In the United States, sporting activities account for an estimated 20 percent of the 1.5 million head injuries each year. One type of head injury, concussion, is relatively common in the NFL. Each year an estimated 100 to 120 concussions occur in the NFL (about one every 2 to 3 games), with quarterbacks at the highest risk. Recent studies suggest that concussion is even more common in younger athletes, with 1 in 20 high school football players sustaining a concussion each season.
Concussion, or mild traumatic brain injury, is defined by the Committee of the Congress of Neurological Surgeons as “a clinical syndrome characterized by immediate transient impairment of neural function such as alteration of consciousness, disturbance of vision, equilibrium, etc, due to mechanical forces.”
A player does not have to lose consciousness to sustain a concussion. Signs and symptoms commonly associated with post-concussion syndrome include any or all of the following:
Because an athlete may appear normal, a team physician or coach may not know if an athlete has sustained a concussion. Thus, it is critical that athletes understand the importance of reporting concussion symptoms.
One of the tools now available for clinicians to evaluate sports-related concussions is computerized neurocognitive testing, such as ImPACT, or Immediate Post-concussion Assessment and Cognitive Testing. Baseline neurocognitive testing has also been recommended, so the pre-concussion status of an individual athlete is documented. If a healthy athlete undergoes this type of test, then clinicians may compare to baseline results to interpret symptoms more accurately after an injury. Neurocognitive testing can also help guide return-to-play decisions.
Returning to play following concussion remains controversial. It is vital that players, trainers, and coaches evaluate the return on an individual basis, not based on a rigid timeline, in order to protect the brain from further injury, as well as to reduce the risk of multiple concussions and their cumulative effects.
Several different guidelines may be used, but they are not an absolute rule. Players should be 100 percent symptom-free both at rest and with exertion, and have a completely normal clinical neurological examination before returning to play. Even with these precautions, it can be difficult to determine if the brain has fully healed from the injury.
After all symptoms have resolved, healing still may be incomplete, and the brain may be at increased risk for Second Impact Syndrome, when a subsequent hit to the brain can cause serious brain swelling, hemorrhage, and even death. Second Impact Syndrome has not been reported in NFL players, but has been documented in high school athletes. Therefore, even more caution for return to play is required in a high school athletics setting.
Ultimately, preventing concussion is the goal. Over the past decade, manufacturers have improved helmet performance by installing thicker padding and providing fuller coverage over larger regions of the helmet shell. Studies have demonstrated that newer football helmets reduce concussion risk by 10 to 20 percent in collisions that are representative of the NFL player experience. However, not all concussions can be prevented with these helmet modifications.
Recently, researchers have analyzed video of NFL head impacts and reconstructed collisions in a laboratory. They found that the average impact speed in a concussion injury was approximately 21 miles per hour. Interestingly, no concussions occurred in players who struck others. This may be because the striking player uses his whole body in the impact, whereas the struck player’s head is the major part of the body involved in the impact. Further analysis of the striking player indicates that the key to the concussive blow is the head-down position, which results in the transfer of more momentum to the struck player.
Stricter enforcement of rules against head-down tackling techniques has lowered the risk of catastrophic cervical spine injuries and may lower the risk of concussion. Of note, football was one of the first sports to focus on prevention of head and neck injury, as indicated by the 1976 prohibition of "spear tackling," which involves initial contact with the head. This has lead to a decrease in the number of catastrophic head and neck injuries over the past few decades.