In nearly all epileptic children who experienced their first seizure immediately after vaccination, an underlying cause for the epilepsy unrelated to the vaccine can be identified or else the epilepsy is benign, according to a new study.
Previous research had shown that vaccination could induce the first seizures in children who were already genetically predisposed to go on to develop Dravet syndrome, previously called severe myoclonic epilepsy of infancy. This study revealed similar findings for other epilepsies involving a first seizure after vaccination.
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Sixty-five percent of children have identifiable genetic causes for epileptic seizures after vaccination.
“These underlying causes were not limited to SCN1A-related Dravet syndrome but extended to other genetically determined fever-sensitive epilepsies,” Nienke E. Verbeek of University Medical Centre Utrecht in the Netherlands, and her associates reported online. “These results imply that early genetic testing should be considered in all children with vaccination-related onset of epilepsy and might help to support public faith in vaccination programs,” they wrote (Pediatrics 2014 Sept. 15 [doi:10.1542/peds.2014-0690]).
Researchers reviewed the medical data of 990 children in the Netherlands who experienced a seizure after vaccination in their first 2 years of life between 1997 and 2006. Seizures were considered related to vaccination if they occurred within 24 hours of an inactivated vaccine or within 5-12 days of a live vaccine.
Of these children, 26 were later diagnosed with epilepsy and had their first seizure after vaccination. The researchers followed up with 23 of these children when they were an average 10 years old and found them to fall within one of three groups.
The first group included three children (13%) who had already shown developmental delay before their first seizure and were therefore presumed to have preexisting encephalopathy. The second group of 12 children (52%) had epileptic encephalopathy, with an underlying cause found for 10 of them (including 8 with Dravet syndrome).
The third group of eight children (23%) had benign epilepsy, and researchers identified a likely genetic cause in three of these children. Seven children in the third group no longer had seizures, even without taking antiepileptic drugs, “showing that vaccination-related epilepsy onset does not necessarily have a poor prognosis,” the researchers wrote.
The study was supported by the Friends of the UMC Utrecht Foundation on behalf of the Janivo Foundation and the Nuts-Ohra Fund. The authors reported no disclosures.