The definitions regarding concussion and how to recognise it are ever changing. We did a study on it in my final year at physio and I was involved in numerous studies providing normals. The reason for the studies were that alot of the tests we were using to identify concussion were easily positive when you were fatigued making them flasely positive for concussion. I'd like to say I'm up to date on the topic, but it still continues to change often and I'm not currently seeing anyone with concussion.
Do you have a local ice rink? Go ask them where their athletes go for physio. And ask that physio... Just a thought. Huge concussion rate in ice skating and ice hockey etc.