We answer some frequently asked questions about concussions.
What is a concussion?
A concussion is a brain injury that results in temporary loss of normal brain function. It's usually caused by a blow to the head but could result from an impact to the body that causes whiplash of the neck and skull. Concussions are most often identified by their common symptoms: headache, dizziness and confusion, loss of balance and temporary memory loss.
Scientists don't know what a concussion looks like inside the brain, whose intricacies scientists are only beginning to explore. Such injuries don't show up on X-rays or standard MRIs. A concussion is more a functional disturbance than structural injury, on a cellular level disrupting the brain's ability to transmit electrical signals.
Most of the brain is made up of white matter that provides the pathways by which different areas of the brain communicate with each other. The gelatin-like mass floats within the skull. The spinal fluid surrounding the brain acts as a buffer that keeps it from bouncing around when a body moves.
When there's a big blow to the head, the shock-absorbing fluid can't keep the brain from bouncing off the inside of the skull, possibly twisting or contorting. Research suggests this causes "shearing'': stretching of the neurons that make up those delicate white-matter pathways. While full function almost always returns, it's up in the air whether those pathways repair themselves over time or whether the brain develops alternative pathways.
"The brain is very complex,'' said Dennis Molfese, who directs the brain lab at the University of Nebraska-Lincoln. "No one has a clue how it works.''
How serious is a concussion?
Three major medical panels — the American Academy of Neurology, the American Society of Sports Medicine and the Zurich International Conference on Concussion in Sport — have in the past year released major consensus statements on concussion care.
Their general conclusion: Though concussions are serious, the best knowledge today suggests that in nearly all cases they lead to just temporary impairment of brain function.
With proper rest, between 80 percent and 90 percent of concussion victims are symptom-free and regain full cognitive function in seven to 10 days. For only a miserable minority do symptoms persist beyond a month as they suffer what clinicians call "post-concussion syndrome.''
"The current consensus guideline, and what most clinicians in the field believe right now, is a single concussion by itself is not a serious problem as long as the person is allowed to heal,'' said Lori Terryberry-Spohr, brain injury program manager at Madonna Rehabilitation Hospital in Lincoln. "Kids who are young and healthy recover pretty well from these things.''
Repeat concussions, however, are more serious. Research suggests that someone who has suffered a concussion is two to six times more likely to suffer another. People suffering multiple concussions are also far more likely to suffer prolonged brain dysfunction.
Also, in rare cases, if a person under 21 suffers a second concussion — even a minor one — before the first one has healed, it can cause the brain to swell. The result of these "second impact'' injuries is most often death, or profoundly disabling brain damage. That makes it even more critical that young athletes don't return to play too soon.
Those consensus statements on concussion came despite research in recent years that has challenged the notion that concussions carry few long-term consequences. The statements didn't ignore or reject such research, but concluded that too much remains unknown.
Research at Boston University has linked repeated concussions to chronic traumatic encephalopathy, a serious degenerative disease commonly shorted to CTE.
Also, numerous studies in recent years have found that concussions may produce small but perceptible changes in brain function that persist. Two ongoing studies at UNL appear to show that football players with a history of concussion show subtle differences in visual acuity, processing speed and brain electrical activity compared with non-concussed players.
Some new studies suggest it doesn't even take a concussion, just an accumulation of the routine lesser hits football players absorb play after play, to produce such subtle differences in brain function. A Purdue University study last year found that a season of football hits led to small but clear electrical changes in the brains of non-concussed high school players.
"We don't really know the long-term implications of that, but it can't be good,'' said Thomas Talavage, one of the Purdue researchers. "We obviously need to study this more.''
How common are concussions?
They're certainly not limited to football. Experts call concussions a near-universal human condition. Whether it's from falling off a bike, being injured in a car crash or knocking heads on the playground, it's an injury that a large percentage of the population will experience at some point in life.
"We all bounce our heads off something as toddlers or kids,'' Molfese said. "And most of us turn out reasonably well."
Americans suffer millions of concussions each year, with estimates of annual sports and recreational concussions ranging widely, from 300,000 to 3.8 million.
Most concussions don't result in trips to the hospital, although hospital visits due to concussions have been on the rise nationally and in Nebraska, likely because of heightened concern over the injuries. Figures for 2011 suggest on average that nine Nebraskans every day visit a hospital because of a concussion, including one a day related to sports.
Are concussions a problem in other sports?
Concussions occur frequently in all contact sports, and even in some sports in which hitting isn't part of the game.
Studies suggest the concussion rates for high school hockey players aren't far below those in high school football. The rates in women's soccer are also elevated. One national study found that the rate for women's college soccer players was slightly higher than that of college football players. Heading the ball in soccer is coming under increased scrutiny.
When men and women play the same sports, studies consistently find women have higher concussion rates. It's not clear whether that's because men have stronger necks, reducing the likelihood of whiplash, or whether women are more honest in reporting symptoms.
Most studies have consistently shown that no organized sport produces concussions at higher rates than football. Football also ranks among the largest of participation sports for youths, with 3 million young players, more than 1 million in high school and some 75,000 in college. That will continue to keep football in the spotlight as more is learned about concussions and their consequences.