Lisa, yes, yes, many people have AVM's and never know it ! They never experience any symptoms. I am one of those whose, one whose AVM was found by accident ! Well, no, I am not dead yet ! But I am 72 1/2 and so far, so good, thank God, I have not had ANY symptoms and hope I will die one day without ever having had one! Many AVM's are disovered during autopsy despite the deceased was never aware of having any symptoms of anything typical of an AVM.
Let's also remember there's not a great wealth of previous research and/or findings on AVM's because only technology in the last X number of years was developed so they could be found. Plus AVMs are rare. I think I've read only 300, 000 cases in the United States--such a small per centage of the population for medial science to be willing to pledge very many millions of dollars for research to hopefully benefit such a few.
Regarding technology advancements, the same is true for the coils and embolizations and gamma knife methods used these days unlike in yesteryears' absence of them. Which reminds us what a promising future of techonolgy and medical science discoveries there will be for future generations. How promising for today's young people with AVMs and those in future generations !