Febrile Seizures Identified as Potential Cause of Sudden Unexplained Deaths of Children

A study published in the Feb. 13, 2024 journal Neurology designed to investigate the cause of sudden unexplained death of children, which usually occurs during sleep, found that the deaths of seven toddlers examined in the study were related to convulsions, also known as seizures. This finding suggests that many unexplained sleep-related deaths unexpectedly occurring in infants under age one (sudden infant death or SIDS) and in children over age one (sudden unexplained death in childhood or SUDC) may result from seizures.¹

The U.S. Centers for Disease Control and Prevention (CDC) reports that there are approximately 3,400 cases of SIDS in infants under one year old every year in the United States with no obvious cause. In 2020, there were 1,389 deaths due to SIDS, 1,062 deaths due to unknown causes, and 905 deaths due to accidental suffocation and strangulation in bed.²

For many decades, researchers have attempted to find an explanation of why SIDS occurs in children and observed that there is a link between SIDS and children with a history of febrile seizures (seizures accompanied by fever). Research in the past suggested 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.^{3 4}

According to The Sleep Foundation, febrile seizures are relatively common and 1 in 25 children experience at least one febrile seizure triggered by fever.⁵

Study Analyzes Home Video Recordings of Child’s Last Sleep Before Death

In the study published in Neurology, the findings were derived from a registry of over 300 SUDC cases that was set up ten years ago by researchers at New York University Grossman School of Medicine. Medical records and video evidence of seven toddlers aged 13 to 27 molnths, who suddenly died in their sleep, were donated by families to the researchers and were analyzed. A team of eight physicians analyzed the home video recordings. The recordings were either time stamped from security systems or commercial crib cameras, while each child was sleeping right before of their death. Six forensic pathologists, a pediatric epileptologist, and a sleep medicine/epileptologist physician reviewed the videos independently.⁶

Three cases had no significant medical history. Four had common pediatric conditions such preterm birth with recent otitis media (ear infection), chronic otitis media and bilateral myringotomies (surgery to treat chronic ear infections), egg allergy, and febrile seizures. All children had normal development milestones.⁷

Five of the seven video recordings were continuously running at the time and showed sound and visible motion that indicated an occurrence of a seizure. The remaining two recordings were triggered by sound or motion, but only one suggested that a muscle convulsion (a sign of seizure) had occurred and also only one toddler had a documented previous history of febrile seizures.

The autopsies that were performed revealed no definitive cause of death,  however it is well known that pathological evidence of seizures prior to death is difficult to detect in autopsies.⁸

Laura Gould, MSc, lead researcher of the study, said:

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.⁹

Orrin Devinsky, MD, a neurologist and a researcher on the study, added:

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.¹⁰

Risk of Febrile Seizures Higher When Childhood Vaccines are Given Simultaneously

A 2016 study published in Pediatrics quantified how often children may experience febrile seizures after receiving the trivalent flu vaccine when it is given at the same time with either pneumococcal conjugate vaccines (PCV) or a diphtheria-tetanus-pertussis (DTaP) vaccine. Using the Vaccine Safety Datalink, researchers studied children aged six to 23 months who had a febrile seizure within zero to one days of at least one of the three vaccines between 2006 and 2011, which included five flu seasons. In total, there were 333 febrile seizures confirmed following nearly two million vaccinations. The risk of febrile seizures was the highest when all three vaccines were given simultaneously.¹¹
Several other studies have linked febrile seizure risk to other vaccines recommended for children such as the combination DTaP, inactivated poliovirus (IAV) and Haemophilus influenza type B (DTaP-IPV-Hib) and measles-mumps-rubella-varicella (MMRV).¹²

The CDC’s website states:

Febrile seizures can be frightening, but nearly all children who have a febrile seizure recover quickly. Febrile seizure do not cause any permanent harm and do not have any lasting effects.¹³

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