Vascular Imaging Key to Predicting Repeat Childhood Stroke

May 02, 2007
News Office: Phyllis Brown (415) 502-6397

One of the first major studies of pediatric stroke has revealed that as many as one fifth of children who have had strokes are at risk of a recurrence, and that recurrence can be predicted accurately through the use of cerebrovascular imaging techniques commonly employed to diagnose adults but inconsistently prescribed for children.

Stroke has increasingly been recognized as a significant cause of childhood physical and mental disability, but few studies have been conducted to examine the risk and predictors of recurrence of strokes in children.

In the March issue of the journal "Pediatrics," a UCSF-led team found that strokes recurred in almost 70 percent of the children whose vascular imaging studies identified abnormalities, but there was no recurrence of stroke in those children with normal vascular imaging.

Although there currently are no guidelines for the diagnostic evaluation of pediatric stroke patients, techniques for imaging the blood vessels to the brain, such as magnetic resonance angiography (MRA), should be standard practice for childhood stroke sufferers, according to the authors. In addition, they say, because the study found the likelihood of recurrence of stroke in children, steps can be taken to prevent them such as prescribing antithrombotic medications and surgical interventions.

"Our data demonstrates that these imaging studies can identify those children at highest risk for recurrence with a high rate of accuracy," said the lead author, Dr. Heather Fullerton, assistant professor of neurology and pediatrics and director of the Pediatric Stroke Center at UCSF Children's Hospital. "Identification of a child at high risk for recurrence on the basis of vascular imaging not only provides prognosis but also an opportunity for risk reduction," the study says.

Stroke, also known as a cerebrovascular accident (CVA), occurs when the blood supply to any part of the brain is interrupted. It can result in brain tissue death and the loss of brain function. If blood flow is interrupted for longer than a few seconds, brain cells can die, causing permanent damage. Arterial ischemic stroke may be caused by a blood clot that forms in the brain (a thrombus) or a blood clot, piece of plaque, or other material that travels to the brain from another location (an embolism). The resulting stroke-related symptoms depend on the area of the brain affected, the extent of the damage and the cause of the stroke. The study did not examine patients who had experienced hemorrhagic stroke, caused by the bleeding of ruptured blood vessels in the brain.

The retrospective study examined all cases of stroke occurring within the population of children less than 20 years old who were enrolled in the Kaiser Permanente Medical Care Program in Northern California during the 11 years between January 1993 and December 2003; a total of more than 2.3 million children. Some 181 cases of childhood arterial ischemic stroke were confirmed in that population. Eighty-four cases, or 46 percent, were perinatal, occurring before birth; 97 cases, or 54 percent, occurred later in childhood.

The vast majority of the 97 children who had strokes later in childhood had first-time strokes. Only three of the children had strokes prior to the study period or enrolling in the Kaiser Permanente Medical Program. Fifteen of the children who had strokes later in childhood had a recurrent stroke. Thirteen of those 15 children who had recurrent strokes also received vascular imaging. Abnormal vascular imaging predicted recurrence. None of the children with normal vascular imaging had a recurrent stroke, whereas nearly two thirds of those with vascular abnormalities suffered a recurrence within five years.

Abnormalities included known entities such as arterial dissection (a tear in the wall of a blood vessel), moyamoya (a rare childhood syndrome in which blood vessels narrow over time), and vasculitis (inflammation of the blood vessels). However, the majority of children had a focal area of stenosis (narrowing) of a blood vessel, with no apparent cause.

"Cerebrovascular imaging, although commonly performed in the evaluation of an adult stroke patient, often is not performed in children with arterial ischemic stroke," the researchers write in their paper. "Slightly under half of the cases in our study had such imaging, and there was no change in rates of vascular imaging over the 11 years of the study...However, our data demonstrate that these imaging studies can identify those children at highest risk for recurrence: By 5 years recurrent strokes occurred in none of the children with normal vascular imaging, compared with almost 70 percent of children with vascular abnormalities."

The researchers reported that, although there have been no randomized, controlled trials of secondary stroke prevention in children "a variety of strategies are used to reduce the likelihood of a recurrent stroke in the setting of specific high-risk vascular abnormalities." Those strategies include medical therapy, such as the use of antithrombotic agents (such as aspirin), as well as surgical interventions, such as vascular bypass procedures.

Other study authors include Dr. Yvonne W. Wu and Dr. Claiborne S. Johnston, of the University of California, San Francisco, and Dr. Stephen Sidney, of the Kaiser Permanente Division of Research in Oakland, California. The study was funded by an American Heart Association Scientific Development grant and National Institute of Neurological Disorders and Stroke Neurological Sciences Academic Development Award.

One of the nation's top children's hospitals, UCSF Children's Hospital creates an environment where children and their families find compassionate care at the healing edge of scientific discovery, with more than 150 experts in 50 medical specialties serving patients throughout Northern California and beyond. The hospital admits about 5,000 children each year, including 1,600 babies born there.

The University of California, San Francisco is a leading university that advances health worldwide by conducting advanced biomedical research, educating graduate students in the life sciences and health professions, and providing complex patient care.

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