Spectrum, Evolution, and Clinical Relationship of Magnetic Resonance Imaging in 31 Children with Febrile Infection-Related Epilepsy Syndrome.

OBJECTIVE:  Describing spectrum, evolution, and clinical relationship of brain magnetic resonance imaging (MRI) findings in a large case series of children with febrile infection-related epilepsy syndrome (FIRES).

METHODS:  This retrospective study included 31 children with FIRES. Clinical data and MRI findings of the brain were evaluated. Poor clinical outcome was defined as severe disability, persistent vegetative state or stupor, very low intelligence quotient (<80), or death (modified Rankin scale 4-6 and Glasgow Outcome Score 1-3).

RESULTS:  Seventeen (54.8%) children with FIRES showed no abnormalities in the initial MRI, whereas 28 (90.3%) children showed MRI abnormalities at follow-up. The most frequent abnormalities were brain atrophy (74.2%) and T2/fluid-attenuated inversion recovery changes (64.5%), mostly hippocampal (45.2%). Generalized brain atrophy was the most frequent type of atrophy (58%). The earliest atrophy was recorded 9 days after the onset of disease. It progressed even beyond the acute phase in most children (51.6%). The exploratory data analysis revealed nominal significance between all MRI abnormalities considered together and poor outcome ( p  = 0.049) and between generalized brain atrophy and anesthesia ( p  = 0.024). After adjustment for multiple testing, the p- values were not significant. The outcome in four (12.9%) children was not poor despite generalized brain atrophy.

CONCLUSION:  In contrast to the uniform clinical course, MRI demonstrated a broad spectrum of findings. Initially, these were mostly normal and therefore indicative of FIRES but then changed rapidly and were mostly progressive despite the stable chronic course. The cause may be ongoing disease, treatment intensity, or both. Future studies should focus on what process underlies the onset and the progression of brain atrophy. However, brain atrophy was not always related to poor outcomes in children despite FIRES.