Can you go back to the ped derm who first asked you about it? Perhaps that doc has the answer, but since you didn't know that hearing was an issue then..
It makes sense that decreased blood flow to any part of the body would affect it adversely.
As an aside, my son's eardrum also was not functioning properly and they said the same thing... too many ear infections. Yet, he hadn't had that many. Now, though, at almost 7, he hears just what he wants to (
Have you asked the CMTC expert these questions? http://birthmark.org/experts.php