Stenosis of the internal jugular vein was not detected in any subject and blood volume flow (internal jugular and vertebral veins) in the supine position was comparable for the two groups. Indeed, the decrease in total jugular blood volume flow in moving from the supine to upright positions was less pronounced in MS patients versus controls (173 vs. 362 mL/min).
What is expected here? In normals the jugular flow would reduce going from supine to upright. Gravity causes the flow in the upright position to take a different path. So flow goes in the vertebral veins, and the IJVs collapse. If there is a drainage problem, they stay as patent as possible and do not collapse in the upright position. So we would expect the decreased flow in the jugulars of a CCSVI patient to be less pronounced when moving from supine to upright. This is exactly what was found. Have I got this right?