Evaluation of hippocampal infolding angle and incomplete hippocampal inversion in pediatric patients with epilepsy and febrile seizures.

Purpose: We aimed to investigate the frequency of incomplete hippocampal inversion (IHI) and the hippocampal infolding angle (HIA) in pediatric patients with no additional abnormal findings in the brain.

Methods: Pediatric brain magnetic resonance imaging (MRI) examinations conducted between September 2012 and February 2015 were screened and 83 patients with epilepsy, 49 patients with febrile convulsion, and 74 control patients were included in this retrospective study. Presence of IHI was evaluated and HIA was measured on MRI.

Results: IHI was found in 23 patients in the epilepsy group (27.7%), 15 patients in the febrile convulsion group (30.6%), and 14 patients in the control group (19.0%), with no significant difference between the groups (P = 0.27). Compared with the epilepsy and febrile convulsion groups, HIA was significantly larger in the control group in sections of the right cerebral pedincule, the left cerebral pedincule, and the right superior cerebellar pedincule. No correlation was found between the laterality of the epileptogenic focus in the epilepsy group and existence of IHI, nor between age and HIA values among the groups.

Conclusion: Although IHI is not an uncommon abnormality in the normal pediatric population, decreased HIA is more frequently found in patients with epilepsy or febrile convulsions.