Children who suffered a head injury were twice as likely to sustain a second head injury within a year, say researchers, who advise parents to be cautious about the activities of their children, even if they seem to have recovered from an injury.
For the study, Bonnie Swaine of the University of Montreal and her colleagues looked at pediatricians' billings for treating injuries and conducted more than 10,000 telephone interviews with parents who had taken their injured children to hospital.
"Children who have a head injury are almost twice as likely to have a second head injury, a subsequent head injury …in the following six months and even inthe following year, as compared to children who injure their ankle or have a wrist sprain," said Swaine, a professor at the university's school of rehabilitation.
Swaine's previous research suggested that children show subtle problems with balance, co-ordination and reaction time for up to three months after a minor head injury, the team said in Monday's issue of the journal Pediatrics.
These problems may make it more difficult for children to perform complex tasks, which increases their risk of injury.
The effects of more than one head injury can be persistent, especially for the developing brain.
"There is a certain amount of healing but …the damage [to certain neural networks] is going to be long lasting," said Dr. Jamie Hutchison of the pediatric intensive care unit at Toronto's Hospital for Sick Children.
"With another injury on top of it, it just compounds or adds to the original injury."
The standard recommendation is for children to avoid sportsfor four weeks after a headinjury, butsome health care providers are now sayingchildrenshould besymptom-free before they return to physical activities.
That means no headaches, no nausea, no dizziness and no increase inirritability, Swaine said.
"Given that the majority of subsequent [head injuries] were found to occur five or sixmonths after the initial [head injury], a four-week restriction of activity may need to be re-examined," the study's authors concluded.
The study's authors hope the findings will help health care professionals to counsel childrenand their parents about reducing risk and promoting helmet use.
Younger children, boys and children with a previous head injury showed a higher risk of re-injury, but the results were inconclusive on whether particular sports or recreational activities are more hazardous.
In the meantime, pediatricians like Hutchinson advise parents to be careful about when they allow their children to resume playing sports, but not be overprotective, since the benefits of playing sports still far outweigh the risks of a head injury.