Video: Former NFL players sue over brain injuries

>>> former nfl star junior seau who killed himself with a gun shot wound to the chest wends. today, his family members allowed to have his brain signed f studies for signed it could have been caused by repeat ed concussions. this after nfl players filed lawsuits against the league. it's an urgent issue on every field for every child and their parents during every contact sport . all our report tonight from nbc's keval tibbles.

>> harry carson played 13 years for the new york giants. his opponent today, post concussion syndrome .

>> once you're damaged from a neurological standpoint, you may never, ever be the same.

>> carson is one of a growing number of former nfls battling brain injurieinjuries. now more than 1500 of them are suing the league, the latest saying the nfl failed to take reasonable steps to protect players from devastating head injuries . away from the pros, efforts are under way to restrict rough contact between younger players.

>> we're going to limit the hours of the practice time where they can have any contact at all. and we're going to try to eliminate in practice any head to head contact.

>> and at the ncaa level, in addition to recommending baseline brain scans, new guidelines mandate if a concussion is suspected in any sport, athletes are pulled from the game until a qualified medical evaluation clear ezthem for play. some medical evidence suggested that three sun cushions could be the threshold where cognitive damage may occur. but that doesn't take into account the damage they may have had before turning pro.

>> they're working to understand the treatment of concussions and in a statement said any allegation that the nfl intentionally sought to mislead players has no merit.

>> this is very much like being in the military and going to war. except you're fighting different enemies or different opponents week in and week out.

>> for many former players, that balal continues long after they have hung up their cleats. kevin tibbles, nbc news, chicago.

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