Diplopia:-mri brain isch chngs & infarcts. now thirsty esp at night & constant salty taste in mouth. could mini stroke be cause or what else?

Yes: Any type of brain disorder or brain damage can cause diplopia if the parts of the brain that deal with eye movements and with vision are affected. Causes include strokes; aneurysms; increased pressure inside the brain from trauma, bleeding, or infection; brain tumors; migraine headaches; etc...

Yes, no, maybe so: "mri brain isch chngs & infarcts" isn't specific enough. The isch chngs & infarcts can't be just anywhere. Diplopia from strokes tends to improve at least partly; is yours? As for thirsty esp at night & constant salty taste in mouth: Strokes don't cause that. My guess is it's a med side effect, maybe the bisoprolol. Avoid "ministroke"; the term is so poorly defined it's essentially meaningless.