According to Laura R. Ment, MD, Yale University School of Medicine, an author of the guidelines, "Survival rates have steadily increased among babies born early or with low birth weight. Unfortunately, the incidence of cerebral palsy has not declined in 10 years, and the population of infants at risk is growing. Neuroimaging of the developing brain has become an important tool for diagnosing, decision-making, and evaluating treatment effectiveness."
Although neuroimaging has proven to be extremely helpful for the assessment of injury to the preterm infant's brain, and may provide useful information for evaluating the infant with neonatal encephalopathy, there are significant problems associated with imaging of the critically ill infant.
"The choice of imaging technique, the timing of the imaging study, and regional variations in maturation of the developing brain all factor into the best use of neuroimaging," said Ment.
Briefly, the recommendation states that all preterm neonates born under less than 30 weeks gestation should receive screening cranial ultrasonography (US) once they are between 7 and 14 days old, and the screening should be repeated when they have reached 36 to 40 gestational weeks. The screening is recommended to detect lesions such as major hemorhages or white matter damage that might affect the infant's neurodevelopment. There is little evidence to support routine MRI of all very low birth weight preterm infants with abnormal results from the cranial US testing.
When a full term infant with coma or seizures has evidence of birth trauma, CT should be performed to detect any hemmorrhages. If the CT findings do not demonstrate bleeding in the baby's brain, then an MRI should be performed when the infant is between 2 and 8 days of age to look for evidence of hypoxic-ischemic injury to the developing brain, since this is a major cause of cerebral palsy in term infants, said Ment.
The panel of neonatlogists, pediatric neurologists, perinatal epidemiologists, and neonatal radiologists developed the recommendations after reviewing more than 1,300 articles published since 1990. Only 90 reported data from studies that met the rigid criteria to be included in the guidelines development.
Newer imaging technologies such as near infrared spectroscopy, nuclear medicine and fMRI were not included in the recommendations because there is not yet enough data to assess their use in brain imaging.
The American Academy of Neurology, an association of 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its web site at www.aan.com.