Slurred, incoherent speech? Double vision? He's Keith Friggin' Richards! That's SOP.
I love Keith. Great guitarist, fine song writer and — even by rock standards — an idiosyncratic singing voice. His solo albums are the only things related to the Stones that have been worth listening to for years. (I highly recommend "… with the Expensive Winos Live at The Hollywood Bowl." Amazing.) This is the man whom I have always assumed could mainline Drano and live. My working theory has always been that only two things were going to survive nuclear war — cockroaches and Keith. You think a bump on the head is going to slow him down? Keith will outlive us all. And laugh doing it.