Recently it has been shown that two brain proteins (GFAP and UCH-L1) are released into the blood after brain injury.
This looks like a promising new approach.
There is a general account of this here
https://www.sciencedaily.com/release...0328114638.htm and the Abstract of the paper is here
http://archneur.jamanetwork.com/arti...icleid=2506517.