This is an excellent question. I personally think professors should know about any learning disabilities you have. You're not giving them a fair chance to help you if you don't tell them. (If you were in SPED growing up, you'll have no trouble getting services. Just be glad you weren't in school when I was. Colleges weren't required to do anything, and many didn't. )

The hydro, IMO, is a different issue. If you have had serious problems with it (severe headaches, balance issues, seizures, etc), they should know, and you need to be prepared to tell them what it is and how it affects you. If not, I don't think I'd bother.

LIZARD