Abstracts

Rationale: Benign Epilepsy with Centrotemporal Spikes (BECTS) and Childhood Absence Epilepsy (CAE) are the most common childhood epilepsy syndromes and they share a similar age characteristics; age of seizure onset is 3 to 12 years (peak 7-8 years for BECTS, 5-6 years for CAE), and seizures typically self-remit by the age of 15-17 years.  However, the two syndromes clearly differ in frequency of seizures (very frequent throughout a day in CAE, but infrequent and usually nocturnal in BECTS); EEG pattern (BECTS exhibits focal centrotemporal interictal spikes and CAE has generalized 3Hz spike and waves during seizures). Subsets of patient in both groups show cognitive or behavioral problems, but with different profiles, i.e., children with BECTS may have more difficulties with language or processing speed, whereas children with CAE may have attention problems. The aim of this study is to investigate whether children of the same age with BECTS, CAE and typically-developing children have significant differences in grey matter (GM) volume that may underlie the different profiles of these syndromes. Methods: Twenty one patients with newly-diagnosed BECTS (age: 5-12 yrs, mean ± SD: 8.8±2.0 yrs, F/M=9/12) and 18 newly diagnosed and drug naïve CAE (6-11 yrs, 8.8±1.8 yrs, 9/9) were included and compared to31 typically-developing control participants (5-13 yrs, 8.3±2.2 yrs, 16/15). T1-weighted MRI images with 1mm isotropic voxel resolution were acquired for all participants at the time of diagnosis for both groups. Voxel-based morphometry was utilized to investigate GM volume differences among BECTS, CAE, and controls. Age, gender and total intracranial volume were included as covariates. A general linear model approach was used to examine differences between groups, and a non-parametric approach used for multiple comparisons correction. We also examined the effect of age on GM volume in all three groups. In addition to the whole brain analysis, we chose regions of interest (ROI) analysis based on previous literature suggesting the involvement of these regions in BECTS or CAE. The group differences of GM volume was tested with 2-sample t-test and one-way ANOVA. Results: In the whole brain group comparisons, the GM volume in CAE was statistically significantly decreased in the areas of right inferior frontal and anterior temporal compared to BECTS and controls (F=27.53, p < .001) (Fig. 1). In the control group, GM volume in bifrontal lobes showed a negative correlation with age, whereas no correlation was found in either CAE or BECTS.  With ROI analyses, the GM volume of posterior thalami was increased in CAE group compared to other 2 groups.  Conclusions: This study shows that there are GM volume differences between CAE and BECTS. The two most common types of childhood epilepsy, BECTS and CAE share some similar features, but semiology of seizures and electrophysiological features are very different. Our findings of grey matter volume differences may suggest that there may be localized cortical maturation differences between these two types of epilepsy.  Funding: NIH/NINDS R01 NS065840