You shouldn’t worry too much if your kid hits his or her head and the doctor says it’s just a minor injury, Canadian researchers said Monday.

While some grownups may experience delayed, and potentially fatal, bleeding in the brain after even minor accidents, this phenomenon is exceedingly rare in children, the researchers found.

“One of the things we worry about when we see children who’ve had a fall and hit their head is whether we’ve missed something serious,” said Dr. David Johnson of the University of Calgary in Canada, who worked on the new study, published in the journal Pediatrics.

That worry became very real to him, he said, when a girl he treated for a Head injury suddenly got very sick after having been fine for eight hours after a fall.

One of the blood vessels in her brain had ruptured, it turned out, and the building pressure in her skull left her with permanent brain damage before the doctors could intervene.

“Nobody had systematically looked at just how often this occurs,” said Johnson. “What we found was that it’s very, very uncommon.”

Over an eight-year period, Johnson and colleagues found almost 18,000 children who had been judged by emergency physicians throughout Calgary, Canada, to have only minor head injuries. Those injuries included cases in which the child did not have memory loss and hadn’t lost consciousness for longer than one minute.

None of the children went on to have bleeding in their brain leading to consciousness impairment more than six hours after they had first been evaluated. However, five had delayed bleeding in which their consciousness wasn’t impaired, corresponding to a rate of 3 in 10,000.

While the findings don’t mean that serious brain damage can’t occur in the first place, or that concussion shouldn’t be taken seriously, they should be reassuring to parents, said Johnson.

“A general recommendation to a parent is if their child after (the fall) is alert and interactive and has had no vomiting, then they needn’t worry,” he said.

Dr. Jeffrey Bazarian, who wasn’t involved in the study, said the findings meant that if a doctor determined that a child was fine, he/she probably was. But he stressed that parents should always see a doctor if they are concerned, since bleeding in the brain sometimes starts right away and might not always be easy to detect.

“The problem is this is hard for a parent to be able to judge, to be able to make this medical decision,” said Bazarian, of the University of Rochester in New York.

Especially in toddlers, he added, it can be hard to tell whether they have memory loss, for instance. “The younger kids are, the more cautious parents need to be about taking their kid to see the doctor,” he said.

SOURCE:  Pediatrics, online June 21, 2010.