Four of five newborn infants who experience a stroke around the time of birth will develop neurologic disorders such as cerebral palsy, epilepsy, or language delay, according to a study published online July 11, 2005, in the Annals of Neurology.
"Previous studies suggested that approximately half of all infants with stroke at or near the time of birth have a normal outcome," said senior author Yvonne Wu, MD, MPH, a child neurologist at the University of California, San Francisco (UCSF). "We report a higher rate of significant long-term neurologic impairment."
This is the first study of neurologic outcomes following perinatal arterial stroke that includes all infants diagnosed within a large population. Researchers at UCSF and their collaborators at the Northern California Kaiser Permanente Medical Care Program examined the medical records of more than 199,000 children born within the managed care program between 1997 and 2002.
The overall rate of strokes during labor and delivery, or in the month after birth, was about 1 in 5,000 live births. However, the authors note that the study likely missed some cases, since strokes must be confirmed by brain imaging, a procedure that some children with subtle neurologic symptoms do not undergo.
The most common disability, found in 58 percent of perinatal stroke survivors, was cerebral palsy, a catch-all category that describes children with problems ranging from clumsy movement to severe weakness that may confine children to wheelchairs.
"Not surprisingly, we found that a larger extent of brain injury, and injury to specific areas of the brain that control movement were both factors that increased the risk of cerebral palsy," said Wu.
Other abnormal outcomes included epilepsy (39 percent), language delay (25 percent), and behavioral abnormalities such as hyperactivity (22 percent).
An interesting finding was that cerebral palsy was more likely to occur in infants who had no symptoms early in life. In such cases, the stroke was typically discovered months after birth when the child was noted to have diminished use of one hand. These children were more likely to have sustained injury to deep structures of the brain that control movement.
The cause of stroke in babies is poorly understood, and is currently under investigation in several ongoing large studies of newborn stroke in the U.S., Canada, and Europe.
"Our data do not directly impact the current treatment of perinatal stroke," said Wu. The authors did not find a single case of stroke recurrence, supporting the argument that these children should not be placed on prophylactic anti-stroke medicines.
"However, we hope to raise awareness of this disorder," said Wu. "Infants with unexplained seizures or weakness on one side of the body should be evaluated by a neurologist, and should receive a head imaging study to evaluate for perinatal stroke."