here's a case by Dr. Sclafani in which he performed vertebral vein angioplasty:chronic-cerebrospinal-venous-insufficiency-ccsvi-f40/topic10680-6540.html#p188661
If a jugular is hypoplastic or occluded, I would think the vertebral veins rise in importance. But this was an unusual case. In almost all patients, to the best of my knowledge, the IRs are not interrogating or treating these veins. These veins are smaller than the major veins being treated (jugulars, azygous, renal, even the innominate). I think these veins do warrant investigation but perhaps not immediate investigation since there is so much to be done. I am curious what there is in the medical literature to support the presence of valves in the vertebral veins.
I don't think the vertebral veins would be limited to causing symptoms only when we are upright. If there is CCSVI in the major veins, the verts may be used as collaterals, even when supine; and if they have a blockage too, then we are ever more affected.http://www.ajnr.org/content/23/8/1418.full
Ultrasonographic Evaluation of Vertebral Venous Valves
of interest because the stenosis in the IJVs is often valvular and so stenosis in VVs may be valvular as well