"We know that there are hundreds of thousands of pediatric emergency visits across North America for acute concussions," said Dr. Roger Zemek, lead author and director of the research unit at Children's Hospital of Eastern Ontario. "Approximately one-third of those children will continue to experience ongoing or worsening symptoms for one month following their original injury."
Zemek added that the actual rates are difficult to calculate, given that many children do not report injuries or do not get treated.
Concussion is a form of mild traumatic brain injury. If the effects last for weeks or even months, doctors refer to this as "postconcussive syndrome." Each child is different, so each may experience a unique set of symptoms, explained Zemek.
"Typically, children can have ongoing symptoms that are physical in nature. Examples of that would be ongoing headaches, dizziness, maybe even some nausea or vision changes," Zemek said. Other children may have symptoms that are more cognitive in nature, so they might have problems concentrating or feel like they're "in a fog. They can have symptoms that are more emotional or behavioral in nature, feeling sad or feeling low energy." Sometimes, patients can't sleep.
Although postconcussion symptoms usually go away within three months, some can last a year or more.
Typically, pediatricians recommend that patients get rest until their symptoms disappear. "Unfortunately, most of those recommendations were not based on evidence; they were based on expert opinion only," Zemek said.
Other experts agree that more work is needed in the area of concussions, generally.
"The big question following a concussion is: How long should kids and adults stay away from physical activity?" said Dr. Richard Temes, director of the Center for Neurocritical Care at North Shore University Hospital in Manhasset, New York. He did not participate in the research. "This paper is kind of the first step to addressing the timing of physical activity."
Noting that early physical rehabilitation is encouraged after a stroke -- severe brain trauma -- Zemek and his colleagues set to work to find out whether it might also help prevent lingering concussion symptoms.
Is exercise the greatest medicine?
To investigate the possible effects of physical activity, Zemek and his colleagues assessed more than 2,400 children and teens diagnosed with concussion. After rating each child's physical activity participation and postconcussive symptom severity using standardized questionnaires at day seven, the researchers assessed persistent postconcussive symptoms at day 28.
Of all the participants, about 70% became active again within seven days. Activity primarily consisted of light aerobic or sport-specific exercise, noncontact drills and even, in a small percentage of cases, full-contact practice.
Of the patients who began physical activity early, 31% were symptom-free and 48% had at least three persistent or worsening postconcussive symptoms at day seven. By comparison, 80% of those who rested for the first week after a concussion had at least three postconcussive symptoms at day seven. At 28 days, the proportion with postconcussive symptoms was nearly 40% among those who rested versus about 29% among those who resumed early activity -- a significant difference.
"I think there are many different ways in which exercise may be beneficial," Zemek said, explaining that activity can improve cerebral blood flow, promote neuroplasticity and release endorphins, which may heal the brain.
Getting out of the "home jail" can be a psychologically important factor for kids as well, he said, reinforcing the message that they are going to get better. However, he still urges caution: Patients should not go skiing, participate in collision sports or risk another head injury while symptomatic.
Temes wholeheartedly agrees. "This is not a stamp of approval to get back in the football game," he said, adding that the study tells families only that "some level of physical activity may be helpful in improving symptoms of concussion."
This was not a randomized control trial but a simple observational study based on self-reports from families, noted Dr. Lynn Babcock, associate professor in the division of emergency medicine at Cincinnati Children's Hospital Medical Center. Some attempt was made to guess at the quantity, intensity and timing of exercise after an injury, but objective data are still needed, she said.
"Still, we're pretty excited to see more evidence saying we need to better study this question," said Babcock, who was not involved in the research.
Zemek and his colleagues have begun a randomized clinical trial to learn more about preventing postconcussive syndrome. "One-third of all kids is too many," he said. "Exercise itself can be a great medicine."