TORONTO -Twice as many Canadian children are suffering strokes than was previously believed, but too little is known about treatment to prevent the lifetime of damage they can cause, one of Canada's leading pediatric stroke specialists says.

Dr. Gabrielle deVeber, head of the Children's Stroke Program at Toronto's Hospital for Sick Children, said brain-damaging strokes in kids are "much more common than was previously recognized."

A national registry of young stroke victims directed by deVeber since 1992 has found a doubling of new cases in the last 10 years. Strokes were once believed to strike two to three of every 100,000 Canadian children; neurologists now put that figure at five to six per 100,000.

But studies to determine the best way to treat childhood strokes and prevent recurrences are desperately needed, deVeber said in an interview Wednesday from Vancouver, where she was addressing the World Stroke Congress.

While there have been hundreds of carefully controlled studies to find the best treatments for adults, "there has not been a single randomized controlled study in pediatric stroke," deVeber said, adding that doctors figure out therapies for kids by "extrapolating from adult treatments." Those include clot-reducing drugs such as Aspirin and TPA.

But she said "children are very different than adults" - their blood vessels, blood-clotting mechanisms and brains are not the same - and treatment needs to be tailored specifically for youngsters.

Dr. Philip Teal, a spokesman for the Heart and Stroke Foundation of Canada, said about 50 children, ranging in age from newborns to teenagers, will suffer strokes this year across the country. Unlike adults, whose strokes are usually related to high cholesterol, diabetes, smoking or high blood pressure, childhood strokes may be linked to congenital heart disease, various diseases of the arteries or problems with blood clotting.

There are two main types of strokes: hemorrhagic, which involves bleeding into the brain, and ischemic, which is caused by a blockage in blood vessels.

"It's still a relatively rare disease (in children)," but stroke can leave kids disabled and devastate their families, Teal said from Vancouver.

"Over half of the children who have suffered a stroke have persisting, truly lifelong limitations as a result of the stroke," said Teal, a neurologist at Vancouver General Hospital who specializes in adult stroke but consults on the condition in children. "Because it starts at an early age, it's truly a life-changing event for them.

"Often they are walking with some limitations, they may have a stiff or weak leg, they may not be able to participate in sports, they may need" a cane, crutches or braces, he said. "There is certainly an impact on their quality of life if they're not able to fully engage in normal childhood activities, participate in sports, ride a bike, run with their friends, climb, that sort of thing."

Fortunately, he said, children's brains are more "plastic" than adults' brains, so they are capable of developing new neural pathways that may limit impairment to speech and other brain functions.

Still, some stroke victims experience learning and behavioural difficulties that continue throughout life, he said.

"One of the tragic things about pediatric stroke is it completely devastates parents, certainly initially. They can't comprehend how their child could have a stroke. They almost invariably didn't know that children had strokes. They have an ongoing anxiety about a recurring stroke, and it has been a major blow for them."

Also, strokes don't just disable, they can kill: five per cent of Canadian newborns and 12 per cent of older children who have strokes die each year.

DeVeber said doctors - even in high-tech children's hospitals - often don't recognize the signs of stroke in a child (including sudden weakness or tingling on one side and sudden speech loss), so the standard 12-hour window of opportunity to administer clot-busting drugs to minimize damage passes without a proper diagnosis.

"Often the parents and the family are more aware than the physicians are that it's a stroke," she said, explaining that parents have told her they thought their child had had a stroke because he became weak on one side, but the doctor told them, 'Oh no, kids don't have strokes, or 'He's better, don't worry.' "

DeVeber is heading a new international registry involving researchers from Canada, the United States, the United Kingdom, Australia and China to conduct studies aimed at finding the best treatments for children with strokes.