Saturday, March 30, 2019

Impaired CO(2)-Induced arousal in SIDS and SUDEP

Buchanan GF. Impaired CO(2)-Induced Arousal in SIDS and SUDEP. Trends Neurosci. 2019 Mar 8. pii: S0166-2236(19)30018-9. doi:10.1016/j.tins.2019.02.002. [Epub ahead of print]

Premature, sudden death is devastating. Certain patient populations are at greater risk to succumb to sudden death. For instance, infants under 1year of age are at risk for sudden infant death syndrome (SIDS), and patients with epilepsy are at risk for sudden unexpected death in epilepsy (SUDEP). Deaths are attributed to these syndromic entities in these select populations when other diagnoses have been excluded. There are a number of similarities between these syndromes, and the commonalities suggest that the two syndromes may share certain etiological features. One such feature may be deficiency of arousal to CO2. Under normal conditions, CO2 is a potent arousal stimulus. Circumstances surrounding SIDS and SUDEP deaths often facilitate CO2 elevation, and faulty CO2 arousal mechanisms could, at least in part, contribute to death.

Every parent’s worst fear is not being able to keep their child safe. And a mysterious condition known as sudden infant death syndrome (SIDS) is enough to keep any new parent awake at night.

What’s so troubling about SIDS is that no one really understands why a seemingly healthy baby goes to sleep and never wakes up. But a new opinion review paper suggests that SIDS and other forms of sudden death syndromes — which impact people of all ages and seem to strike without warning or cause — may share a common, neurological cause.

Some individuals may be prone to sudden death syndromes because they are born with a neurological difference that can be fatal under the right circumstances, explains Gordon Buchanan, a neurologist and epileptologist at the University of Iowa who authored the opinion review paper in Trends in Neurosciences. Among these people, there seems to be a problem with the part of the brain that controls breathing and waking during sleep…

Buchanan thinks that individuals who succumb to sudden death syndromes may have malfunctioning serotonin receptors in their brains. These receptors are part of our brain’s “suffocation alarm system” and help to ensure that blood oxygen and carbon dioxide (CO2) levels are healthy. But Buchanan thinks that a rare neurological difference causes some people’s brains to be bad at detecting when blood CO2 levels get too high — which is a signal to our bodies that we could be suffocating. Instead of waking up like most people would, those with this defect stay asleep and are seemingly powerless against what’s happening to them…

“The possibility that SIDS and SUDEP lie on a sudden death continuum of sorts has been known in the SUDEP community for some time … using known mechanisms for SIDS as a starting point for understanding SUDEP seemed like a good place to start,” he said. “Defects in the brain stem serotonin system have been identified in the brains of several cohorts of babies that have dies of SIDS. Similar anatomical defects are starting to be identified in pathological and imaging studies of people who have died of SUDEP.”…

Researchers have made some recent progress in understanding what causes complex syndromes like SIDS. Last year, a team of researchers found a genetic mutation affecting respiratory muscle function was associated with a subset of SIDS cases. Another recent study found that smoking just one cigarette per day during pregnancy can double a baby’s risk of SIDS. But more research is needed to paint a more precise picture of what’s behind these bewildering cases and how to test for them.

For now, Buchanan recommends that at-risk populations, like people with epilepsy and parents of infants, follow preventive measures against sudden death. Parents should place the babies on their backs to sleep and take care to reduce plush toys, pillows, blankets, and loose-fitting clothing in the crib. People with epilepsy can also take precautions, such as ensuring their condition is properly managed, sleeping on their back, and using a seizure alarm or monitor to alert family or neighbors if they have a seizure at night.

Courtesy of Doximity

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