Purpose The pathogenesis of febrile status epilepticus is poorly understood, but prior studies suggest an association with temporal lobe abnormalities including hippocampal malrotation. We employ a quantitative morphometric method to assess the association between temporal lobe morphology and febrile status epilepticus. Methods Brain MR imaging was obtained in children presenting with febrile status epilepticus and control subjects as part of the FEBSTAT study. Medial temporal lobe morphologic parameters were measured manually, including distance of the hippocampus from midline, hippocampal height:width ratio, hippocampal angle, collateral sulcus angle, and width of the temporal horn. Results Temporal lobe morphologic parameters are correlated with presence of visual hippocampal malrotation; the strongest association is with left temporal horn width (p < 0.001, Adjusted OR 10.59). Multiple morphologic parameters correlate with febrile status epilepticus, encompassing both right and left sides. This association is statistically strongest in the right temporal lobe, whereas hippocampal malrotation is almost exclusively left-sided in this cohort. The association between temporal lobe measurements and febrile status epilepticus persists when the analysis is restricted to cases with visually normal imaging without hippocampal malrotation or other visually apparent abnormality. Conclusions Several component morphological features of hippocampal malrotation are independently associated with febrile status epilepticus, even when complete hippocampal malrotation is absent. Unexpectedly, this association predominantly involves the right temporal lobe. These findings suggest that a spectrum of bilateral temporal lobe anomalies are associated with febrile status epilepticus in children. Hippocampal malrotation may represent a visually apparent subset of this spectrum.

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