fMRI shows atypical language lateralization in pediatric epilepsy patients

Purpose: The goal of this study was to compare language lateralization between pediatric epilepsy patients and healthy children. Methods: Two groups of subjects were evaluated with functional magnetic resonance imaging (fMRI) by using a silent verb-generation task. The first group included 18 pediatric epilepsy patients, whereas the control group consisted of 18 age/gender/handedness-matched healthy subjects. Results: A significant difference in hemispheric lateralization index (LI) was found between children with epilepsy (mean LI =-0.038) and the age/gender/handedness-matched healthy control subjects (mean LI = 0.257; t = 6.490, p < 0.0001). A dramatic difference also was observed in the percentage of children with epilepsy (77.78%) who had atypical LI (right-hemispheric or bilateral, LI < 0.1) when compared with the age/gender/handedness-matched group (11.11%; chi(2)= 16.02, p < 0.001). A linear regression analysis showed a trend toward increasing language lateralization with age in healthy controls (R-2= 0.152; p = 0.108). This association was not observed in pediatric epilepsy subjects (R-2= 0.004, p = 0.80). A significant association between language LI and epilepsy duration also was found (R-2= 0.234, p < 0.05). Conclusions: This study shows that epilepsy during childhood is associated with neuroplasticity and reorganization of language function.