A new study suggests that many
infants dying suddenly and unexpectedly in all kinds of sleep
environments have underlying brainstem abnormalities.
The researchers, led by Hannah Kinney, professor of pathology at
Harvard Medical School and Boston Children’s Hospital, also point to the
need to detect and treat this underlying vulnerability early. They
report their findings in the December issue of Pediatrics.
The investigators have shown over the past two decades that infants
who die suddenly, unexpectedly and without explanation— whose deaths
are generally attributed to sudden infant death syndrome (SIDS)— have
differences in brainstem chemistry that set them apart from infants
dying of other causes.
These abnormalities impair brainstem circuits that help control
breathing, heart rate, blood pressure and temperature control during
sleep and, the researchers believe, prevent sleeping babies from rousing
when they rebreathe too much carbon dioxide due to inadequate
ventilation, breathe too little oxygen or become overheated from
overbundling.
At the same time, epidemiologic studies have shown that infants
dying suddenly and unexpectedly are often found sleeping face down with
their face in the pillow, or sleeping next to an adult in a
bed—environments that have the potential to lead to smothering and death
by asphyxia.
In the new study, Kinney and colleagues asked if all these infants
are truly normal. They re-examined their data, reviewing the cases of 71
infants who died suddenly and unexpectedly, were autopsied at the San
Diego County Medical Examiner’s office from 1997 to 2008 and had
brainstem samples available for analysis. The researchers grouped the
infants according to sleep circumstances— those that were considered
likely to generate asphyxia and those that were not— based upon
death-scene investigation reports.
In the end, they compared 15 infants with SIDS whose deaths were
deemed not to involve asphyxia (group A), 35 infants with SIDS whose
deaths were possibly asphyxia-related (group B) and 9 infants who
clearly died from other causes (controls). They excluded the other
infants for either insufficient data or evidence of other clear risk
factors for death, such as exposure to drugs or extremes of temperature.
Brainstem neurochemical abnormalities involving serotonin,
serotonin receptors, GABA receptors and 14-3-3 (a protein that regulates
serotonin) were found in both group A and group B. Infants in these two
groups had the same brainstem abnormalities, even though group A had no
environmental risk factors for asphyxia. Both groups had significant
biochemical differences from the controls.
“Even the infants dying in a potentially asphyxia-generating
situation had an underlying brainstem abnormality that likely made them
vulnerable to sudden death if there was any degree of asphyxia,” Kinney
said. “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 compromised 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,” said 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.”
Kinney emphasized that the government’s “Safe to Sleep” campaign
(formerly called “Back to Sleep”) has saved thousands of infant lives,
and has likely included vulnerable babies.
“Safe sleep practices absolutely remain important, so these infants
are not put in a potentially asphyxiating situation that they cannot
respond to,” she said.
Funders of the study include the National Institutes of Health,
First Candle, the CJ Foundation for SIDS, the Jacob Neil Boger
Foundation for SIDS, the Marley Jaye Cerella Foundation for SIDS,
River’s Gift and the Intellectual and Developmental Disabilities
Research Center at Boston Children’s Hospital.
Thank you for posting this. Marley Jaye Cherella's parents live down the street from us. They have raised over $100,000 for SIDS research. Imagine a world where parents don't have to worry about SIDS. I worried about it from the second Max was born and we lost him anyway. The research has been showing that perhaps there was nothing that could have been done for our boys. I wonder if that alleviates the guilt somewhat for you. It helps to alleviate some of mine some of the time.
ReplyDeleteThis is the same explanation and by the far the best explanation I received after we lost Jayden. There was a very similar study conducted in Germany and it found the same results. I know one day we will have a world where we wouldn't worry about SIDS. Thank you for writing this is very well explain.
ReplyDelete