hmm. I don't know. I know I get weird sensations in my head, like something is crawling around above my left ear sometimes. It is painless, but definitely hinky. I have never felt the air bubble thing though.
I don't know about doing a followup MRI, etc, that would def be something to ask your neuro about. I remember Mark saying in a post once that MRI's expose you to a lot of radiation or something not good, so be aware of that too.

(hope I remembered right).
Good luck...