(From the November 2013 Issue of PediatricsOnline)
Long-term outcomes for children who have experienced an arterial ischemic stroke are often uncertain. Recovery is believed to depend on stroke severity, timing of treatment and initiation of appropriate therapy. New research by a team at Nationwide Children’s Hospital suggests that these outcomes are even more complex in origin than previously thought.
The study, published in the June issue of the Journal of Child Neurology, found lingering effects of stroke may have the same kind of impact on future cognitive function as other pediatric chronic illnesses—even those that don’t directly involve the brain. The research could help physicians better understand the after effects of pediatric stroke, a leading cause of death in children in the U.S.
“Impaired cognitive function has been known to be a complication of stroke, however, it has been difficult to identify which children have the greatest risk,” says Warren D. Lo, MD, a senior author on the new study and director of the Stroke and Vascular Anomalies Clinic at Nationwide Children’s. “This study and others in stroke survivors will help identify those who are at greatest need for intervention so we can improve the outcomes of these children.”
Unlike previous research on the topic, this new study compared children with a prior arterial ischemic stroke to children with asthma. The study was the first to include a comparison group comprised of children with a chronic illness not affecting the central nervous system, a distinction that allowed the researchers to determine how stroke affects cognitive outcome compared to chronic illness in general.
“Chronic illness itself may have effects on cognitive function that do not necessarily require a central nervous system insult,” says Christine Hajek, PhD, a postdoctoral researcher at Nationwide Children’s Hospital and lead author of the study. “Our data suggest that lower cognitive scores among children with stroke are likely related to the combination of neurological impairment following stroke and the presence of chronic stroke-related illness.”
The causes, symptoms and treatments of stroke are strikingly different in children than in adults. And yet, the majority of research on stroke has historically involved only adults. The need for a more focused look at pediatric stroke—both at the bedside and the bench—was one of the motivating factors for the development of the Stroke and Vascular Anomalies Clinic at Nationwide Children’s, one of the first programs of its kind in the country. In addition to providing comprehensive care to patients, clinic members also conduct research on pediatric stroke and participate in the International Pediatric Stroke Study and other multi-institutional studies.
For this study, researchers at Nationwide Children’s collaborated with faculty at Royal Children’s Hospital in Melbourne, Australia. The team enrolled 51 participants up to 14 years of age who had suffered a stroke. They examined stroke lesion location and volume to determine whether these factors could predict cognitive outcomes following a stroke. Both groups of children then completed a series of pediatric cognitive performance tests to compare cognitive abilities.
The approach offered some new insights. “We expected both stroke severity and lesion volume to be related to cognitive outcome, but this was not always the case,” says Dr. Hajek. Greater stroke severity and lesion volume resulted in lower cognitive scores only in certain functional categories. Both study groups scored significantly lower on the cognitive tests than the normative population, but the stroke group scored only slightly lower overall than the asthma group.
These findings point to the need for more in-depth analysis of the effects of stroke on general cognitive outcome, social outcome, and verbal and nonverbal functioning, the researchers say. The published study was part of a larger project in which she and her colleagues collected data to examine social and cognitive outcomes after stroke.
By gaining a better understanding of the biological mechanisms and predictive factors at play in the recovery process, it may be possible to improve the treatment and rehabilitation of these patients, Dr. Hajek notes. “In a clinical setting, assessment of clinical and neuropsychological functioning is imperative to determine which children are exhibiting stroke-related deficits and need accommodations at home or at school.”
Despite the noted difficulties faced by children with stroke, few intervention programs have been developed for this population. Given the cognitive, behavioral and adaptive challenges children may face following a stroke, development of effective rehabilitation programs is necessary, Drs. Lo and Hajek say. Interventions in this population are difficult to generalize, however, because the outcomes of stroke are variable and depend on a variety of factors. This, they add, highlights the need to continue examining predictors of cognitive outcome to determine which groups of children will benefit most from effective intervention programs.
Hajek CA, Yeates KO, Anderson V, Mackay M, Greenham M, Gomes A, Lo W. Cognitive Outcomes Following Arterial Ischemic Stroke in Infants and Children. Journal of Child Neurology. 2013 Jun 11. [Epub ahead of print]