Background on SIDS or Crib Death
SIDS stands for sudden infant death syndrome also known as crib death. About 2,500 infants under the age of one, die from SIDS in the U.S. every year according to the National Center for Health statistics.
Visit our SIDS page to learn more.
The cause of sudden infant death syndrome (SIDS) is still one of the great mysteries of medicine that kills thousands of babies a year.
A newly published study is offering a provocative theory on the cause of SIDS. Dr. Daniel Rubens of Children's Hospital and Regional Medical Center in Seattle suggests SIDS babies experience an injury to their inner ears during birth caused by the high-pressure surge of blood from the placenta during delivery. A subgroup of hair cells in the ear, which normally maintain balance, may actually be responsible for transmitting information that regulates breathing.
He found that all babies in a Rhode Island study group who died of Sudden Infant Death Syndrome (SIDS), shared lower hearing levels in their right inner ear when compared to infants who did not have SIDS. The lower hearing levels might suggest that delicate vestibular hairs in the right inner ear were damaged during birth.
In the future, doctors might be able to identify newborns at risk for SIDS by a simple, affordable and routine hearing test administered shortly after birth.
The study is published in the July 2007 journal, Early Human Development. He talked to IB News Editor Jane Akre about his findings.
Dr. Rubens is an assistant professor at the University of Washington and a pediatric anesthesiologist at Children’s Hospital and Regional Medical Center in Seattle. There he created the simulation baby “Sim Baby,” now universally used in his role as a clinical educator to train medical teams to handle scenarios from meningitis to cardiac arrest.
Dr. Rubens Interview
IB: You must be hearing from a lot of parents about this study?
Dr. Rubens: Yes I have. SIDS is one of the greatest medical mysteries because we don’t know what causes it. Alzheimers and cancer for example, we know what causes them but we don’t know what the mechanism is that causes SIDS. Currently, the conventional theory is that there is a mixed bag of etiologies for SIDS. Among medical coroners and lay coroners, they have different levels of experience and the pathologists I have spoken to think that SIDS is under-diagnosed.
IB: Under your hypothesis c-section babies would not die from SIDS because they don’t go through the birth canal?
Dr. Rubens: That’s not quite correct. There may still be a buildup of pressure in the placenta with a c-section. However if a mother has an elective c-section without contractions the likelihood of a SIDS baby may conceivably be much decreased.
IB: How do you measure the hearing of a newborn since they can’t talk?
Dr. Rubens: Newborn screening tests are being used around the country. A practitioner puts a probe in the ear canal when the baby is sleeping and the machine sends off a click to the inner ear. Nerve hair cells are set up along a membrane to determine hearing at various frequencies. The probe sends a click to the hair cells which send back a signal as to whether they are responding or not. It’s a basic and preliminary hearing test.
IB: Why rely on testing on the right side only?
Dr. Rubens: My theory is that the injury occurs on both sides, but this hearing test is only picked up a difference on the right side. The injury may be more widespread on the right side than the left side. If we were to look at higher frequencies on both sides I think we may find that the left side also is also damaged. There needs to be damage to both sides for a baby to die from SIDS. I’m proposing there is more widespread damage on the right side because the high pressure injury to the veins on the right side are in the direct line of fire, more so than on the left.
IB: And what is the course of action if damage is found to the right ear?
Dr. Rubens: The hearing test could be the first test. There could be other signs of injury as well. We may find that when we look at the baby that there are bleeding points in a number of regions in the body if we look closely enough. In time hopefully we will find more markers.
IB: What’s next?
Dr. Rubens: The next phase of research is an animal study to see if damaged hair cells in the inner ear impair the transmission of carbon dioxide information to the brain. Also larger scale hearing tests. I’d also like to develop a computer model of the birthing pressure injury I’m proposing.
At this time, parents should follow established guidelines to prevent SIDS such as to avoid smoking and placing the infant to sleep on their back on a firm surface in a room with good ventilation.
Latest SIDS Research
Early Human Development, July 2007 – This study found all babies in a study group who died of SIDS had a hearing difference in their right inner ear that is proposed by Dr. Rubens, the primary author, to occur at birth and may be responsible for transmitting information concerning carbon dioxide levels that regulates breathing. USA Today reports on Dr. Daniel Rubens of Children’s Hospital and Regional Medical Center in Seattle, one of the authors of the study.
American Academy of Pediatrics, 2006 - Often SIDS is confused with child abuse. This article tells health practitioners how to tell the difference.
American Academy of Pediatrics, 2005 – The policy of the AAP does not recognize side sleeping as a reasonable alternative to back sleeping for infants. Also names the soft objects that should never be in an infants crib including toys, pillows, matress coverings and sheepskins.
American Academy of Pediatrics, 2003 – This published report says that since the 1970’s sleep apnea has been a suspected cause of SIDS. A home monitoring industry responded providing home versions to measure heart-lung response in infants even though AAP says the link between sleep apnea and SIDS has not been established. The AAP discourages the use of home monitoring machines.
American Academy of Pediatrics, Policy Statement, 1998 - This paper examines the rapidly evolving area of research around indoor mold and its link to pulmonary hemorrhaging in infants. Mold can grow on indoor products such as dry wall, paper, carpeting and fabrics and infants spend usually at least 75% of their time indoors.