As a player with a head injury you can be your own worst enemy.

Even if you are impaired, you aren't communicating what the medical staff need to make an accurate diagnosis on the field.

I had my bell rung on more than a few occasions playing rugby and even when I was sidelined for blood, I still twisted the staffs arm to get me back on the field.

The big thing from experience is also Karius emotional state, sure he was now impaired, but the crying which we all took as you just cost your team the cup, can be a symptom of concussion.

You can also get flash knockouts on the field, where you have no idea that you actually blacked out.

After the incident usually 72 hrs you are basically a zombie, lots of nausea and mushroom floaty feet. You can also lose all your colour around your face like death warmed up.