Language in childhood epilepsy: A systematic review and meta-analysis.

The abnormal brain activity associated with childhood epilepsy can have an impact on the developmental trajectory of cognitive processes, like language, in this population. However, there is variation in how researchers study language ability in children with epilepsy and the findings that are reported (no differences vs. a significant difference). The current systematic review and meta-analysis uses data from 13 available studies to consider the magnitude of language differences in children with epilepsy compared to their typically developing peers. Seizure classification, age of onset, component of language measured, and instrument used to measure language were all considered as potential moderators of differences in language skill. The results indicate a significant large effect size for language deficits in children with epilepsy compared to their peers. Seizure classification partially, but not fully, accounts for the variability in effect size. In addition, effect sizes differ relative to component of language measured; effect sizes were greatest in magnitude for semantic language and verbal fluency, and minimal for syntax, but only when including all studies of children with epilepsy, regardless of seizure classification. These findings differ when considering language component in children with generalized or focal seizures only. The data reported here also indicate distinct differences in effect size depending on type of instrument used to measure one aspect of language, verbal fluency.