How exactly? Sleep is deaths cousin, when u get put to sleep so hard you need smelling salt to wake your brain you know you got a severe concussion, which is not too far from being comatose? Only difference is your brain responded to the ammonia so you awoke.
Because pac didn't spend a night in the hospital, The blood to the head is still pumping it only turns off (ko) to prevent damage to anything, The ct scan showed pac had no concussions. death in boxing usually happens when a guy takes multiple hits and then goes out or even worse they don't go out but keep getting beat to a pulp that's when the brain takes so much damage that it possibly can never recover...Pretty much his brain suffered just enough injury to say fu*k this i need to save this guy and shut down his body and not keeping him awake to keep taking blows ripping the brain tissue or going out with his brain bleeding. However they it will effect him as a older man in his 60's+ is a totally different story but with all the test they did he didn't have a concussion or brain injury from that..
Think about rampage he's been put to sleep once in his career but tko'd badly by wand and shogun twice he took more punishment to the brain from not being ko'd then the 10 knees it took for his brain to say ok i gotta save this guy and shut off. He didn't have a concussion from it but obviously his brain took punishment the two times he didn't go out and more so the time it took so much for him to go out. He can still take a hell of a punch today..
Now compare that to chuck lidell once rampage put him out he did have a concussion and had a 4 month no contact suspension but he could no longer take a punch when he got back he was knocked out by shots he use to walk through.
We'll see in pac mans next f!ght if he can still take a decent shot but if he gets ko'd he will need to retire because at that point his brain will shut off alot faster because it fears damage..