This is just a personal experience, so take it with a grain of salt.
I participated in a study looking at Internal Jugular Vein flow through ultrasound and various mouth and tongue positions. A Dentist collaborating with Dr. Hauser noticed that many of their patients with reduced IJV flow had similar dental and airflow issues, and could see increased IJV flow with certain tongue and jaw positions.
I don’t think the study is published yet, but the Dentist strongly recommended I look at myo dentistry, which is currently rare. Myofunctional orthodontics is a way to restructure the mouth and jaw in a way that also re-aligns the teeth, improves air flow (tracheal and nasal), and supposedly makes people look better. It’s similar to braces, which just align the teeth, only it applies force beyond the gum line. It also involves some physical exercises and a slightly modified diet.
Although this works better for children, it’s worked with older adults if a bit slower. I’m over 40, and am seeing an improvement just 6 months into a 2 year plan. It’s easier for me to hold my tongue in a position which increases my IJV flow, and it feels like my neck is less tight since my lower jaw is starting to come forward.
Issues going in: narrow mouth, jugular vein issues, crooked lower teeth, could not breath through nose about 90% of time, deviated septum, snoring.
Already better: wider upper jaw, better breathing, less snoring, slightly less IJV symptoms, can breath through nose about 80% of the time.
It is pricey (requiring monthly dental visits), but has worked for me better than chiropractic has, and helps with nose breathing which comes with its own benefits (like getting sick less often).
I don’t think this will ever work as an alternative to a styloidectomy, but every bit helps.
Downsides: it’s slow, expensive, mildly uncomfortable, and you’ll talk like you have potatoes in your mouth because essentially, with the orthotics in place, you do.