There are two I can think of where I knocked myself out cold, and probably have some long term CTE.
First was a back 5-0 on a small park hubba, I put both wheels on the deck and zooted out right to the bottom. Hit my head pretty hard and woke up with ten people above me. I was foggy for a day or two after.
Second, Was about two months later. I hung up on a pivot fakie in a six foot concrete bowl, right to my head on the flat. Was out for five or so minutes and got a sweet ride to the hospital in an ambulance. I had post concussion symptoms for about a month after. I still haven’t been able to get myself to commit to a pivot fakie since. I can do blunt fakie and feeble fakie, but the pivot fucks with me.