Cerebral Palsy Risk Linked to Early Virus Exposure

Australian researchers find previously unknown connection

THURSDAY, Jan. 5, 2006 (HealthDay News) -- Exposure to neurotropic viruses like herpes shortly before and after birth can heighten a baby's risk of developing cerebral palsy, Australian researchers report.

According to the researchers, these findings add weight to the theory that infections can trigger brain damage and the development of cerebral palsy.

The report appears Thursday in the online edition of the British Medical Journal.

"This research underlines the fact that yet another antenatal cause of cerebral palsy has been identified, and provides further evidence that cerebral palsy is very rarely caused by events during labor," said lead author Catherine Gibson, a postdoctoral research fellow at the University of Adelaide.

"We are gaining more understanding of the pathology and mechanisms behind the development of cerebral palsy," Gibson added. "And with this understanding, we may be able to prevent some cases of cerebral palsy in the future, for example through vaccinations against infectious agents."

In its study, Gibson's team collected data on 443 children with cerebral palsy, comparing them with 883 infants who didn't have the condition.

Gibson's group took blood samples a few days after the children's birth to test for the neurotropic viruses. These viruses include herpes viruses, which can cross the placenta and infect the fetus.

They found that exposure to viral infection was common in all newborn babies, especially in preterm babies. Particularly, herpes group B viruses were found more often in babies later diagnosed with cerebral palsy compared with babies who didn't develop cerebral palsy.

"The risk of cerebral palsy was nearly doubled with exposure to certain herpes viruses, including the chicken-pox virus," Gibson said. "In addition, the presence of cytomegalovirus was associated with preterm delivery in babies without cerebral palsy."

One expert thinks that while the findings are important, a lot remains to be explained about exactly how the viruses cause cerebral palsy.

"This paper describes a previously unrecognized association between herpes virus exposure and cerebral palsy," said Dr. Yvonne Wu, an assistant professor of neurology and pediatrics at the University of California, San Francisco. "This finding is exciting and provocative," she added.

The cause of cerebral palsy, a group of disorders that affect body movement and muscle coordination, remains poorly understood, although it is believed to start in the brain before or around birth.

Perinatal infection and inflammation have been thought to play a role in some cases, Wu said. "The findings in this paper support this notion and may lead to a better understanding of what underlies the brain injury that leads to cerebral palsy," she said.

"It is important to remember that although these findings may help us better understand the complex processes leading to cerebral palsy, the viruses linked to cerebral palsy in this study are commonly present, and only increase the risk of cerebral palsy by a very small degree," Wu said. "It is also unknown how exposure to these viruses could cause brain injury in the infant or fetus."

Another expert noted that viral infections have been known as causes of cerebral palsy for some time.

"We need a lot of help in understanding what may be the causes of cerebral palsy," said Dr. Karin Nelson, a senior investigator at the U.S. National Institute of Neurological Disorders and Stroke. "And this may be part of the answer."

In addition, it may be possible to prevent some cases of cerebral palsy by vaccinating women against certain viruses, Nelson said.

Nelson cautioned that this latest research should not cause parents to panic. "Although viruses can play some role, there seems to be something else going on that would explain why only a small proportion of people with some exposure to the virus actually end up with babies who get disabling troubles," she said.

More information

The National Institute of Neurological Disorders and Stroke can tell you more about cerebral palsy.

SOURCES: Catherine Gibson, Ph.D., postdoctoral research fellow, University of Adelaide, Australia; Yvonne Wu, M.D., M.P.H., assistant professor of neurology and pediatrics, University of California, San Francisco; Karin Nelson, M.D., senior investigator, National Institute of Neurological Disorders and Stroke, Bethesda, Md.; Jan. 5, 2006, online edition British Medical Journal
Consumer News