I don't normally draw attention to this sort of thing but I was surfing and found this article an NFL/NHL concussions to be supremely well written.

To add- I have heard they are developing a blood test that looks for proteins that signify brain trauma (concussions). The FDA is insanely slow with this sort of thing but should things pan out we will have a simple yes/no blood test within a year or two. I look forward to getting rid of this subjective bullshit.