"Keith Primeau has not put on his full hockey equipment since the day he retired from professional hockey, a career cut short by several concussions, not all of them documented.

To say he has good days would be stretching the definition.

"I can honestly say here that there isn't a day that goes by that I don't sense I've damaged my brain," said Primeau, who retired in 2005 at 34. "Whether I stand up and get a headache or I'm resting and I get a headache, I know exactly why I had to stop playing."

The former Philadelphia Flyers star has made it his post-career crusade to teach people about concussions. Primeau suffered at least four in his career, and if his own lingering symptoms weren't enough motivation, three of his four children have suffered documented concussions through their sporting activities.

Teaching moments, unfortunately, have been many in the NHL in 2011."