I know this is an old post but I thought I would make a contribution.
Like Kitty, I have had compression of both internal jugular veins. A month ago I had the right styloid process removed but still having dizziness and pressure symptoms, so may need to do left side after another MRI.
We have had a brutal summer here in Sydney, and I have noticed that the pressure feels a lot worse (and dizziness too) in extreme heat. Our worst day was about two weeks ago when it got to 47 celsius (that’s 113 Fahrenheit for Americans)!
For me, symptoms seem to be a little better when it’s cooler.
I would presume that your blood pressure goes up with heat, and probably heart pumps faster to get blood to the skin to cool off… if you have compressed jugular veins, the blood can get into your head okay through the carotid arteries, but is impeded from going out due to the compression on the veins, so the pressure in your head rises, worsening symptoms. The weather obviously doesn’t get so hot in the summer in the UK, but when we did have a few very hot days, I did notice I felt worse too.
I have/had inter cranial heat=stroke like effects [haven’t had it since my surgery 1 month ago…but also haven’t gone hiking/mountain biking yet ] I found a bandanna for the neck with cooling beads in it at REI [sporting company…look online] that I used to decrease my symptoms. Now that I understand Eagles here is what I think happens… what Jules said above about blood going in but not out and/or the Baroreceptors in your ICA controlling blood flow to the brain can [according to my friend a nurse and research online] over or under send blood flow to the brain when they are irritated [like SP pressing the ICA]. The bandanna works by keep the “heat inflammation” down and helps keep vascular system flowing. It is like keeping a cool pack on your neck.
Hey I see how old this post was, and erased what I wrote. But post settings will not allow me to erase completely (embarrassed face). BTW thank you for posting I had something similar with dizziness and carotid artery impingement.