When a head injury occurs, the response to it depends a little bit on the severity at the moment. If an athlete takes a blow to the head and they're laying on the ground and they're not moving, and you're not sure if they're conscious, whether or not they have a concussion actually is the least of his concerns, says William P. Meehan, III, MD, Director of the Sports Concussion Clinic at Boston Children's Hospital. "Are they breathing? Are they awake? Is their mouth open so that they can breathe, or is there something impeding it like their mouthguard or their tongue? I worry did they fracture their cervical spine at the time? I start with all the emergent things first.

"Once those things have been addressed where we know for sure that that's not a problem, then you move into the area of OK this is a concussion. Now concussion is the most common neurological injury in sports, but it's not the only one. And so even if it's less dramatic, even if the athlete's just a little off balance or seems a little confused and they come to the sideline, I start by doing what's called a neurological examination. Basically trying to rule out other injuries, and make sure what we're dealing with is a concussion."

