Thanks everyone. I really appreciate all of this information.
Cece, he did have a follow-up ultrasound in Albany. When he turned his head one way, the upper left jugular was completely open. When he held his head normally, it was compressed - I'm not sure by how much. So, as you say, I guess it's a physiological obstruction.
We have seen some slight improvement in my husband's face colour, energy, and I think balance in the first two days. His left hand kind of uncurled since immediately after the procedure and his left foot drag doesn't seem as pronounced. Today he seems more pale and tired though.