A concussion is a common type of traumatic brain injury, frequently suffered in contact sports, such as football. As more serious long-term effects of concussions have been revealed through medical studies, some professional sports leagues have revisited how they treat players who have suffered concussions.
Approximately 300,000 of the 1.5 million head injuries reported each year in the United States are sports-related, and approximately 9% of these require hospitalization
Reasonable estimates show that between four and 20 percent of college and high school football players will sustain a brain injury over the course of one season. The risk of concussion in football is three to six times higher in players who have had a previous concussion.
A concussion has most recently been defined as a “complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces”, which is most often transient with symptoms frequently including amnesia, confusion, headache, dizziness and fatigue; there are typically no “hard” signs of neurological abnormality (e.g., motor or sensory loss).
"When you think about what the problem is, it is not head trauma," Hoge said. "It is how head trauma is cared for. That is the issue. You are going to have concussions in every sport known to man."
Over the past decade, strategies for the medical management of concussion have undergone significant transformation as scientific knowledge has accumulated to suggest that mismanagement of the injury can lead to serious consequences, particularly in younger athletes.
The perception of sports concussions has undergone a gradual overhaul throughout the past decade where an injury that was once considered to be inconsequential has come to be understood within the neuropsychological and medical communities to be an injury with quantifiable changes to the brain that are both transient and persistent.
Unfortunately, there have been few studies evaluating the effectiveness of different helmet designs in reducing concussions. The studies that have taken place have tended to be non-randomized, retrospective analyses, and have thus suffered from the same general pitfalls including selection bias and overreliance on subject recollection.
Most symptoms associated with concussion are transient; however, there are several ways in which concussions can have lasting symptoms. For example, in some cases of concussion, memory impairment has been shown to last for months. Furthermore, post-concussion syndrome (PCS) may occur, especially in situations where an athlete is not properly treated following a concussion. PCS presents with physical, cognitive, emotional, and behavioral symptoms that can take months or even years to resolve.
The literature to date regarding cumulative effects is not definitive. Some researchers have reported that groups of athletes with a history of multiple concussions perform more poorly on neuropsychological testing compared to those with fewer or no concussions, whereas others have not. Some researchers have reported that athletes with a history of multiple concussions report more subjective symptoms during preseason testing, whereas others have not.
The lack of convergent evidence across studies and the meta-analysis suggests that lingering neurocognitive difficulties (a) are difficult to detect with standard neuropsychological testing and/or (b) might be present in only a subset of athletes and are thus obscured in group analyses.