Abstracts

HIMAL a form of hippocampal malrotation with a normal corpus callosum is characterized by incomplete inversion of the hippocampus with a rounded shape and blurred internal architecture (Barsi et al. Neuroradiology 42: 339-345, 2000). It is unclear whether HIMAL is a pathological finding or a normal variant., FEBSTAT is a prospective multicenter study of febrile status epilepticus (FSE) ([ge]30 min) designed to determine whether prolonged febrile seizures cause acute hippocampal damage and if so, does it lead to mesial temporal sclerosis? As part of the study eligible subjects have a baseline MRI within 72 hours of the episode of status and a follow-up MRI at one year. All MRIs have quantitative analysis of hippocampal volume and T2 signal as well as visual analysis by two central neuroradiologists blinded to the clinical details. For controls, we used a cohort of children with a first febrile seizure who had MRIs using a similar protocol., As of May 1, 107 children with FSE have been enrolled. We have finished analyzing the data from 53 subjects and 58 controls. There were a total of 12 cases of HIMAL all of whom were on the left side. Of the FSE cases, HIMAL was present in 9 of 53 (17%), compared with 2 of 23 cases (9%) with complex febrile seizures (FS) lasting [lt]30 min and only 1 (3%) of 35 cases of simple FS. On logistic regression the odds ratio for having HIMAL in cases with FSE compared with simple FS was 7.0 (95%CI 0.8-57.6) and for complex vs simple FS 2.1 (95%CI 0.4-10.8). Of note is that none of the cases of HIMAL had more than mildly increased T2 signal in the left hippocampus. None of the cases with markedly increased T2 signal were in the children with HIMAL., These preliminary data indicate that HIMAL is a developmental malformation that occurs predominantly or exclusively on the left. The higher frequency of HIMAL in children with prolonged FS suggests that it is a pathologic finding. Longer follow-up and subsequent imaging will be needed to ascertain whether there is higher rate of subsequent temporal lobe epilepsy and mesial temporal sclerosis in these children., (Supported by: Funded by grant NS 43209 [ldquo]Consequences of Prolonged Febrile Seizures in Childhood[quot] from NINDS and HD 36867 from NICHD.)