Close to finding the cause of SIDS?

There’s great news from Seattle about a potential cause of one the the cruellest medical mysteries: sudden infant death syndrome (SIDS).
It may be related to an undetected, inner-ear dysfunction that makes it difficult for a baby to automatically rouse and reposition itself when it is having trouble breathing.

SIDS, or cot death as it used to be known, is one of those dreadful things parents and professionals worry about and hope will never happen. It typically occurs with babies under the age of one year who lack the ability to readjust themselves should they struggle to breathe. I only encountered one such death during my professional career but have never forgotten it, or the parents’ anguish. Years later, they remained perplexed, wondering whether it was something they did that led to or caused their child's death.

In the United States, SIDS remains the cause of around 4,000 deaths a year. Fortunately, there are fewer and fewer cases in England and Wales now - approximately 250 a year, down from 2,000. This is widely attributed to changes in behaviour, especially parental behaviour, and to the ‘Back to Sleep’ campaign. But I have never been convinced that ‘risk factors’ such as parental smoking, drug and alcohol intake, or even the widely held view that co-sleeping (bed sharing) are potentially causative factors. I wrote as much in Cot Death: a guilt trip too far 14 years ago.

But now there is real hope that a possible cause has been identified by Daniel Rubens, a paediatric anaesthesiologist at Seattle Children’s Hospital, and founder of the community group the SIDS Research Guild. He is researching the finding of a hearing deficit from inner ear damage, noted at birth in SIDS infants with newborn hearing tests, and its potential relationship to the later mechanism of death. He believes he is close to finding the cause of SIDS.

After 11 years of research, he thinks SIDS could be related to an undetected, inner-ear dysfunction that makes it difficult for a baby to automatically rouse and reposition itself when it is having trouble breathing. This is due to a reduction in oxygen and a build up of carbon dioxide inside the baby’s body. They don’t have the trigger that tells them to move and access fresh air, so they just stop breathing.

Why does this happen? ‘These babies have inner-ear damage, but they can’t tell you,’ says Rubens. ‘They are too young to sit up. The baby has got a problem getting air.’

The research is based on a Rhode Island Department of Health study on infant hearing; in a test group of 31 babies who died from SIDS, all scored lower across three different sound frequencies in the right ear. Babies without the hearing malfunction survived.

Rubens’ research rejects the notion that SIDS is something parents might have contributed to. He suggests that in the event of a fatality, even a highly-trained anaesthesiologist (with all of the monitoring currently available) would struggle to resuscitate a baby with the SIDS predisposition. ‘We need more sophisticated monitoring in order to pick up a potential crisis early; at the very least a different configuration of the currently utilised monitoring to detect the problem early enough to be able to prevent it in a SIDS baby.’

Rubens wants to see more research that would lead to a hearing test to be performed on babies within 48 hours of birth. That screening would detect the unique hearing dysfunction that puts babies at risk for SIDS, and those babies would undergo a more thorough clinical examination within a month.

But there isn't a specific hearing test for SIDS yet. A huge part of Rubens’ research is looking into the possibility of applying the routine newborn hearing screen test to identify it.

One post-mortem of four babies who died from SIDS found that all had bleeding and extensive damage in their inner ear. Rubens then re-created that condition in lab mice. ‘And the animal is at risk of an exact, SIDS-like event,’ he said. ‘The more I look at this, I see it’s correct and we need to see this through. We have a lot of work to do to look into that possibility. This is a major area for which we are seeking funding.’

The SIDS Research Guild has come together to raise $20,000 to help him continue his research. If they are not already supporting this work, I hope the UK’s Lullaby Trust will collaborate. They are, after all, working to achieve the same result.

This was first published here 16.04.2015