Abstracts

Rationale: Diffusion tensor imaging (DTI) is increasingly used to evaluate white matter integrity in patients with temporal lobe epilepsy (TLE). Most studies in adult patients had reported decrease of fractional anisotropy (FA) and increase of mean diffusivity (MD) in multiple white matter regions. However reports in children with TLE are scarce and correlation between DTI and electroencephalographic (EEG) findings or clinical variables remains equivocal. We analyzed DTI of children with TLE by using tract-based spatial statics (TBSS) and compared the results with EEG findings and seizure frequency.Methods: We analyzed 13 children with non-lesional mesial TLE (age: from 7 to 19 years, median 16 years) and 19 controls (age: from 7 to 16 years old, median 13 years). TLE patients were diagnosed by seizure manifestations, EEG, brain MRI and FDG-PET. Eight patients had unilateral hippocampal sclerosis. DTI was obtained using 3 tesla MRI scanner with MPG 12 axis. Images from patients with a right temporal focus were flipped so that focus was on the same side (left) for all patients. Comparison of FA images between patients and control was carried out using TBSS implemented in FSL (The Oxford FMRIB Software Library).TBSS project all subjects FA data onto a mean FA tract skeleton, and correction for multiple comparisons was performed. Regions with significant differences (p<0.05) were identified with threshold. Then we calculated mean FA, principal axial diffusivity, radial diffusivity, and mean diffusivity in the skeleton with significant difference on TBSS in each patient. We evaluated correlation between the DTI parameters and number of spikes on inter-ictal EEGs or, frequency of seizures. We used SPSS for static analysis and analyzed by Spearman s correlation test. Results: TBSS showed FA reduction in the left temporal lobe and bilateral frontal lobes and corpus callosum. There were no significant correlation between DTI parameters and number of spikes. Seizure frequency was negatively correlated with FA, and positively with radial diffusivity or mean diffusivity.Conclusions: Children with TLE had FA reduction not only in the epileptogenic temporal lobe but also in widespread white matters. The correlation of DTI abnormality with seizure frequency suggests that repetitive seizure activities may cause white matter injury.