of the associated AVM may be postponed for a later time and can be either surgical, endovascular, radiosurgical, or even conservative (Fig 4). In cases in which the bleeding source is an associated aneurysm and AVM treatment is not indicated, endovascular or surgical closure of the aneurysm alone should be pursued.…”

“…12 The reported incidence of IAs associated with AVMs varies considerably among different studies (2.7%-58%). 13 In a recent meta-analysis on the natural history of brain AVMs, the incidence , an AVM nidus in relation to a branch of the left middle cerebral artery is noted. At the left internal carotid artery bifurcation, a hemodynamically relevant aneurysm is located proximal to the feeding pedicle of the AVM nidus (proximal flowrelated aneurysm) (black arrow).…”

Novel use of flow diversion for the treatment of aneurysms associated with arteriovenous malformations

“…4,[6][7][8]10,11,13,15,16,20,23 They are typically located within the AVM nidus or on proximal feeding vessels. AVMs with associated aneurysms have an increased rupture rate of 7%-10% when compared with the 2%-4% rupture rate of AVMs without related aneurysms.…”

“…AVMs with associated aneurysms have an increased rupture rate of 7%-10% when compared with the 2%-4% rupture rate of AVMs without related aneurysms. 4,7,8,20 Although definitive treatment of the AVM should be the ultimate goal and has been shown to lead to the regression of aneurysms on proximal feeding vessels, 11,20 this may not be feasible in some instances because of patient demographics or AVM size, venous drainage pattern, or anatomical location. In these circumstances, focused treatment of the associated aneurysm alone may be reasonable to help reduce the risk of intracranial hemorrhage back to the baseline level of AVMs without associated intracranial aneurysms.…”