Let me remind you that the seven studies are meant to demonstrate whether there is an association between venous malformations and venous blood flow in the veins of the neck and MS, that is, whether there is an increased prevalence of that in patients with MS as compared to healthy controls. Basically, with some variations—some are in kids and some are in adults, and there are some variations in the protocols—all of these studies compare a group of MS patients with a group of healthy subjects. They look at the anatomy of the veins and at the blood flow to see whether there is a blockage of the blood flow. It's all done in a blind fashion, so they don't know whether the patient has MS or not. When the study is unblinded, they'll see whether there's a difference in the incidence of the malformations and blood flow in the two groups. That's the principle.
On December 7th, 2010. See this statement in context.