Children with new-onset epilepsy exhibit diffusion abnormalities in cerebral white matter in the absence of volumetric differences

Abstract

The purpose of this investigation was to examine the diffusion properties of cerebral white matter in children with recent onset epilepsy (n=19) compared to healthy controls (n=11). Subjects underwent DTI with quantification of mean diffusion (MD), fractional anisotropy (FA), axial diffusivity (D(ax)) and radial diffusivity (D(rad)) for regions of interest including anterior and posterior corpus callosum, fornix, cingulum, and internal and external capsules. Quantitative volumetrics were also performed for the corpus callosum and its subregions (anterior, midbody and posterior) and total lobar white and gray matter for the frontal, parietal, temporal and occipital lobes. The results demonstrated no group differences in total lobar gray or white matter volumes or volume of the corpus callosum and its subregions, but did show reduced FA and increased D(rad) in the posterior corpus callosum and cingulum. These results provide the earliest indication of microstructural abnormality in cerebral white matter among children with idiopathic epilepsies. This abnormality occurs in the context of normal volumetrics and suggests disruption in myelination processes.

Figure 1

Three axial slices from a representative FA map show image quality and ROI locations. Color coded ROIs are labeled as follows: cyan anterior corpus callosum, yellow - posterior corpus callosum, red - fornix, magenta - cingulum, green - internal capsule, blue - external capsule.

Figure 2

Mean total white (left panel) and gray (right panel) matter volumes for frontal, parietal, temporal and occipital lobes in children with epilepsy compared to healthy controls. There were no group differences across any of these regions of interest.

Figure 3

Mean volumes for anterior, midbody, posterior and total corpus callosum in children with epilepsy compared to healthy controls. There were no group differences across any of these regions of interest.

Figure 4

Mean DTI values (FA, MD, D_ax and D_rad) of six white matter structures (anterior and posterior corpus callosum, fornix, cingulum, internal capsule and external capsule) for epilepsy and control groups. * indicates p<0.05 for group difference by analysis of covariance and error bars indicate standard error.