A concussion is an injury to the brain that comes from a solid hit to the noggin (such as getting tackled in football) or a shockwave (such as an explosion). Symptoms range from obvious brain injury to very subtle changes in behavior. Researchers aren't completely sure how a concussion works, but it definitely affects the brain's ability to function correctly, at least short term.
Diagnosing a concussion can be complicated. There are several signs or symptoms (what's the difference?) that can indicate when someone has suffered an injury to the brain. It pays to have someone specifically trained in recognizing concussions to evaluate possible symptoms. These are some red flags to look for after a hard hit on the head:
- loss of consciousness (getting knocked out)
- inability to pay attention
- memory loss (for example, an athlete should know where the game is, what quarter/half it is, who scored last, who the team played last week and which team won the last game he or she played)
- losing balance or coordination
It's not required to have all of these -- or even more than one -- for an injury to the brain to have occurred. Indeed, there's a common misconception that in order for an injury to be considered a concussion the victim has to get knocked out or not remember what happened, but that is incorrect.
It's one thing to be a little dizzy after hitting your head accidentally and resting until you feel better, but it's something else entirely to go back into a football game and risk another hit.
Don't underestimate the power of a concussion. It may seem like a minor injury, especially if the victim wasn't knocked out. You may think you just "got your bell rung" when a hit on the noggin makes you see stars. However, once a person has suffered one concussion, it's easier to get the next one.
Guskiewicz, K.M., et al. "Research based recommendations on management of sport related concussion: summary of the National Athletic Trainers' Association position statement." Br J Sports Med. 2006 Jan; 40(1): 6–10.
Theye, Fred and Karla A. Mueller. "'Heads Up': Concussions in High School Sports." Clin Med Res. 2004 Aug; 2(3): 165–171.