In a study designed to better understand sudden unexpected deaths in young children, which usually occur during sleep, researchers have identified brief seizures accompanied by muscle convulsions as a potential cause.

Experts estimate in excess of 3,000 families each year in the United States lose a baby or young child unexpectedly and without explanation. Most are infants, in what is referred to as sudden infant death syndrome, or SIDS, but at least 400 cases involve children age 1 and older, in what is called sudden unexplained death in children (SUDC). Over half of these children are toddlers, between age 1 and 3.

The study findings come from a registry of more than 300 SUDC cases that was set up a decade ago by researchers at NYU Grossman School of Medicine. Researchers used extensive medical record analysis and video evidence donated by families to document the inexplicable deaths of seven toddlers that were potentially attributable to seizures. These seizures lasted less than 60 seconds and occurred within 30 minutes immediately prior to each child’s death, say the study authors.

For decades, researchers have sought an explanation to sudden death events in children, noticing a link between those with a history of febrile seizures (seizures accompanied by fever). Earlier research had reported that children who died suddenly and unexpectedly were 10 times more likely to have had febrile seizures than children who did not die suddenly and unexpectedly. Febrile seizures are also noted in one-third of SUDC cases registered at NYU Langone Health.

Published in the journal Neurology online January 4, the new study involved an analysis by a team of eight physicians of the rare SUDC cases for which there were home video recordings. The recordings, from either security systems or commercial crib cameras, were made while each child was sleeping on the night or afternoon of their death.

Five of the seven recordings were running nonstop at the time and showed direct sound and visible motion indicative of a seizure happening. The remaining two recordings were triggered by sound or motion, but only one suggested that a muscle convulsion, a sign of seizure, had occurred. As well, only one toddler had a documented previous history of febrile seizures. Autopsies, which had been previously performed on all the children in the study, revealed no definitive cause of death.

“Our study, although small, offers the first direct evidence that seizures may be responsible for some sudden deaths in children, which are usually unwitnessed during sleep,” said study lead investigator Laura Gould, MSc, MA, PT, a research assistant professor at NYU Langone. Gould lost her own daughter, Maria, to SUDC at the age of 15 months in 1997, a tragedy that prompted her to successfully lobby to establish the SUDC Registry and Research Collaborative at NYU Langone. Gould points out that if not for the video evidence, the death investigations would not have implicated a seizure.

“These study findings show that seizures are much more common than patients’ medical histories suggest, and that further research is needed to determine if seizures are frequent occurrences in sleep-related deaths in toddlers, and potentially in infants, older children, and adults,” said study senior investigator and neurologist Orrin Devinsky, MD.

Dr. Devinsky, a professor in the Departments of Neurology, Neurosurgery, and Psychiatry, as well as director of NYU Langone’s Comprehensive Epilepsy Center, adds that “convulsive seizures may be the smoking gun that medical science has been looking for to understand why these children die.”

“Studying this phenomenon may also provide critical insight into many other deaths, including those from SIDS and epilepsy,” said Dr. Devinsky, who co-founded the SUDC Registry and Research Collaborative with Gould.

Further research, Dr. Devinsky notes, is also needed to determine precisely how seizures with or without fever may induce sudden death. Previous research in patients with epilepsy, he says, points to difficulty breathing that is known to occur immediately after a seizure and that can lead to death. This has been found to happen more frequently in those who have epilepsy, as it does in the children involved in the study, while they are sleeping face down on the stomach and without anyone witnessing the death.

Continuous monitoring of child deaths and improvements in health records to track how often these convulsive seizures precede death, he explains, will be needed for this to be confirmed. Seizure-related deaths are underreported in people both with and without epilepsy.

For the study, experts in forensic pathology, neurology, and sleep medicine analyzed each recording for video quality, sound, and motion. From this, they were able to determine which toddlers showed signs of muscle convulsions as a sign of seizures prior to their death and when. Access to the videos was and remains strictly limited to the researchers involved in the study.

Funding support for this study was provided by SUDC UK, NYU Langone’s Finding a Cure for Epilepsy and Seizures (FACES), and the SUDC Foundation. Additional funding support was provided by the National Center for Advancing Translational Sciences and National Institutes of Health grant UL1TR001445.

Besides Gould and Dr. Devinsky, other NYU Langone researchers involved in this study are Codi-Ann Reid, BS, and Alcibiades J. Rodriguez, MD. Co-investigators of the SUDC video study group are Alison Krywanczyk, MD, at the Cuyahoga County Medical Examiner’s Office in Cleveland; Kristen Landi, MD, at the New York City Office of the Chief Medical Examiner; Melissa Guzzetta, DO, at the Office of the County Medical Examiner in Middlesex, New Jersey; Heather Jarrell, MD, at the Office of the Medical Investigator, University of New Mexico, in Albuquerque; Kelly Lear, MD, at the Arapahoe County Coroner’s Office in Centennial, Colorado; Tara Mahar, MD, and Katherine Maloney, MD, at the Erie County Medical Examiner’s Office in Buffalo, New York; Declan McGuone, MBBCh, at Yale University in New Haven, Connecticut; Alex Williamson, MD, at Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York; Katheryn Pinneri, MD, at the Montgomery County Forensic Service in Conroe, Texas; and Victoria Delavale, MPH, and Daniel Friedman, MD, at NYU Grossman School of Medicine.

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