thanks for posting, cece. Sharon actually put that picture album up on our Alliance FB page, but I was in the room, and heard Dr. Zamboni's presentation on valves...and was really intrigued by his findings.
I was surprised to learn that 62% of normals were missing at least one valve, as shown on ultrasound...and that it might be an evolutionalry process.
And that the leaflets are only briefly closed on atrial contraction--but the veins are normally wide open.
These results were different than the Fox/Diaconu study which found valves in the majority of IJVs--10 healthy controls, 10 with MS=40 IJVs on autopsy.
Results: Thirty-seven of 40 IJVs contained valves: 29 bicuspid, 6 tricuspid, and 2 unicuspid.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3678575/
the Fox/Diaconu paper explains it this way:
Autopsy studies revealed the presence of IJV valves in 93–100% of subjects (Table 3).6,8,15 Similarly, we identified bilateral valves in 17 of the cadavers examined and unilateral IJV valves in the remaining three. Ultrasound studies generally reveal a greater percentage of subjects without IJV valves compared to autopsy studies, but this is most likely due to the increased difficulty of visualizing the valves with ultrasound.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3678575/
So--as many of the IRs have said--the closure and blockage of the vein by those pesky valves may well be a huge part of the problem for people with CCSVI. And the fact that normals' valves seem to "disappear" on ultrasound scans may be further proof of this fact.
cheer