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Biological
Cause Behind Speech Delays
Researchers have found that there may,
in fact, be a biological cause behind speech delays in children.
The issue can be very troubling
for parents, especially because doctors often can't find a cause
that explains the delay.
However, by using functional magnetic
resonance imaging (fMRI), researchers from Miami Children's Hospital
report that youngsters with speech delays often use the right
side of their brain to process language instead of the left. A
report on the findings in the December issue of Radiology.
"This study is important because
it helps us understand why children who have such normal-looking
brains can have language problems," says Dr. Ruth Nass, a pediatric
neurologist from New York University Medical Center in New York
City.
Nass says by using fMRI, the researchers
were able to show that what's important is not just the structure
of the brain, but also where things happen in it.
"This study is saying that the
wiring differences are so large that the wrong side of the brain
is mediating language," Nass notes.
"The left hemisphere is supposed
to be the language center from the get-go," she explains. "If
there's something different in how your brain is wired, [the language
center] ends up being on the right. Your brain can still [process
language], but not as well."
For the study, Miami Children's
Hospital researchers recruited 17 children with speech delays
and 35 children with normally progressing speech to act as controls.
All of the children were between the ages of 2 and 8 years old.
Each child had previously undergone
standard MRI scans, and their brain structure was found to be
normal.
To assess brain function, the children
were sedated and then the researchers completed fMRI scans of
the youngsters as audiotapes of their mothers' voices played in
the background. The researchers were able to get useful scans
in 25 of the 35 control children and in 11 of the 17 youngsters
with speech delay.
Dr. Arthur Kenney, a radiologist
at Ochsner Clinic Foundation Hospital in New Orleans, explains
that fMRI is a way of looking at which areas of the brain receive
more oxygen when performing a specific task. For this study, he
says, the task was passive listening.
"If a person is listening to a
tape of someone talking, there's increased oxygen delivery, usually
to the left temporal lobe," Kenney adds. That increased oxygen
delivery shows up on an fMRI scan and is referred to as "activation."
Activation occurred on the left
side of the brain for 52 percent of the control children and on
the right side of the brain in 64 percent of the children with
speech delays. When the researchers looked just at children older
than 3, the difference was more pronounced: 83 percent of those
with speech delays showed activation on the right side, while
71 percent of the controls showed activation on the left.
Although intrigued by the study's
findings, both Nass and Kenney say they don't see any immediate
practical implications from these findings.
"Were probably getting closer to
finding an anatomic cause of speech delay," says Kenney.
Nass adds, "Parents need to know
that there are real biological causes for late language, and this
may not be the only one. We need to investigate further in order
to come up with better remediation treatments or preemptive methods,
but those are far off."
More information
To learn more about fMRI, visit
the Radiological
Society of North America.
Reference
Source 101
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