In the early years of AVM glue etimlizaboon, we worked to a hypothesis that maybe some complex AVMs could be completlely obliterated. Single pedicle small leasions were candidates, of course, also curable with excision. The few complex AVM cases that went on to complete obliteration days after a treatment had something in common – delayed outcome, and often low density or blood away from the nidus. It later made sense: to completely obliterate a mutli-pedicle complicated AVM, one needed to cause blockage of the main venous draiange, and the rest could clot. These were few and far between, without big bleeds ensuing.This brings up the glue versus ONYX. Is Onyx more likely to get the venous outlet and thereby produce complete obliteration? What about the risk of bleeding with venous outflow occlusions? Are there features of AVM venous drainage that we don’t know, but predispose to safe complete embolization? Rather than continuing the blind hope that a few of these cases will be completely obliterated, maybe there is place for vascular imaging study of the venous side of AVMs, seeking clues that predispose to this success. If the clues were known, maybe patients can be chosen for complete etimlizaboon as an intention rather than luck.