Michael Christmas remembers the circumstances of the crushing hit, but the remainder of the game is just a blur.

Then a junior and playing running back at North Hall in 2002, Christmas took a handoff from the quarterback and charged through the line of scrimmage like he had done so many times before. However, a fast-charging linebacker for Gainesville High hit the line at the same time, resulting in a helmet-to-helmet collision.

After that ferocious hit, Christmas managed to return to the game later in the second half, but remembers none of it. Nor does he remember attending school earlier in the day.

“I know after the game, I went to the training table and the doctor took a look at me, and they made the decision to take me to the hospital,” said Christmas, now 24.

After arriving at Northeast Georgia Medical Center, doctors also found that Christmas had suffered a small amount of bleeding on the brain, which required an overnight stay. Once the bleeding had absorbed by the next morning, he was discharged.

Medically, what Christmas had suffered was a concussion.

Concussions are common in football, and vary greatly in severity.

Sometimes, they don’t even require contact to occur, according to Dr. Bennett Omalu, a forensic pathologist and founding member of the Brain Injury Research Institute at West Virginia University.

“The brain floats freely in your skull,” Omalu said. “If you’re moving very quickly and suddenly stop, the brain bounces.”

Due to the varying nature of concussions, there is no single remedy to bring a football player back to the field safely. On top of that, concussions do not show up on an MRI or CT (Cat) scan.

Symptoms of concussions also vary depending on the nature of the accident. They can lead to a headache, nausea, difficulty balancing, fatigue, drowsiness, trouble sleeping, vomiting, dizziness and blurred vision, and more, said University of Georgia director of sports medicine Ron Courson.

“The symptoms of concussions vary widely,” Courson said. “A concussion is a neurological injury, and you have to evaluate each one individually.”

According to data presented by the Journal of the American Medical Association, the chances  of of subsequent head injuries goes up significantly after a player suffers the first concussion.

Christmas, the son of Trojans football coach Bob Christmas, falls into that category. Though he was concussion-free the remainder of his junior season, he endured two mild concussions as a senior. His second concussion took place returning a kickoff against Chestatee. The third took place against Johnson. Both caused only minor, temporary pain.

After enduring three concussions and a trip to a specialist in Atlanta on the same day as the Trojans’ Senior Night game, he was told by doctors that it would be better if he didn’t play football anymore. After bring his jersey to the doctor’s office — not knowing what the verdict from the experts would be — he returned to North Hall and was allowed to play, mainly due to the convincing of his mother, Peggy.

“I ended up getting to play Senior Night and then the next week in our playoff game,” Christmas said.

Estimates on the number of concussions that occur annually depend on the source. According to the Journal of the American Medical Association, the rate is near 300,000 annually. However, the Brain Injury Association of America says that number is closer to 3.8 million.

Doctors agree that it is important to properly diagnose concussions with football players, as well as warn athletes of long-term implications that come from repeated head injuries.

Dr. Jeffrey Kutcher, a leading neurologist who studies concussions, appeared before Congress to report his findings that concussions from football can lead to significant problems down the road, even though a minority of cases result in life-changing side effects.

Kutcher, a member of the University of Michigan department of neurology and a team physician, said there is plenty still to be uncovered about the magnitude of concussions on football players, but fully supports states getting involved to enact guidelines for players of all ages who have experienced a concussion.

“We just don’t have the science in place yet about concussions to know all the answers, so it’s important to err on the side of caution,” Kutcher said. “You don’t have to have perfect science to have safe policy.”

Concussions are something trained healthcare providers take seriously, whether it be high school, college or the NFL. The one element they share is the desire to make the best decision with a player’s safety in mind.

At the high school level, most coaches defer injury-related programs to an athletic trainer or team doctor who works with the team. No longer do coaches shrug off a hard hit as a player getting his “bell rung” or “clock cleaned.”

Northeast Georgia Medical Center athletic trainer Chris Phillips, a team trainer with Chestatee High, assesses 12 cranial nerves with players through observational testing, such as gauging a player’s balance, sight, memory, cognitive abilities and reaction times.

Phillips says that deciding whether to withhold a player from practice after a hit is aa judgement call. If a player suffers a concussion, Phillips says he consults with team doctor Dr. Michael Gottsman before coming to a joint decision about if or when a player will return to the field.

“Any time you are dealing with a concussion, you have to take it very seriously,” Phillips said. “As a trainer, I have to build a good rapport with the kids, so they feel comfortable coming to me if something is wrong.”

It’s Phillips’ belief that concussions are possibly on the rise because players today are bigger, faster and stronger than ever. He chalks it up to physics and the inevitable result  bodies in motion collide.

However, it is difficult to get a consensus in this regard since most healthcare personnel believe that concussions are under reported.

To combat this, the NCAA educates players about what a concussion is and how to identify the symptoms.

At Georgia, players are given baseline testing to have a reference point to compare their cognitive functioning should a head injury occur.

Courson says it is too simplistic to label any headache a player experiences as a concussion. He’s a member of the sports medical community that doesn’t believe concussions are on the rise, however that doesn’t mean they are to be taken lightly.

“If a player has a concussion, we pull them away immediately,” Courson said. “They may even have to be held out of class if the symptoms are severe enough.”

Advances in sports nutrition have also been used to help with football players. Courson says that players are given DHA (same as an Omega-3 fatty acid), which helps repair interrupted brain function.

The NCAA has cracked down spearing and tackling with the crown of the helmet.

The NCAA’s rules committee has also endorsed a rule to ensure players be cleared by medical personnel before returning to the field.

Dr. Kutcher noted that Washington state has the most aggressive legislation addressing when a player under 18 can return to the field. Last year, it adapted a measure that would require players who show concussion symptoms to be cleared by a licensed medical care provider. California, Missouri, Massachusetts, Connecticut, Rhode Island and Pennsylvania have similar measures under consideration.

“You can’t have a cookbook approach to concussions since they are all so different,” Dr. Kutcher said. “It all starts with good legislation, educating football players, people writing about the issue, trainers and medical personnel in place, and a return-to-play plan.”

The stakes are high, and the consequences can be dire, doctors say.

Neuropathologist Dr. Ann McKee studied tissue samples taken from the brains of deceased NFL players who experienced multiple head injuries, some in their 30s and 40s at the time of their death. She found the tangles of fibers in the brain more closely resembled that of an 80-year-old suffering from Alzheimer’s disease.

“Repeated blows to the head can lead to dementia, loss of cognitive function, memory problems, mood disorders, psychosis, paranoia, criminal behavior, drug abuse and suicide,” said Dr. Omalu, who has researched the postmortem brain tissue of 27 former football players and found evidence of CTE (chronice traumatic encephalopathy), a degenerative disease of the brain cause by repeated head trauma in many.

Among those is former NFL wide receiver Chris Henry, who died in late 2009 after falling from  the back of a truck driven by his fiancee.

In Henry’s case, Dr. Omalu says concussions and head injury fit the pattern of CTE. The player had a background of criminal history, impulsive behavior and even a threat of suicide before ultimately falling from the truck to his death.

“Chris Henry had a turbulent behavior profile,” Dr. Omalu said. “People need to be aware that damage from concussions or repeated blows to the head can cause serious brain damage.”