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Ed Note:
The following is a press release from Children's Hospital Boston.
October 3, 2005 -- Higher cognitive functions, like language and visual
processing, have long been thought to reside primarily in the brain's
cerebrum. But a body of research in premature infants at Children's Hospital
Boston is documenting an important role for the cerebellum – previously
thought to be principally involved in motor coordination – and shows that
cerebellar injury can have far-reaching developmental consequences.
The latest study, in the October issue of Pediatrics, also demonstrates that
the cerebrum and cerebellum are tightly interconnected. Sophisticated MRI
imaging of 74 preterm infants' brains revealed that when there was injury to
the cerebrum, the cerebellum failed to grow to a normal size. When the
cerebral injury was confined to one side, it was the opposite cerebellar
hemisphere that failed to grow normally. The reverse was also true: when
injury occurred in one cerebellar hemisphere, the opposite cerebral
hemisphere was smaller than normal.
"There seems to be an important developmental link between the cerebrum and
the cerebellum," says Catherine Limperopoulos, PhD, in Children's Department
of Neurology, the study's lead author. "We're finding that the two
structures modulate each other's growth and development. The way the brain
forms connections between structures may be as important as the injury
itself."
As neuroimaging becomes more sophisticated, cerebellar injury is
increasingly recognized as a complication of premature birth. Improved
survival of fragile preemies, coupled with a surge in premature births, has
left more and more families to deal with the damage to their babies' brains
– including cerebellar damage.
In March, Limperopoulos and colleagues published a study in Pediatrics
showing that the cerebellum grows rapidly late in gestation – much faster
than the cerebral hemispheres – and that premature birth arrests this surge
in development. In another study, published in Pediatrics in September, they
found that the incidence of cerebellar hemorrhage in extremely premature
infants rose significantly, by about 44 percent a year, from 1998 through
2002 – an increase they attribute to improved survival and improved
diagnostic techniques. By 2002, cerebellar hemorrhage was identified in 15
percent of surviving infants weighing less than 750 grams.
"Until recently, cerebellar injury was underrecognized," says Limperopoulos.
"Doctors downplayed it, saying, 'Oh, maybe Johnny will be a little clumsy.'
Our research has made us aware that cerebellar injury is not a benign
finding. We now know to look for it, and can counsel families that their
children are likely to have deficits that extend beyond motor, and that may
benefit from early intervention."
A study presented mid-September, at the American Academy of Cerebral Palsy
and Developmental Medicine meeting, documents the magnitude of these
problems. Limperopoulos and colleagues compared 31 toddlers, born
prematurely and identified at birth as having cerebellar hemorrhage (but no
cerebral injury) with 31 controls who were also born prematurely, but whose
brain imaging studies were normal. In addition to motor problems, over half
the children with cerebellar injury had functional limitations in daily
living, communication, and socialization skills, compared with only 3
percent of controls. Sixty-one percent, versus 3 percent of controls, had
global developmental delays. Deficits included delays in both expressive and
receptive language, visual reception delays, and impaired social and
behavioral function.
Limperopoulos and colleagues continue to follow children who were identified
at birth as having cerebellar injury. The children undergo a battery of
wide-ranging developmental tests including assessment of motor, cognitive,
language, social and behavioral skills and tests of functional abilities in
self-care and day-to-day activities. Comprehensive MRI studies are paying
particular attention to structural connections between the cerebrum and
cerebellum – how the nerve fibers run and connect, and where they might be
disrupted.
"We want to understand what happens over time," Limperopoulos says. "The way
the brain adapts and reorganizes after injury may be the best indicator of
how a child will do."
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Children's Hospital Boston is home to the world's largest research
enterprise based at a pediatric medical center, where its discoveries have
benefited both children and adults since 1869. More than 500 scientists,
including eight members of the National Academy of Sciences, nine members of
the Institute of Medicine and 10 members of the Howard Hughes Medical
Institute comprise Children's research community. Founded as a 20-bed
hospital for children, Children's Hospital Boston today is a 347-bed
comprehensive center for pediatric and adolescent health care. Children's
also is the primary pediatric teaching affiliate of Harvard Medical School.
For more information visit:
http://www.childrenshospital.org/research/.
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