Researchers point to a common cause in sudden death syndromes

March 21, 2019

Sudden Infant Death Syndrome (SIDS) and Sudden Unexpected Death in Epilepsy (SUDEP) are syndromes that share many medical similarities but whose physiological causes are poorly understood. An opinion article publishing March 21 in the journal Trends in Neurosciences suggests that the inability for an individual to wake up when their CO2 blood levels rise, likely due to a faulty neural reflex, may be a shared cause for incidences of death in both disorders.

"If someone's airway is blocked with a blanket, for example, they are unable to expel CO2, which causes their CO2 blood levels to rise. Normally, this triggers a series of reactions that cause the individual to wake up and either re-position themselves so that they can breathe again, or cry out for help, like in the case of a baby," says author Gordon Buchanan, an associate professor of neurology at the University of Iowa. "However, in instances of SIDS and SUDEP, evidence is beginning to suggest that elevated CO2 doesn't trigger this wake-up response like it should, which can ultimately result in death."

Why a person would fail to wake up from increased CO2 is not fully understood, but a potential explanation is that a malfunctioning serotonin receptor in the midbrain may be responsible.

"Serotonin neurons in the medulla are involved in regulation of breathing, and we think the ones in the midbrain are involved in regulating a person's ability to wake up," says Buchanan. "In instances of SIDS and SUDEP, autopsies frequently reveal that there are abnormalities in the individual's serotonin system in the brain.

"It is very possible that there is a direct path by which CO2 is sensed by serotonin receptors in the midbrain, and when there is too much CO2 present, the brain reacts by waking up the individual," he says. "The existence of this direct pathway is important because it could drive future treatments."

However, applying this information to create preventative therapies for these syndromes is still in the works. In addition to validating that SIDS and SUDEP are caused by an inability to wake up because of a defective CO2 system, a safe and reliable way to test if a person has dysfunctional serotonin receptors needs to be developed as well. Currently, such determinations are possible only through autopsies.

In the meantime, parents or caregivers for infants or people with epilepsy should employ the same preventative measures that have been recommended, and largely successful, for decades. "For infants six months and younger, which is the population most susceptible to SIDS, parents should put babies on their backs to sleep. At that age, they can't really roll, so they should stay put through the night," Buchanan says. Further, not putting plush toys or blankets in the crib and dressing the baby in tight-fitting clothing are other guidelines to follow.

"As for people with epilepsy who may be prone to SUDEP, which tends to be people who have nighttime seizures, they can also try to sleep on their backs, although it's less likely that they'll stay like that throughout the night since they can roll," says Buchanan. "And in both cases, using a baby monitor to keep an eye on the individual can be helpful."
-end-
Buchanan is supported by the NIH/NINDS; the Pappajohn Biomedical Institute and Iowa Neuroscience Institute at the University of Iowa; and the Beth Levitt Tross Professorship in Epilepsy Research.

Trends in Neurosciences, Buchanan, G.: "Impaired CO2-induced arousal in SIDS and SUDEP" https://www.cell.com/trends/neurosciences/fulltext/S0166-2236(19)30018-9

Trends in Neurosciences (@TrendsNeuro), published by Cell Press, is a monthly review journal that brings together research covering all disciplines of the neurosciences, allowing researchers, students and teachers to keep up with the last developments, insights, and future directions in the field Visit: http://www.cell.com/trends/neurosciences. To receive Cell Press media alerts, please contact press@cell.com.

Cell Press

Related Epilepsy Articles from Brightsurf:

Focal epilepsy often overlooked
Having subtler symptoms, a form of epilepsy that affects only one part of the brain often goes undiagnosed long enough to cause unexpected seizures that contribute to car crashes, a new study finds.

Antibodies in the brain trigger epilepsy
Certain forms of epilepsy are accompanied by inflammation of important brain regions.

Breaching the brain's defense causes epilepsy
Epileptic seizures can happen to anyone. But how do they occur and what initiates such a rapid response?

Using connectomics to understand epilepsy
Abnormalities in structural brain networks and how brain regions communicate may underlie a variety of disorders, including epilepsy, which is one focus of a two-part Special Issue on the Brain Connectome in Brain Connectivity, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers.

Epilepsy: Triangular relationship in the brain
When an epileptic seizure occurs in the brain, the nerve cells lose their usual pattern and fire in a very fast rhythm.

How concussions may lead to epilepsy
Researchers have identified a cellular response to repeated concussions that may contribute to seizures in mice like those observed following traumatic brain injury in humans.

Understanding epilepsy in pediatric tumors
A KAIST research team led by Professor Jeong Ho Lee of the Graduate School of Medical Science and Engineering has recently identified a neuronal BRAF somatic mutation that causes intrinsic epileptogenicity in pediatric brain tumors.

Can medical marijuana help treat intractable epilepsy?
A new British Journal of Clinical Pharmacology review examines the potential of medicinal cannabis -- or medical marijuana -- for helping patients with intractable epilepsy, in which seizures fail to come under control with standard anticonvulsant treatment.

Fertility rates no different for women with epilepsy
'Myth-busting' study among women with no history of infertility finds that those with epilepsy are just as likely to become pregnant as those without.

Do women with epilepsy have similar likelihood of pregnancy?
Women with epilepsy without a history of infertility or related disorders who wanted to become pregnant were about as likely as their peers without epilepsy to become pregnant.

Read More: Epilepsy News and Epilepsy Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.