Abstracts

Rationale: We hypothesized there was impaired white matter (WM) and gray matter (GM) integrity in children with frontal lobe epilepsy (FLE), with more extensive WM abnormality than GM abnormality. The aim of this study was to assess WM integrity using DTI and GM integrity using cortical thickness in children with FLE. Methods: 43 patients with FLE, mean age 13.2 years, were recruited. All patients had normal MRI. 28 patients had left FLE and 15 had right FLE. The control group consisted of 44 age-matched healthy subjects, mean age of 12.9 years, without neurological or psychiatric disorders and had normal MRI. DTI and volumetric T1-weighted imaging were acquired on 3T in both patients and controls. DTI was analyzed using FreeSurfer, corrected for multiple comparisons. Cortical thickness was also analyzed using Freesurfer, corrected for multiple comparisons using false discovery rate (FDR). Results: (i) DTI (a) Left FLE: There was significant reduction in fractional anisotropy (FA) in corpus callosum, right precentral and insular WM, and significant increase in apparent diffusion coefficient (ADC) in brainstem. There was a significant increase in axial diffusivity (AD) in brainstem, and decrease in AD in corpus callosum and right angular WM. Significant increases in radial diffusivity (RD) were identified in corpus callosum, left internal capsule, left postcentral WM, brainstem, and right supramarginal, insular and precentral WM after correction for multiple comparisons. (b) Right FLE: There was significant reduction in FA in corpus callosum, right posterior cingulate and angular WM, right thalamus, right and left internal capsule, left supramarginal WM, left external capsule, and brainstem. There was significant elevation in ADC in corpus callosum; right isthmus cingulate, postcentral WM and thalamus, right and left supramarginal WM, left parahippocampal WM, brainstem, and cerebellum. There was significant decrease in AD in right angular and precuneus WM and right internal capsule, and increase in AD in right posterior cingulate, right thalamus, brainstem, and cerebellum. Significant increases in RD were identified in corpus callosum, right temporal stem, right pre and post central and angular WM and right optic radiation; right and left internal capsule, anterior cingulate, superior parietal, and parahippocampal WM; left superior frontal and supramarginal WM, left external capsule, left thalamus, brainstem, and cerebellum after correction for multiple comparisons. (ii) Cortical Thickness (a) Left FLE: There was significant reduction in cortical thickness in the left superior frontal and precentral cortex, right superior frontal, precentral, and inferior temporal cortex (FDR corrected). (ii) Right FLE: There was significant reduction in cortical thickness in the right middle frontal and left lateral occipital cortex (FDR corrected). Conclusions: We have found widespread areas of impaired WM and GM integrity, with more regions of abnormal WM than GM in children with FLE. RD and AD were more sensitive markers of impaired WM integrity than FA and ADC in children with FLE.