Unruptured Brain Arteriovenous Malformations Should Be Treated Conservatively

The case for treatment of asymptomatic cerebral arteriovenous malformations (AVM) is based on the premise that the morbidity and mortality of treatment should be less than the expected morbidity and mortality associated with the untreated AVM for the remainder of the patient’s expected lifetime—in other words the natural history of a treated AVM must be better than that of an untreated AVM. The literature contains a wide range of data on this subject, and by taking examples from across this spectrum one can easily support any viewpoint. Therefore, for the purposes of this discussion, published data from the Columbia AVM Databank will be used because this data are relatively “modern,” are prospectively acquired and are frequently used to support a position of nonintervention for asymptomatic AVM.For many years, intracranial AVM were generally considered to carry a bleed risk of about 2% per year for asymptomatic AVM and around 4% per year for symptomatic lesions, with each hemorrhage having an associated neurological morbidity of 20% to 30% and mortality of 10% to 30%.1–6 Based on a combination of retrospective and prospective studies, sometimes without a clear distinction between symptomatic and asymptomatic AVM, and with some studies performed in the …