Unruptured Cerebral Arteriovenous Malformations

Abstract

See related article, pages 1243–1247 As noninvasive brain imaging for sometimes dubious indications becomes more and more ubiquitous, greater numbers of asymptomatic lesions are being found and management decisions are being required. Cerebral arteriovenous malformations (AVM) represent a particularly challenging subset of these lesions, given their overall low incidence and the high frequency with which some form of multimodality treatment may be required for complete obliteration. In order to make an educated decision regarding therapy, a thorough understanding of the natural history is needed, but not always available. In the case of intracranial AVM, a combination of retrospective and prospective studies have yielded a generally accepted bleed risk of 2% to 4% per year with an associated neurological morbidity of 20% to 30% and mortality of 10% to 30% with each bleed.1–12 Unfortunately, all of these reports constitute level V evidence and suffer from the usual methodological problems of case series, including selection bias, treatment bias and inconsistent follow-up. In this issue of Stroke , Choi et al13 update these outcome statistics using data prospectively entered into the Columbia AVM Databank from 1989 to 2004. The authors examine the clinical outcome after first and recurrent hemorrhage in patients with untreated cerebral AVM. Rankin Score (RS) and National Institutes of Health Stroke Score (NIHSS), both acutely and after follow-up, were collected. Outcome results were also stratified according to the anatomical location of the initial hemorrhage (nonparenchymatous or parenchymatous). In addition, outcome after parenchymatous hemorrhage was compared with outcome data from survivors of non–AVM-related intracerebral hemorrhage from the Northern Manhattan Study (NOMAS). The study was not designed to provide data regarding the de novo risk of AVM hemorrhage or the risks of treatment. After their initial hemorrhage, the majority of patients (72%) had an RS of ≥2 and 61% …