Also, is getting hit in the back of the head the same thing as walking into a pole or metal beam? Because I don't see why they would be any different, and if anything I would think a smack to the back of the head is worse than walking into a metal pole, because there is far more force and speed put into the hand making collision with the back of your head. I think that it could be highly likely to get a concussion from a slap, because your brain probably shakes around uncontrollably in your head after you get smacked.