Infection Key in Brain Injury to Preemies

Study finds it plays larger role than lack of oxygen

MONDAY, Oct. 25, 2004 (HealthDayNews) -- Infections that occur in premature newborns play a larger role in causing brain injury than does a lack of oxygen, new research suggests.

The finding is important, since the type of brain injury studied often leads to cerebral palsy.

In the past, experts have assumed that a lack of oxygen, or hypoxia, at birth in preemies leads to a condition known as periventricular leukomalacia (PVL), in which small, cyst-like regions of white matter die, explained study author Dr. Ernest Graham, an assistant professor in maternal-fetal medicine at Johns Hopkins School of Medicine.

PVL, the most common type of premature newborns' brain injury, leads to cerebral palsy in 60 percent or more of those who live to adulthood.

Based on his study, appearing in the Oct. 25 online issue of the American Journal of Obstetrics and Gynecology, "a lot more of these brain injuries may be related to infection rather than hypoxia," Graham said.

The findings suggest that doctors delivering premature infants, defined as those who are delivered more than three weeks before the due date, should not only make sure the newborn has enough oxygen but to look closely for signs of infection, he said. "We might have a lot more impact in avoiding the white matter brain injury by paying attention to the infections and treating them promptly."

Graham and his colleagues analyzed the records of 150 cases of white matter injury in premature infants born at Hopkins from 1994 through 2001. They evaluated the rates of PVL, assessed by ultrasound at three different times after birth, and looked to see if lack of oxygen was noted. Then they compared the brain injury cases with control cases without brain injury.

A very small portion of cases with brain injury also had a condition called metabolic acidosis, which indicates a lack of oxygen. But they found a twofold-to-fourfold increase in the rates of PVL injury among those babies with an infection. The type of infection did not matter, as more than a dozen different kinds of bacteria were identified.

"This shows an association between infection and PVL," Graham said. "Instead of looking at cerebral palsy, which [typically] isn't diagnosed until age 2 or so, we looked at PVL [injury]," he said.

PVL, he said, is typically diagnosed within 30 days of birth by using ultrasound, MRI scans or CT scans of the infant's brain.

The new study adds to the understanding of infection and brain injury, said Dr. Richard Polin, a professor of pediatrics at the College of Physicians and Surgeons at Columbia University in New York. "The cause of brain injury in premature babies is complex," he said, "and infection -- both before and after birth -- may contribute."

Avoiding preterm labor can reduce the risk of newborn infection, Polin said, but that's often out of the mother's control. Only about half of women who have preterm labor are in any known risk group, such as giving birth prematurely to another child, according to the March of Dimes.

More information

To learn more about premature birth, visit the March of Dimes.

SOURCES: Ernest Graham, M.D., assistant professor, maternal-fetal medicine, Johns Hopkins School of Medicine, Baltimore; Richard Polin, M.D., professor, pediatrics, College of Physicians and Surgeons, Columbia University, New York City; Oct. 25, 2004, American Journal of Obstetrics and Gynecology online
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