Researchers identified 2,278 first admissions for childhood stroke in a 10-year period in California by examining a statewide hospital discharge database. Children were one month through 19 years of age and were classified by their parent or guardian as white, black, Hispanic, Asian or other. Boys made up 51 percent of the population, and girls made up 49 percent.
Ischemic stroke (the most common type of stroke, resulting from blocked arteries) accounted for 51 percent of the cases. Hemorrhagic stroke accounted for the rest, and was broken down into intracerebral hemorrhage (vessels bleed into the brain) and subarachnoid hemorrhage (abnormal vessels rupture near the membrane surrounding the brain). The annual stroke incidence rate was found to be 2.3 strokes per 100,000 children.
"Adult stroke risk is well documented, but little is known about childhood stroke," said study author Heather J. Fullerton, MD, a pediatric stroke neurologist at the University of California, San Francisco. "A lot remains to be understood."
Boys were found to be 28 percent more likely than girls to have a stroke of any type. More than 4 percent of all stroke cases also had head trauma, which is a risk factor for childhood stroke. Boys were almost twice as likely to have a diagnosis of trauma. Yet after excluding cases with trauma, boys still had an increased risk for ischemic stroke. This suggests that other factors contributed to the higher risk in boys, Fullerton noted.
Black children had more than twice the risk of stroke overall. Asian children had similar risks as white children for all stroke types. Hispanic children had the lowest risk for ischemic stroke and intracerebral hemorrhage.
Nearly 7 percent of the ischemic stroke cases also had sickle cell disease (a blood disorder affecting the red blood cells), which is another known risk factor for childhood stroke. In black children who had an ischemic stroke, more than 38 percent also had sickle cell disease. After excluding cases with sickle cell disease, however, black children still had a 61 percent increased risk of stroke. This suggests that sickle cell disease does not completely explain why black children are having more strokes, Fullerton said.
Previous studies have shown that adult males have higher rates of ischemic stroke and intracerebral hemorrhage. Likewise, black adults have been shown to have a higher risk of stroke. These findings have been explained by the higher rates of stroke risk factors (smoking, diabetes and hypertension) in these groups.
"These explanations cannot be used to account for our findings because risk factors like hypertension and smoking do not play a significant role in childhood stroke," Fullerton said. "Additional population-based studies are needed to explore unrecognized risk factors like genetic predisposition or unidentified environmental risks, and shed light on why children have strokes."
The study also found that infants one month to one year old had the highest rates of any age group for ischemic stroke and intracerebral hemorrhage. Teens 15 through 19 years old were found to have the highest rates of subarachnoid hemorrhage.
The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.
For more information about the American Academy of Neurology, visit its website at http://www.