Katariina Mankinen1, Pieta Ipatti2, Marika Harila3, Juha Nikkinen2, Jyri-Johan Paakki2, Seppo Rytky4, Tuomo Starck2, Jukka Remes2, Maksym Tokariev5, Synnöve Carlson5, Osmo Tervonen2, Heikki Rantala6, Vesa Kiviniemi2. 1. Department of Paediatrics, Oulu University Hospital, PB 29, 90014 Oulu, Finland. Electronic address: katariina.mankinen@oulu.fi. 2. Clinic of Diagnostic Radiology, Oulu University Hospital, Finland. 3. Department of Neurology, Oulu University Hospital, Finland. 4. Department of Clinical Neurophysiology, Oulu University Hospital, Finland. 5. Brain Research Unit, O.V. Lounasmaa Laboratory, Aalto University School of Science, P.B. 15100, 00076 Aalto, Finland; Neuroscience Unit, Institute of Biomedicine/Physiology, University of Helsinki, P.B. 63, 00014 University of Helsinki, Finland. 6. Department of Paediatrics, Oulu University Hospital, PB 29, 90014 Oulu, Finland.
Abstract
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.
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.