Concussions happen in all sports but particularly football and soccer, and are difficult to diagnose, treat and manage.  A concussion is a bruise to the brain and can result in various levels of brain injury just as a bruise to the muscle can.  There are many grades of the injury from the minor being where an athlete is temporarily dazed to a severe concussion where the athlete has a loss of consciousness on the field of play for greater than 30 seconds.  It can sometimes be difficult to tell when an athlete has had a mild concussion as he may be able to play several plays after the injury (as Steve young related after one of his concussions many years ago).  Sometimes the only way it can be determined that the athlete had a mild concussion is that he comes off the field confused about what just happened.  It is further difficult to manage these injuries because it is difficult to tell the severity of bruising of the brain that has occurred from the simple sideline tests that can be performed.  There is significant debate among Sports Medicine Specialists and Neurologists about how long an athlete should be held out from contact before adequate recovery has occurred, because the tools to determine how significant the injury to the brain is are limited.  Even MRIs are somewhat limited in their ability to predict long term brain dysfunction from a concussion.  Recently there have been some tests for brain function that have been developed, one of which is called IMPACT, that test a variety of psycho-motor skills through an online test that can be done on the computer.  These recent evaluation tools have allowed Sports Medicine Specialists to better asses the degree of injury and recovery from that injury.  In the past and even currently some of the symptoms that are consistent with a concussion that has not yet resolved are headache, light-headedness, nausea, confusion, memory loss, and headache with physical exertion.  Most Sports Medicine Specialists would agree that all of these symptoms need to be resolved for at least a week before potential for contact.  Others have even a more conservative view that would hold athletes out for a longer period of time especially if it is a second or third concussion in a season.  The athletes mentioned above are in various stages of recovery from their concussions.  Scott Johnson of BYU has returned to play, Tim Tebow is expected to return to play next week if his symptoms have resolved, and Rahim Moore had a grade 1, or mild, concussion this past Saturday and will probably be out of contact at least until next weeks game.  The most important thing to remember is if concussions are not treated with adequate rest from re-injury, there can be permanent brain damage that can be subtle such as difficulty concentrating, headaches, and difficulty in school that can be lifetime effects.