Peter,
Go For It!!
While not as severe as your injury, I have on 3 occaisions suffered head trauma. On each occasion I didn't know the day, month or even the year! I also had associated short term memory loss, which never returned. As a result I have had CT scans, and met with specialist etc, as I am sure you have. Fortunately I never had any bleeding, and apart from a couple of blank spots in my memory, I recovered fully. At the time I had the same worries that I wouldn't be able to pursue my goal.
I currently hold an unrestricted class 1 and get to sit in the right hand seat of an A320.
To get my medical and also get it converted to use in any new countries I am based in, I do have to submit reports from the doctors which treated me and jump through a few more hoops than my friends. I think its worth it.
As Old Smokey said, no two head injuries are the same. There is only one way to know for sure, so give it a go.
PM me if you would like to know more. And make sure you let us know how it goes.
Good Luck