Intelligence and memory outcomes within 10 years of childhood convulsive status epilepticus

Marina M Martinos,Suresh Pujar,Helen O'Reilly,Michelle De Haan,Brian G.R Neville,Rod C Scott,Richard F.M Chin

doi:10.1016/j.yebeh.2019.03.039

Abstract

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. Children with CSE who undertook formal testing (N = 94) were shown to have significantly lower FSIQ (p = 0.001) and GMS (p = 0.025) from controls; the PFS group (N = 34) had lower FSIQs (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-PFS group. The relationship between ICV and outcomes was absent in the PFS group despite its presence in the control and non-PFS groups. Post-CSE, survivors reveal significant intelligence and memory impairments, but prognosis differs by CSE type; memory scores are uncompromised in the PFS group despite evidence of their lower FSIQ whereas both are compromised in the non-PFS group. Correlations between brain volumes and outcomes differ in the PFS, non-PFS, and control groups and require further investigation.

Highlights

Convulsive status epilepticus (CSE) is the most common neurological emergency in childhood [1] and is associated with a greater risk of pediatric mortality [2], structural brain abnormalities [3,4,5,6,7,8,9,10,11,12,13,14], and an overall poorer quality of life [15]
The inception cohort consisted of children identified and studied in the first-ever population-based study focused on the epidemiology of childhood convulsive status epilepticus (CSE), i.e., the North London Convulsive Status Epilepticus in Childhood Surveillance Study (NLSTEPSS) [21]
Children with non-prolonged febrile seizures (PFS) classified as having any type of seizures prior to CSE baseline were less likely to participate in our neuropsychological assessments (χ2 (1) = 12.4, p = 0.002)

Summary

Introduction

Convulsive status epilepticus (CSE) is the most common neurological emergency in childhood [1] and is associated with a greater risk of pediatric mortality [2], structural brain abnormalities [3,4,5,6,7,8,9,10,11,12,13,14], and an overall poorer quality of life [15]. Long-term outcomes after CSE in childhood are unclear; most studies that have been conducted to investigate this issue are either hospital-based, conducted retrospectively, and/or have involved both adults and children [16,17,18]. One prospective population-based study has focused on long-term outcomes of CSE in childhood, which, utilizes broad measures and does not investigate memory outcomes [19]. The inception cohort consisted of children identified and studied in the first-ever population-based study focused on the epidemiology of childhood CSE, i.e., the North London Convulsive Status Epilepticus in Childhood Surveillance Study (NLSTEPSS) [21]

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Conclusion