Reading comprehension in pediatric focal epilepsy

Research shows that children with epilepsy experience cognitive deficits that are often correlated with seizure type and localization/lateralization of seizure focus. Additionally, research into academic achievement of children with epilepsy indicates that learning disabilities are the norm in this population, with many children experiencing academic deficits above and beyond that accounted for by impaired cognition. Although reading comprehension is a particular area of weakness for children with epilepsy, little is known regarding differential impact of focal seizure activity within reading-specific neural networks and contribution of well-known reading support processes, namely working memory and executive functioning. The purpose of this study was to determine whether focus location (frontal vs. temporal; right vs. left-hemisphere) predicts reading comprehension performance when controlling for decoding. Additionally, this study sought to investigate the contribution of working memory and aspects of executive functioning (EF) to reading comprehension in the presence of intact decoding, and whether the contribution was moderated by age. Information regarding demographic and seizure variables as well as performance on measures of cognition, achievement, and executive function was abstracted from neuropsychological evaluation reports contained in the medical records of 93 children and adolescents (ages 8 to 18) diagnosed with focal epilepsy. Analysis of covariance was conducted on two samples, each containing two focal epilepsy groups: Frontal Lobe Epilepsy/Temporal Lobe Epilepsy (FLE/TLE) and right-/left-lateralized seizure foci. Hierarchical linear regression analyses examined the relationship between reading comprehension, language variables, and executive function variables, specifically in the domains of attention shifting and working memory. Location of seizure focus did not significantly predict differences in reading comprehension whether localized to anterior or posterior brain regions. Similarly, no group differences were found between right- and left-lateralized foci. In the full sample, vocabulary emerged as the best predictor for reading comprehension outcome when controlling for age at seizure onset and decoding ability. Working memory contributed a small amount of variance, however its relationship with reading comprehension was found to be mediated by lower-level reading processes of decoding and vocabulary. No interaction between age and EF resources recruited was found. As a whole, these results are aligned with conceptualization of epilepsy as a network disorder, suggesting that children with focal epilepsy are more broadly impaired due to disruption of brain networks that span interconnected cortical areas that are traditionally thought to have discreet functional correspondence. This finding lends support to the movement toward more white-matter based research regarding functional outcomes, classification of dysfunction, and treatment recommendations.