What I would do, is continue to say that you want medical causes looked at FIRST before any behavioral analysis or intervention is done. And if you feel you have good medical explanations and there is still some behavioral issue, insist that medical information be taken into account.
By not letting them get at the medical records, you've put them in a bind. But, if they are only looking at the records to support their viewpoints, they won't see what you need them to see.
It reminds me of when schools used to force kids to be medicated for ADHD. (see link below). Maybe you can use some of that info in your case.
http://www.webmd.com/add-adhd/news/20051116/schools-cant-require-adhd-drugs
