Can you submit to journals after presenting cases as eposter in conferences? I had a few medical cases that I presented in conferences as an eposter, I sumbitted the case as eposter, It was presented as a slideshow in big screens in the conference
My understanding is that eposters are not considered publications; so can I submit these cases to journals? 

Some journals specify as a requirement that the case submitted should not be published before on other journals or electronically. Where do cases presented as eposter stand on this?
Very few medical journals consider a poster presentation a publication. So vanishingly few that I have never encountered one in my career. Indeed, the primary expectation of the posters I've encountered is "This'll someday be a paper, but these are the preliminary results."

As long as it hasn't been worked into a full paper as part of the conference, there's no reason to worry.

If you're concerned about it, you can include a sentence in your cover letter to the journal something like the following:

"This manuscript is not under consideration at any other journal, however the preliminary results have been presented as an ePoster at the Conference of Big Deal Science."