a very good friend of mine was in a similar biking accident he was in a coma for a week (doctors induced it afaik), he was utterly unrecognisable with tubes and all sorts coming out of him, I'm telling you this because it sounds very similar to your circumstances, my friend is now fully recovered albeit with some very nasty scars, the recovery process was hard though I would expect your brother to spout nonsense for a few weeks, my friend (Neil) would ahve hour long conversations with us about the most random things, whilst it was amusing it was also terribly sad at the same time. I dont know if the doctors have told you all this already, I just thought I would let you know that my friend made a full recovery so I hope your brother does too.
all the best chap it sounds as though some good luck is well overdue for you.