Long-term intelligence and memory outcomes of children post convulsive status epilepticus (CSE) have not been systematically investigated despite evidence of short-term impairments in CSE. The present study aimed to describe intelligence and memory outcomes in children within 10 years of CSE and identify potential risk factors for adverse outcomes. In this cohort study, children originally identified by the population-based North London Convulsive Status Epilepticus in Childhood Surveillance Study (NLSTEPSS) were prospectively recruited between July 2009 and February 2013 and invited for neuropsychological assessments and magnetic resonance imaging (MRI) scans. Full-scale intelligence quotients (FSIQs) were measured using the Wechsler Abbreviated Scales of Intelligence (WASI), and global memory scores (GMS) was assessed using the Children’s Memory Scale (CMS). The cohort was analyzed as a whole and stratified into a prolonged febrile seizures (PFS) and non-PFS group. Their performance was compared with population norms and controls. Regression models were fitted to identify predictors of outcomes. With a mean of 8.9 years post-CSE, 28.5% of eligible participants were unable to undertake testing because of their severe neurodevelopmental deficits.
Results: Children with convulsive status epilepticus who undertook formal testing (N = 94) were shown to have significantly lower full-scale intelligence quotients (p = 0.001) and global memory scores (p = 0.025) from controls; the prolonged febrile seizures group (N = 34) had lower full-scale intelligence quotients (p = 0.022) but similar memory quotients (p = 0.88) with controls.
Intracranial volume (ICV), developmental delay at baseline, and active epilepsy at follow-up were predictive of long-term outcomes in the non-prolonged febrile seizures group. The relationship between ICV and outcomes was absent in the prolonged febrile seizures group despite its presence in the control and non-prolonged febrile seizures groups. Post-convulsive status epilepticus, survivors reveal significant intelligence and memory impairments, but prognosis differs by convulsive status epilepticus type; memory scores are uncompromised in the prolonged febrile seizures group despite evidence of their lower full-scale intelligence quotients whereas both are compromised in the non-prolonged febrile seizures group. Correlations between brain volumes and outcomes differ in the prolonged febrile seizures, non-prolonged febrile seizures, and control groups and require further investigation.