Brain arteriovenous malformations (bAVMs) are among the least common of causes of brain hemorrhage, seizures, or headaches. Embedded in the brain, their widely varying size, arterial feeders draining venous pattern and nidus complexity make them among the most challenging of disorders for attempted eradication. The low prevalence has created a literature long dominated by anecdote, only recently and slowly being clarified by epidemiological, pathophysiological, and imaging data. A first-ever randomized clinical trial seeks to determine if invasive intervention to eradicate the lesion--and its attendant risks of complications--offers a better prognosis than awaiting a hemorrhage before undertaking such efforts.