Looks to me like very significant compression of the IJVs between the styloids & the C1 processes, one of the smallest gaps between them I can recall seeing, & especially to have that both sides is unusual, so not surprising that he’s feeling rough!
I’m not tech savvy I’m afraid so can’t annotate the images for you to show you… as @Andy89316 says there are some other smaller blood vessels being pinched too, can’t comment on which ones they are, I’m not knowledgeable enough I’m afraid!
Certainly worth pursuing a surgeon who specialises in vascular ES though- hopefully the Canadian members can give you info, but off the top of my head I can’t think of any in Canada who could tackle this, as it seems likely your husband might need a C1 shave and maybe ballooning the IJVs. If you were able to afford treatment in the US, Dr Cognetti in PA seems more reasonably priced than some of the doctors, & I believe he’s now working with a Dr Heller to do C1 shaves , a few Canadian members have been to see him. Dr Hepworth in CO is a very good vascular ES surgeon too, and Dr Nakaji seems excellent too, in AZ, maybe easier for you to get to?
Here’s a link to the doctors list to save you hunting round for it…
Doctor Lists – no discussion - Symptoms and Treatments / Doctor Information - Living with Eagle
Good luck with your journey 