August 8, 2001
SickKids study leads to better understanding of stroke in children
A team of Canadian researchers led by scientists at The Hospital for Sick Children (SickKids) has completed the first large-scale, multi-centre study to determine the incidence and characteristics of sinovenous thrombosis, a type of stroke that occurs in children due to blood clots blocking the brain's venous flow. The research is published in the August 9 issue of The New England Journal of Medicine.
With the use of a national registry, the study evaluated 160 children with sinovenous thrombosis and established that this condition in children is a serious disorder which results in neurological impairment or death in half the cases. Newborns, who were found to be most commonly affected, make up 40 per cent of children who experience this type of stroke.
Principal investigator, Dr. Gabrielle deVeber, a paediatric neurologist and a clinician-scientist in the SickKids Research Institute, describes sinovenous thrombosis as difficult to diagnose because symptoms are subtle. Symptoms in children experiencing sinovenous thrombosis include headaches and seizures and only rarely weakness down one side of the body as commonly seen in other strokes. CT scans can miss the diagnosis, and MRI is needed in most cases.
"Large population-based studies are necessary to study childhood stroke including sinovenous thrombosis in children," said Dr. Gabrielle deVeber, who is also an assistant professor of Paediatrics at the University of Toronto and holder of a Stroke Investigator Award from The Heart & Stroke Foundation of Ontario. "The collaborative nature of this multi-centre study, has allowed us to gather valuable information that will be essential in developing and improving treatments for childhood stroke."
The study is the result of the collaboration of 38 Canadian researchers who have formed the Canadian Children's Stroke Network and collaborate in the Canadian Pediatric Ischemic Stroke Registry. The registry includes all 16 paediatric tertiary care centres in Canada.
"We have initiated a specialized clinical and research Children's Stroke Program at SickKids, the first in North America. The Children's Stroke Program works closely with the Children's Thrombosis Service to care for children with strokes due to blood clots such as sinovenous thrombosis. Today, strokes in children appear to be increasing in frequency due to better detection methods and because children now survive previously fatal conditions that can cause strokes, like prematurity, congenital heart disease and leukemia, so research in this area is vital," said Dr. deVeber.
The study has determined that sinovenous thrombosis accounts for 20 per cent of all ischemic strokes in children. The incidence of this disorder in the childhood population is at least one per 200,000 children and 1 in 3000 newborns per year. The other 80 per cent of ischemic strokes are categorized as arterial. Ischemic strokes occur from blockage in the arteries or veins supplying blood flow to the brain, and are most often caused by a blood clot. The other major type of stroke is haemorrhagic and is caused when a blood vessel in or near the brain ruptures.
"The presence of clotting problems underlying sinovenous thrombosis in nearly one third of children in this study is important, since these disorders may cause further clots in affected children," said Dr. Maureen Andrew, the study's co-authour, a paediatric haematologist, senior scientist in the SickKids Research Institute and Professor of Paediatrics at the University of Toronto.
In adults, sinovenous thrombosis has an established acute treatment using blood thinners, making it a potentially treatable condition in children. Presently, researchers are working to understand the effects of treatment using data in the Canadian registry. This information will eventually serve as the basis for the development of international clinical trials for sinovenous thrombosis.
"Studying strokes in children is a unique opportunity to further our understanding of strokes in both children and adults. Children who experience a stroke do not have the usual adult acquired risk factors such as hardening of the arteries, so we can isolate other reasons for stroke more easily. Our long-term outcome study is determining the full extent of damage left by sinovenous thrombosis in children. Children have the ability to recover much more effectively than adults. If we can understand these recovery mechanisms in children we may be able to learn more about adult stroke recovery," said Dr. deVeber.
Funding for this research was provided by The Bloorview Childrens Hospital Foundation, The Heart and Stroke Foundation of Ontario and other grants.
For more information, please contact:
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