(TOLEDO, Ohio) -- Six-year-old Erica Wilcox woke up one fall morning in 2011 and told her parents her right hand felt "fizzy."
The first-grader was healthy and active, even running cross-country at her elementary school, so her parents, Dan and Leann Wilcox, of Toledo, Ohio, didn't think much of it.
"Honestly, we kind of wrote it off as her just sleeping on her arm wrong," Dan Wilcox said.
They had no idea their young daughter had had a stroke.
"If you would have told me when I was watching her run on the track that a few days later I'd be taking her to the hospital for a stroke, I'd have never believed it," Wilcox said. "But there were warning signs there."
Many people hear "stroke" and think only older adults, perhaps with heart disease or other underlying conditions, are stricken. But children can also suffer from strokes, although they are rare. Doctors estimate that about six out of 100,000 children have a stroke each year. Stroke is one of the top 10 causes of death for children in the U.S.
The cause of Erica's stroke made it even more unusual. Erica has Moyamoya, a rare condition in which the vessels feeding blood to the brain become narrowed over time as the walls of the arteries get thicker. Sensing the lower flow of blood, the body will try to compensate by sprouting new webs of smaller blood vessels to bypass the blockage, creating what the Japanese call Moyamoya, meaning "puff of smoke," on brain imaging scans.
Moyamoya primarily affects children and teens, who are usually unaware that their arteries are silently narrowing, choking off blood to their brains. Dr. Mark Bain, a neurosurgeon at the Cleveland Clinic, said often the condition is diagnosed only when a child comes to the hospital after having a stroke.
"A lot of times, the signs will be very subtle, like numbness or tingling in the limbs," Bain said. "It's such a rare thing to have a stroke in children that a lot of the time, people don't diagnose it right away."
Weeks after Erica awoke with "fizziness" in her hand, Leann Wilcox was helping Erica with her homework, and noticed that she was using her left hand to write, even though she was right-handed. When Wilcox asked her to hold her pencil in her right hand, Erica said she couldn't. Hours later, Erica told her parents that she couldn't put her clothes on after taking a shower. By the time the Wilcoxes got to the hospital 10 minutes from their home, Erica couldn't move her lower arm at all.
"It was unbelievably scary," Dan Wilcox said.
Wilcox said Erica's doctors were initially perplexed and, spotting the "puff of smoke" blood vessels on her brain scans, thought that she had a brain tumor. But more tests revealed Erica's stroke and Moyamoya.
Doctors understand very little about the causes of Moyamoya, although a genetic basis for the disease is suspected. Bain said blood-thinning drugs like aspirin can be a short-term solution, but ultimately the best solution is surgery to try to restore the brain's blood flow.
Copyright 2012 ABC News Radio