Sudden Infant Death Syndrome (SID): Brain Abnormalities Explain Underlying Health Issue

According to researchers at Boston Children's Hospital, infants dying suddenly and unexpectedly in either safe or unsafe environments may have underlying brainstem abnormalities prior to death.

Researchers also point to a need to detect and help treat this underlying health issue early as part of the focus of their current work.

Lead study author Hannah Kinney, MD, a neuropathologist at Boston Children's, has shown over the past two decades how this issue is affected by brain chemistry that set these infants apart from others.

For instance, she mentions abnormalities in the brainstem circuits that impair breathing control, heart rate, blood pressure and temperature control during sleep. Researchers believe that when sleeping babies are prevented from rousing, this can create too much carbon dioxide and cause them to become overheated.

The study often shows that infants who often die a sudden and unexpected death may be found sleeping face down or smothered by their pillow.

Kinney and colleagues reexamined their data by reviewing the cases of 71 infants who died suddenly and unexpectedly. They were autopsied at the San Diego County Medical Examiner's office from 1997 to 2008 and had brainstem samples available for analysis. Researchers grouped the infants based on their sleep circumstances--those considered safe (asphyxia not likely) or unsafe (asphyxia likely) based upon death-scene investigation reports.

At the end of the examination, they compared 15 infants with SIDS whose deaths did not involve asphyxia, 35 SIDS infants whose deaths were possible asphyxia-related and 9 infants who died from other causes.

Various neurological abnormalities were noted-including serotonin, serotonin receptors, GABA receptors and 14-3-3 (a protein that regulates serotonin.)

"Even the infants dying in unsafe sleep environments had an underlying brainstem abnormality that likely made them vulnerable to sudden death if there was any degree of asphyxia," Kinney said, via a press release. "The abnormality prevents the brainstem from responding to the asphyxial challenge and waking."

The investigators believe these findings confirm that sudden unexplained death in infants is associated with underlying vulnerabilities, and that not all infants who die in compromised sleep environments are normal.

"Certainly, there are unsafe sleeping environments that can cause any baby to die, such as entrapment in the crib, but if it's just sleeping face down, the baby who dies may have an underlying brainstem vulnerability," says Kinney. "We have to find ways to test for this underlying vulnerability in living babies and then to treat it. Our team is focused now upon developing such a test and treatment.

"Safe sleep practices absolutely remain important, so these infants are not put in a potentially asphyxiating situation that they cannot respond to."

More information regarding the study can be found via the journal Pediatrics.