Abstracts

Rationale: Benign epilepsy with centrotemporal spikes (BECTS) is a neurodevelopmental disorder with a genetic influence. In spite of its signature electroencephalographic?? pattern and distinct focal motor seizure semiology, little is known regarding the underlying brain anatomical alteration and its corresponding cognitive consequences. In the current study, we hypothesize that anatomical networks in BECTS involve a distributed corticostriatal circuit and the magnitude of abnormal subcortical structures will be related to cognitive performance. Methods: T1 weighted SPGR images (1.5 Telsa GE Signa scanner) were obtained in 13 children with new and recent onset BECTS (age = 10.2 1.4) and 54 controls (age = 13.2 3.0). Automated segmentation and shape analysis of the subcortical structures (caudate, putamen, pallidum and thalamus) were performed using FIRST (part of FSL, http://www.fmrib.ox.ac.uk/fsl)), which is a model-based segmentation tool that searches through linear combinations of shape modes of variation for the most likely shape, based on T1 image intensity. Analysis of variance was performed, with age and head circumference as covariates, to compare subcortical volumes between BECTS and control groups. Specific subcortical volumes in BECTS that were significantly different from controls were correlated with performances in executive function. To assess whether BECTS children with larger putamen volumes performed markedly better than controls, we dichotomized the BECTS group based on total putamen volumes (median split, n=6, > 50th percentile; n=7, < or = 50th percentile) and compared their executive function scores to controls.Results: 1) Among the subcortical regions in corticostriatal network, the putamen is selectively hypertrophied in BECTS, compared to controls (8.4% average increase, p=0.001,effect size d=1.01). 2) In addition to overall volume expansion, shape deformities were present in BECTS, with vertical expansion in the left caudate and bilateral putamen (Figure 1). 3) Larger putamen volumes were significantly linked to better performances on D-KEF card sorting test (left: Spearman s r=0.66, p=0.01; right: r=0.63, p=0.02, Figure 2). 4) BECTS children with larger putamen on average performed better than controls on D-KEF card sorting test (p=0.022, t-test), while those with smaller putamen performed worse than controls (p=0.001, t-test).Conclusions: Children with BECTS showed aberrant volume and shape in subcortical regions that are critical for both motor processing and executive function. Importantly, the hypertrophy appears to be cognitively adaptive, as enlargement was associated with improved cognitive performances. The striatal hypertrophy and shape deformity found in BECTS are discordant with the known normal developmental trajectory of these brain structures. Furthermore, the anatomical abnormalities are evident in a group of children with new and recent onset epilepsy, suggesting that the structural brain anomalies occurred prior to the diagnosis of epilepsy