Right's Wrong for Speech Development

Kids with delays use wrong side of brain to process language

TUESDAY, Nov. 25, 2003 (HealthDayNews) -- 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. For more information on speech delays, go to the American Academy of Family Physicians.

SOURCES: Ruth Nass, M.D., pediatric neurologist, New York University Medical Center, and professor of clinical neurology, New York University School of Medicine, New York; Arthur Kenney, M.D., radiologist, Ochsner Clinic Foundation Hospital, New Orleans; December 2003 Radiology
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