Woooah this sounds serious.  Any type of neck or back injury can mess you up for the rest of your life.  Apparently Jason was doing some acrobatic tumble thing (he is a bad ass dancer ya know) and wound up fracturing his neck.  See what he tweeted and twitpic-ed from the hospital bed below.

I fractured my neck doing tumbling & acrobatics 4 tour! Always tryin 2 push boundaries 4 YOU! Like my new chain? fb.me/131rt0qU2—
Jason Derulo (@jasonderulo) January 04, 2012