总的来说每年出血风险为2%-4%。出血后前5年出血风险增加,出血后第一年再次出血风险最高,据报道>30%。[13]Mast H, Mohr JP, Osipov A, et al. 'Steal' is an unestablished mechanism for the clinical presentation of cerebral arteriovenous malformations. Stroke. 1995;26:1215-1220.http://stroke.ahajournals.org/cgi/content/full/26/7/1215http://www.ncbi.nlm.nih.gov/pubmed/7604417?tool=bestpractice.com[16]Hernesniemi JA, Dashti R, Juvela S, et al. Natural history of brain arteriovenous malformations: a long-term follow-up study of risk of hemorrhage in 238 patients. Neurosurgery. 2008;63:823-829.http://www.ncbi.nlm.nih.gov/pubmed/19005371?tool=bestpractice.com[17]Mast H, Young WL, Koennecke HC, et al. Risk of spontaneous haemorrhage after diagnosis of cerebral arteriovenous malformation. Lancet. 1997;350:1065-1068.http://www.ncbi.nlm.nih.gov/pubmed/10213548?tool=bestpractice.com然而,对于无出血病史的患者,其出血风险似乎被高估,年出血风险可能低于1%。在这些患者中, 治疗的风险可能高于破裂出血的风险。[18]Stapf C, Mast H, Sciacca RR, et al. Predictors of hemorrhage in patients with untreated brain arteriovenous malformation. Neurology. 2006;66:1350-1355.http://www.ncbi.nlm.nih.gov/pubmed/16682666?tool=bestpractice.com[19]Wedderburn CJ, van Beijnum J, Bhattacharya JJ, et al. Outcome after interventional or conservative management of unruptured brain arteriovenous malformation: a prospective, population-based cohort study. Lancet Neurol. 2008;7:223-230.http://www.ncbi.nlm.nih.gov/pubmed/18243054?tool=bestpractice.com