BeachGirl,
I have not been able to find anything that tells me why dizziness occurs with ES. No one seems to know the reason. Even the doctor that diagnosed me was asking me how they were related. Vestibular rehab is a series of physical therapy exercises that re-train your brain to translate the cues from your inner ear (vestibular nerve) and your eyes and other senses such as your posture. It works very well when someone has experienced damage to the nerve. BUT the damage has to remain constant so your brain can understand the new condition. If the damage is constantly changing because of an ever growing styloid your brain can never fully compensate and you end up always dizzy.
My theories are: 1.) The styloid process (SP) (my SP was fused to my hyoid bone) puts pressure on the mastoid process which can inflame the inner ear nerve - vestibular nerve. It's the same explanation as to why TMJ can cause dizziness.
2.) ES can cause occipital neuralgia which can cause migraines which can manifest as vertigo. It is called Migraine associated vertigo (MAV).
3. Impingement of the carotid arteries reduces blood flow to the brain and vestibular nerve.
It is puzzling to doctors because the SP comes into contact with 4 cranial nerves. The vestibular nerve is not one of them.