OT: New Evidence on Main Cause of Cerebral Palsy - infection - {periventricular leukomalacia}
- Subject: OT: New Evidence on Main Cause of Cerebral Palsy - infection - {periventricular leukomalacia}
- Date: Tue, 02 Nov 2004 03:59:52 -0700
- Yahoo! Message Number: 123114
- Onibasu Link: http://onibasu.com/archives/am/123114.html
New Evidence on Main Cause of Cerebral Palsy
By NICHOLAS BAKALAR
http://www.nytimes.com/2004/11/02/science/02infa.html
A new study undermines the long-held belief among obstetricians that
oxygen deprivation, or hypoxia, is the main cause of cerebral palsy in
premature infants.
The study, published in the October issue of The American Journal of
Obstetrics & Gynecology, found that the brain injury that leads to
cerebral palsy was much more commonly associated with infection than
with hypoxia.
The new findings, said Dr. Ernest Graham, an assistant professor in the
department of obstetrics and gynecology at Johns Hopkins and the lead
author of the study, have important implications for both research and
clinical practice.
"This changes our thinking," Dr. Graham said. "In the past, we've
focused primarily on hypoxia," but the study suggests that monitoring
for hypoxia "isn't likely to help very much."
Finding ways to prevent and treat infections, on the other hand, "may
have a huge impact on the problem," he said.
The researchers studied premature infants born from 1994 to 2001 in a
university hospital. They looked at cases of periventricular
leukomalacia, or PVL, a specific kind of damage to the white matter of
the brain. The white matter transmits signals in the brain and from the
brain to the spinal cord, and is particularly subject to injury in
premature infants.
While there are other factors associated with brain damage in premature
infants, like bleeding into the brain and pregnancies in which a woman
carries two or more fetuses, a large majority of infants with PVL
develop cerebral palsy. The symptoms may not be evident for many months
after birth, but the damage can be seen on brain scans, which reveal the
characteristic cysts that form after brain tissue is damaged.
In time, the cysts are reabsorbed, leaving abnormally enlarged
ventricles where the brain tissue has died. PVL can cause a range of
physical and mental disabilities from mild to very severe, but the most
common is spastic diplegia, tightly contracted muscles in the legs that
cannot function normally.
When researchers looked at 150 preterm babies with PVL and matched them
to a control group of 150 preemies born in the same time period who did
not have brain damage, the results were surprising. Hypoxia, as measured
by umbilical cord blood tests, was no more common in the premature
babies with PVL than it was in the other babies.
Delivery by Caesarean section was not associated with PVL, nor did tests
of blood chemistry distinguish injured from noninjured babies. Even
babies whose fetal heart rates were reduced during labor and delivery
were not any more likely than other babies to suffer brain injury.
What did make a difference, and it was a large one, was whether the
babies had suffered infections. Infants who had positive bacterial
cultures of the blood, cerebrospinal fluid or throat were two to four
times as likely to suffer brain damage as those who did not.
Staphylococcus infections predominated, but the researchers found more
than 10 other kinds of infections as well, and the type of infection
made no difference in the rates of injury.
"This is an important and fascinating paper," said Dr. Larry Gilstrap,
chairman of obstetrics, gynecology and reproductive sciences at the
University of Texas Medical School at Houston. Dr. Gilstrap, who was not
involved in the study, noted that with a possible cause for the brain
injuries, methods of preventing them might be found.
*
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