@arctic loon - I won't use any medical terms and descriptions - only simple words. When PT with
thumping being 24/7 and disappears only when chewing, it's usually the carotid artery and that can also associate to jaw processes, although in very rare cases it could be something else. The process to carotid/jaw can not be seen well on a MRI. MRA, MRV and CTA also have drawbacks for this. If you have heart problems then these tests are needed. A color ultrasound would indicate a carotid problem and this test is not loud. Wear noise blocking headphones anyways.
Being older, if you smoke or eat a lot of junk food would indicate carotid with heart associations more so than a vein/artery problem from an injury such as being the vertebral artery from whiplash. Hypertension And PT has no limitations.
Besides this - what vitamins that you take and foods eaten can associate to increasing PT, eye problems with floater and hypertension. I found out that NAC can cause or increase eye problems and headaches with having hyperactive PT of a carotid nature. Vitamin A - 3 cups of sliced watermelon or 1 cup of other melons daily for a few months can as well. I found several internet hidden very serious professional medical PT articles on this. If you also have other facial, neck, head or eyes discomfort then also get complete blood work that includes a complete vitamin panel and D-dimer.
Need to determine if you have heart problems. If so a beta blocker may help such as Levobunolol, Nebivolol and Sotalol. These are the safest ones with tinnitus.
When there's thumping - maybe also with a pattern motor generator sound, then the carotid artery has more blockage than normal. An ultrasound is the best test to note how much blockage.
So many articles on discussion above and other possible PT concerns, where a few mentions of words are very helpful, but most content may not apply to a particular person. Many professional articles also state different thoughts and it takes a lot of research time to get to real concerns, real answers and proper treatments.