I don't know about the ONS , but for the Vagus Nerve Stim. go to www. vnstherapy. com. It doesn't say anything about migraine treatment, but has a lot of info. on depression. My neuro. say it would probably do wonders for my headaches if i could find some way to afford it. I may press my insurance for geting it for depression and pray it helps my migraines too.
I hope you find something that helps you.