An important number of infants who died of SIDS (Sudden Infant Death Syndrome) suffered a brain abnormality in the hippocampus, according to a study. The hippocampus is the part of the brain that controls basic functions such as breathing, body temperature, and heart rate.
Sudden Infant Death Syndrome is a diagnostic doctors put in cases where no medical explanation has been discovered after post-mortem investigations. Medical examiners look at the infant’s medical condition, at the death scene and they take family history into account before suggesting this diagnostic. SIDS, which mostly occurs during the baby’s sleep periods, is the main cause of death for infants between one and 12 months in the U.S.
Researchers led by Hannah Kinney, a professor of pathology at Harvard Medical School in Boston, looked at more than 150 infants who died between 1991 and 2012. More than half of the infants had died in a sudden and unexpected way, while the others died because of infections, accidents, homicide or asphyxiation.
Kinney’s team observed the abnormality called focal granule cell bilaminationin, a double layer of cell nerves where there was supposed to be only one layer, in more than 40 percent of the cases, or 43 out of 87 cases. However, they have no clear idea about how this characteristic might have led to the infants’ deaths and stress that correlation does not imply causation. In cases where infants had known causes of death, the abnormality rate was 7 percent.
“The pattern of abnormal changes in the dentate gyrus suggests to us there was a problem in its development at some point in late fetal life or in the months right after birth,” Dr. Kinney said. “We didn’t see any signs of injury to the brain by low oxygen levels in the tissue we examined, such as scarring and loss of nerve cells.”
Some people who suffer from temporal lobe epilepsy exhibit the same abnormality, researchers note in their study.
The abnormality can only be observed under the microscope, so there is no way to test an infant for it. Moreover, infants who develop the hippocampus abnormality do not exhibit any symptoms and there is now way to predict its occurrence. Kinney says that parents should follow the sleep recommendations of the American Academy of Pediatrics, which are still valid.
The study was published online in Acta Neuropathologica.