this is a tough one to plow thru---yikes!!
From what I'm reading, it looks like they developed a "dynamic" or movement related way to scan, by scanning while rotating the heads of healthy controls and pwMS/CCSVI. This created external pressure on the jugular veins by the sternocleomastoid muscle. In people with MS, this made a bigger difference on the opposite side of the turn---their veins had a larger cross sectional area. In healthy people, it didn't make as big a difference. This is because, in their opinion, healthy people have stronger, less pliant veins. The head turn doesn't compress their jugular vein as much, so the other vein doesn't need to enlarge.
People with MS/CCSVI showed an hourglass shape in the neutral position---without turning the head. They call this "miopragic" or simply dysfunctional, and say that it's due to "jugular collapse" They say it could be because the walls of the jugular veins in pwMS are different, possibly due to a collagen disorder. I think back on Dr. Dake telling us that Jeff's jugular veins were "sticky"--that he'd never seen anything like it. The balloon actually stuck to the walls of his vein.
They do not think it is because of muscle pressure, because it's at a higher level. They think it's actually the lining of the vein.
In normal people, rotating the head did not change the cross sectional area of the jugular vein on the opposite side, this happened only in pwMS.
The worse the CCSVI and MS, the more not normal the jugular veins functioned---they're really looking at this as a congenital venous malformation--and they are also saying that ballooning these kinds of veins would not be helpful. Which would certainly explain restenosis problems. sigh. And makes me wonder if stenting or open surgery really will be the way to go as we move forward.
we still do not know what we do not know,
Husband dx RRMS 3/07
dx dual jugular vein stenosis (CCSVI) 4/09