Mike Gee:
I personally don't think there is any truth to the statement that the dura mater should contract where there is craving, but I am not an MD, of course.
i don't know about the dura mater specifically either, but i appreciate bhante vimalaramsi because i appreciate anyone who says 'there must be more' (and is able to substantiate it with a first-hand account of accomplishment).
also, i can report that there is something to the point about head tension. a tension inside my head 'popped' when i got stream-entry (which i did by practising the very same mahasi method vimalaramsi criticises by the way), then later, funny sensations (approximating a pleasant tension) at the crown of my head showed up and stayed for quite a while, and other unusual sensations played on the back of my head for a long time (which had the effect of making my sense of perspective seem wide and expansive).
like chuck wrote, you may be able to verify the coincidence in which certain tension felt in the head occur along with stress rather quickly. whether these tensions have anything to do with contractions of the dura mater is perhaps another matter.
tarin