These are the two studies that I referred to. The article you posted also refers to the Chinese study.
The study you found indicated that those women who were undergoing “medical management” all had AVMs that were Spetzler-Martin grades V or VI – i.e. would be expected to result in some deficits if they were operated on. So, the choice as to whether to operate or not was driven by that high score.
And as for the ARUBA study, I have previously read both the ARUBA study and it’s rebuttal. My conclusion of those two is that it remains perfectly unclear whether intervention or avoidance of intervention can be shown statistically to be significant. It is by no means these days a new study and capabilities have much improved in the intervening 12 years.
I don’t believe there is anything upon which we can place good reliance to tell us that intervention mode A, B, or C gives better outcomes or that abstention gives better outcomes.