Repeated Concussions Take a Toll on the BrainNovember 2, 2001 By Amy Norton
NEW YORK (Reuters Health) - Getting back into the game soon after sustaining a concussion could leave athletes vulnerable to further head injury, and potential problems down the road, new research suggests.
And investigators say their findings--from research on mice--apply not only to injured athletes but also to victims of accidents or abuse.
In experiments with mice, Philadelphia researchers found that animals showed greater neurological damage when they sustained a second mild brain injury within a day of the first injury.
This suggests that the brain may be particularly vulnerable to further injury shortly after an initial trauma, Dr. Tracy K. McIntosh and his colleagues report in the November issue of the Journal of Neurosurgery.
In their experiments, the investigators found that mice that sustained a single injury--given through a surgical procedure designed to simulate a mild concussion--showed problems with motor skills 3 days after the injury. Animals given a second injury 24 hours after the first showed more pronounced effects that were still present 7 days after the last injury.
Moreover, after a short period of recovery, the twice-injured animals showed a "profound" increase in movement problems about 8 weeks after their injuries, the researchers report.
Such delayed effects are a "frequent occurrence clinically," with patients complaining of dizziness, concentration problems and other neurological symptoms weeks after a head injury, McIntosh said in an interview.
McIntosh, who directs The Head Injury Center at the University of Pennsylvania, told Reuters Health that this study was set up to simulate a common scenario in sports such as football--a player taking part in practice the day after sustaining a mild concussion.
The findings, he said, suggest a player with such an injury should wait a day, at the very least, before getting back into the sport.
"We don't yet know the safe interval," McIntosh pointed out, noting that "more rigorous science" is needed to establish sound guidelines for athletes.
Experts suspect that among the long-range effects of multiple concussions is a greater vulnerability to neurodegenerative conditions including Alzheimer's disease.
And some research has shown that athletes in contact sports with a history of concussions perform worse on tests of mental function than similar athletes with no past head injuries--and the more concussions an athlete had sustained, the worse the test performance. Animal research has suggested that mild concussions early in life--like those a child could potentially get playing certain sports--may hinder learning capacity later on.
McIntosh emphasized that concussions should not be treated lightly by athletes and coaches, or anyone who sustains such an injury.
"A concussion is a traumatic brain injury," he said.
And the injury need not involve a loss of consciousness. Athletes who feel dizzy and disoriented after taking a hit to head, for example, should be taken out of the game.
"Parents should be watchful for signs (of concussion) later on in the evening," McIntosh noted.
Such signs include dizziness, headache and nausea, and if they are present, he said, the child should go to the hospital and his or her coach should be told about the problem.
SOURCE: Journal of Neurosurgery 2001;95:859-870.