JJ a very informative post.
I'm pretty convinced about the link to classical migraine, as I've mentioned on this forum over the years. Strangely, two friends with lifelong migraine have been diagnosed with that leakage in resent years.
The release by the heart of a hormone was mentioned.
One thing I have not felt appropriate to mention was something I have read in the last few years. I can't remember where I read it, but I wouldn't have given any credence to a totally unqualified source, though it might have been a migraine-specific forum, and thus open to 'interpretation.'
"In the US, more people die of migraine-related stroke than from gunshot wounds."
It does of course include the elderly, but belies the belief that migraine is a totally benign malaise.
I have long believed each episode causes small amounts of damage - perhaps minute, but to me, this spells out the importance of ridding the patient of the triggers for migraine, rather than treating the symptoms.