It may not be anymore, but madden definitely did have this before. I ended up smoking an opposing team's kicker or punter before the kick and their injury was listed as Major Concussion(Career Ending). That was the one and only time I've ever seen anything like that.
I don't know if they are removed from the latest edition but in '12 one of my receivers got popped hard and suffered a broken vertebrae. Turned out to be listed as career ending. I also saw a center labeled with the same. That was the first time in a long time I ever saw a CRI.
My guess is that they are still there but VERY rare.
XBL / PSN : IXIShogunateIXI | Do what you gotta do.