ljelome wrote:However, preventing vein wall smooth muscle contraction allows passive dilation
of veins and when a critical diameter is reached, a functioning venous valve becomes dysfunctional
or incompetent. As half of a women’s adult lifetime is under the influence of progesterone,
and this is exacerbated markedly during pregnancy, it is no wonder that primary venous insufficiency
is twice as common in women than in men.7
Interesting! The difference is that in the legs, a dysfunctional valve means one that is stuck open and weakened and can't close, and so it can't move blood upwards or keep blood from falling downwards, and you end up with pooled blood and varicose veins. That kind of dysfunction can happen in the jugular veins too, and there is some research on it, but until CCSVI there was no research on what is basically the opposite type of abnormality, where the valves are stuck closed.
I am trying to think what effect passive dilation might have on stuck closed valves or on total capacity of the jugulars and other collateral veins. I would think if it does have an effect, it would be a good effect, by increasing capacity in the jugular and collaterals? It would even have an effect on the venules of the brain, but not the capillaries, since those do not have smooth muscle?
Anonymoose, I'm open to the possibility of some CCSVI malformations being congenital and some acquired over time. The valves themselves might be stuck congenitally but not thickened, and then thicken over time. There was the Beirut research that found much more CCSVI in people with RR MS of "advanced duration" which meant over ten years since diagnosis. There is also a new IVUS with 10x the goodness of regular IVUS, and looking at people with CIS using the superIVUS might answer this question. But I don't think any CCSVI researcher has a superIVUS yet! We know that some CCSVI malformations are congenital because they are formed in ways that can't be formed except when initially formed. (I am explaining this oh-so-not-clearly.) Also the emissary veins are fascinating if it can be shown that they are enlarged in people with MS, and if it is true that since the emissary veins are only formed prenatally because they actually run through channels of the skull and so can't be developed later in life, then that is also support for the congenital argument.