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Background and Aims: The changes in functional brain organization associated with paediatric epilepsy are largely unknown. Since children with epilepsy are at risk of developing learning difficulties even before or shortly after the onset of epilepsy, we assessed the functional organization of memory and language in paediatric patients with temporal lobe epilepsy (TLE) at an early stage in epilepsy., Methods: Functional magnetic resonance imaging was used to measure the blood oxygenation level-dependent (BOLD) response to four cognitive tasks measuring reading, story listening, memory encoding and retrieval in a population-based group of children with TLE of unknown cause (n = 21) and of normal intelligence and a healthy age and gender-matched control group (n = 21)., Results: Significant BOLD response differences were found only in one of the four tasks. In the story listening task, significant differences were found in the right hemispheric temporal structures, thalamus and basal ganglia. Both activation and deactivation differed significantly between the groups, activation being increased and deactivation decreased in the TLE group. Furthermore, the patients with abnormal electroencephalograms (EEGs) showed significantly increased activation bilaterally in the temporal structures, basal ganglia and thalamus relative to those with normal EEGs. The patients with normal interictal EEGs had a significantly stronger deactivation than those with abnormal EEGs or the controls, the differences being located outside the temporal structures., Conclusions: Our results suggest that TLE entails a widespread disruption of brain networks. This needs to be taken into consideration when evaluating learning abilities in patients with TLE. The thalamus seems to play an active role in TLE. The changes in deactivation may reflect neuronal inhibition., (Copyright © 2015 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Functional resting-state connectivity has been shown to be altered in certain adult epilepsy populations, but few connectivity studies have been performed on pediatric epilepsy patients. Here functional connectivity was measured in pediatric, non-lesional temporal lobe epilepsy patients with normal intelligence and compared with that in age and gender-matched healthy controls using the independent component analysis method. We hypothesized that children with non-lesional temporal lobe epilepsy have disrupted functional connectivity within resting-state networks. Significant differences were demonstrated between the two groups, pointing to a decrease in connectivity. When the results were analyzed according to the interictal electroencephalogram findings, however, the connectivity disruptions were seen in different networks. In addition, increased connectivity and abnormally anti-correlated thalamic activity was detected only in the patients with abnormal electroencephalograms. In summary, connectivity disruptions are already to be seen at an early stage of epilepsy, and epileptiform activity seems to affect connectivity differently. The results indicate that interictal epileptiform activity may lead to reorganization of the resting-state brain networks, but further studies would be needed in order to understand the pathophysiology behind this phenomenon., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Recent findings on intracortical EEG measurements show that the synchrony of localized neuronal networks is altered in epileptogenesis, leading to generalized seizure activity via connector hubs in the neuronal networks. Regional homogeneity (ReHo) analysis of blood oxygen level-dependent (BOLD) signals has demonstrated localized signal synchrony and disease-related alterations in a number of instances. We wanted to find out whether the ReHo of resting-state activity can be used to detect regional signal synchrony alterations in children with non-lesional temporal lobe epilepsy (TLE). Twenty-one TLE patients were compared with age and gender-matched healthy controls. Significantly increased ReHo was discovered in the posterior cingulate gyrus and the right medial temporal lobe of the patients, and they also had significantly decreased ReHo in the cerebellum compared with the healthy controls. However, the alterations in ReHo differed between the patients with normal and abnormal interictal EEGs, the latter showing significantly increased ReHo in the right fusiform gyrus and significantly decreased ReHo in the right medial frontal gyrus relative to the controls, while those with normal EEGs had significantly increased ReHo in the right inferior temporal gyrus and the left posterior cingulate gyrus. We conclude that altered BOLD signal synchrony can be detected in the cerebral and cerebellar cortices of children with TLE even in the absence of interictal EEG abnormalities., (Copyright © 2010 Elsevier B.V. All rights reserved.)