Hippocampal sclerosis and temporal lobe epilepsy following febrile status epilepticus: The FEBSTAT study

Darrell V. Lewis, James Voyvodic, Shlomo Shinnar, Stephen Chan, Jacqueline A. Bello, Solomon L. Moshé, Douglas R. Nordli, L. Matthew Frank, John M. Pellock, Dale C. Hesdorffer, Yuan Xu, Ruth C. Shinnar, Syndi Seinfeld, Leon G. Epstein, David Masur, William Gallentine, Erica Weiss, Xiaoyan Deng, Shumei Sun

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: This study was undertaken to determine whether hippocampal T2 hyperintensity predicts sequelae of febrile status epilepticus, including hippocampal atrophy, sclerosis, and mesial temporal lobe epilepsy. Methods: Acute magnetic resonance imaging (MRI) was obtained within a mean of 4.4 (SD = 5.5, median = 2.0) days after febrile status on >200 infants with follow-up MRI at approximately 1, 5, and 10 years. Hippocampal size, morphology, and T2 signal intensity were scored visually by neuroradiologists blinded to clinical details. Hippocampal volumetry provided quantitative measurement. Upon the occurrence of two or more unprovoked seizures, subjects were reassessed for epilepsy. Hippocampal volumes were normalized using total brain volumes. Results: Fourteen of 22 subjects with acute hippocampal T2 hyperintensity returned for follow-up MRI, and 10 developed definite hippocampal sclerosis, which persisted through the 10-year follow-up. Hippocampi appearing normal initially remained normal on visual inspection. However, in subjects with normal-appearing hippocampi, volumetrics indicated that male, but not female, hippocampi were smaller than controls, but increasing hippocampal asymmetry was not seen following febrile status. Forty-four subjects developed epilepsy; six developed mesial temporal lobe epilepsy and, of the six, two had definite, two had equivocal, and two had no hippocampal sclerosis. Only one subject developed mesial temporal epilepsy without initial hyperintensity, and that subject had hippocampal malrotation. Ten-year cumulative incidence of all types of epilepsy, including mesial temporal epilepsy, was highest in subjects with initial T2 hyperintensity and lowest in those with normal signal and no other brain abnormalities. Significance: Hippocampal T2 hyperintensity following febrile status epilepticus predicted hippocampal sclerosis and significant likelihood of mesial temporal lobe epilepsy. Normal hippocampal appearance in the acute postictal MRI was followed by maintained normal appearance, symmetric growth, and lower risk of epilepsy. Volumetric measurement detected mildly decreased hippocampal volume in males with febrile status.

Original languageEnglish (US)
Pages (from-to)1568-1580
Number of pages13
JournalEpilepsia
Volume65
Issue number6
DOIs
StatePublished - Jun 2024

Keywords

  • MRI volumetry
  • T2 signal intensity
  • febrile seizures
  • hippocampal malrotation

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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