Abstracts

Rationale: Convulsive status epilepticus (CSE) is the most common neurological emergency and is thought to be associated with unfavourable developmental outcomes. This is especially true of children with a pre-existing neurological condition. Nevertheless, retrospective studies have highlighted an association between hippocampal sclerosis and a childhood history of prolonged febrile seizures (PFS), a type of CSE that occurs in neurologically normal children. Given the well established role of the hippocampus in memory, we would therefore hypothesize that memory impairments may be also present in children with a history of PFS. Methods: We are recruiting children with a history of CSE originally identified by the population-based North London Convulsive Status Epilepticus in childhood surveillance study (NLSTEPSS). Upon recruitment children undergo detailed investigations to determine their longer-term outcome 6-10 years following their episode. Memory abilities are assessed using the Children s Memory Scale (CMS), providing a general memory quotient (GM) along with indices of verbal and visual memory. Full scale IQ (FSIQ) is assessed using the Wechsler Abbreviated Scale of Intelligence (WASI). Results: From the 21 patients assessed using the WASI, 17 (mean age: 8.7 years) were able to complete memory investigations a mean of 7.3 years following their episode. Four non-febrile cases were unable to complete memory investigations due to very low functioning on the WASI (FSIQ range: 50-55). Children classified as non-febrile CSE cases (n=7) were shown to have a GM quotient within the normal range (mean: 97. 14; range: 50-134), which was strongly correlated with their FSIQ (r=0.919, p=0.003). Two out of the 7 non-febrile cases were found to be grossly impaired on the CMS assessment (mean=50).Children following PFS (N=10) were also shown to have a GM quotient within the normal range (mean: 101; range: 78-128), which was positively correlated with their FSIQ (r=0.685, p=0.029). Nevertheless, 4 out of 10 PFS patients were shown to perform within the borderline range in their delayed memory for visual material (mean: 76.5) but not for verbal material (mean: 106). The opposite pattern was observed in a 5th child. This finding points to a possibility of memory impairments in this group of children. Conclusions: The present results show that memory abilities in children with a history of CSE are tightly linked to the child s overall functioning. This becomes particularly evident for the non-febrile cases where more variability in performance exists. These findings also raise the possibility of memory impairments within the PFS group, which is particularly important given retrospective links between hippocampal sclerosis and PFS in the literature.