11 year old David Gill has had a hockey stick in his hand since he was only 5 years old. Being on the ice is his passion. But, three months ago, David got a concussion during a game and was knocked out. " I felt nauseous and I didn't really know what had happened, I was real dizzy, " says David.

While there are some physical symptoms such as headaches, nausea, dizziness and blurred vision, concussions usually don't cause bleeding or swelling in the brain and don't show up on x-rays. In an effort to diagnose his concussion, doctors used the ImPACT test, a computer program which measures attention span and memory.

" A concussion can be categorized as a transient loss of neurological function. You don't necessarily need to lose consciousness. Actually in most mild concussions in sports you don't lose consciousness, " reports brain injury specialist, Dr. John Knightly of Overlook Hospital.

"ImPACT" is a twenty minute computerized battery of tests that operates like a video game -- giving your brain a "physical," generating responses that are critical in helping to better identify the severity and recovery from the injury.

"With ImPACT you have a baseline test, so the student athlete takes the test and you have his data and then it is stored, to that rainy day when someone has a concussion. You take the test within 24 to 72 hours of the injury and you can see where he lies on his baseline and then depending upon where he lies on his baseline it helps guide us back to where he should be so he can be returned to play," explains Dr. Knightly.

But, if "ImPACT" was not done, data generated after the concussion can still assist doctors in diagnosis. "If they don't have their baseline they have normative values for a ten year old, twelve year old, eighteen year old so you can compare that to the baseline," says Dr. Knightly.

The key to a full recovery, says Dr. Knightly, is keeping the child out of the game for a long enough duration to heal. "The main thing is taking the child out of the competition. It is the biggest thing to prevent, to protect the brain from having a second impact, so we want to remove the child from that type of activity. If you break your ankle you have a walking cast, you break your brain, you don't see it, at least not in a mild traumatic brain injury. So your brain is not in a cast, it's not in a helmet. So what you want to do is protect your brain. They can last anywhere from a couple of minutes, to weeks to months. The more you give the brain rest, both academically and athletically the faster it will be, " says Dr. Knightly.

According to medical experts, typically 90% of concussions are resolved within three to four weeks. And, over a thousand schools and sports teams across the country are using "ImPACT."