Hi Mark, I’m not sure about prevalence but I had the caloric testing done and was shown to have 79% vestibular loss on my left side. The administrator of the test was flabbergasted and tried every which way to get a response. I was left with a diagnosis of vestibular neuritis and started vestibular rehabilitation.
When I kept getting worse and eventually found a Otolaryngologist, he read the caloric test results and said “I can see how that could have been misread but there is no doubt you have vestibular migraine” and tossed the test in the trash.
I’ve not had another test to find whether I have deficiencies or not. I have followed his treatment and have improved to near normal life.
If I could offer anyone suffering one bit of advice is to keep looking until you find a Otolaryngologist who you feel confident with the diagnosis and treatment plan.
Best wishes!