Abstracts

Rationale: BECTS is characterized by few simple partial seizures but high interictal activity. Centrotemporal spikes (CTS) on EEG vary in frequency and lateralization across patients. Previous studies suggest BECTS patients have subtle cognitive deficits and that frequent CTS may disrupt cortical function. We used EEG, functional MRI and cognitive testing to examine 1) language skill in BECTS patients compared to healthy controls and how differences may relate to CTS lateralization 2) what role frequent CTS play in reorganization of language networks.Methods: 13 BECTS patients (age 5-10, 7F, not taking medication) and 12 healthy children (age 5-10, 4F), all right-handed native English speakers, participated. CTS profiles of BECTS patients were determined by epileptologists visually marking 20 minutes of EEG during sleep and 1 hour awake. 2 BECTS patients showed greater left sided CTS activity, 1 had bilateral independent CTS, 2 showed bilateral synchronous CTS, and 8 greater right-sided CTS activity. Participants completed a Story Processing (SP) fMRI task (Schmithorst et al.,2006). This task used a 30-second block design in which short stories were auditorily presented during each active periods. During alternating epochs, broadband noise in the frequency range of speech was presented to control for auditory processing. 5 blocks of noise and 4 blocks of stories were presented. Language skill was assessed using the Clinical Evaluation of Language Fundamentals (CELF, Semel et al., 2003). fMRI data was processed using FMRIB Software Library (FSL). 1 BECTS patient was excluded due to excessive motion. After normalization into MNI space, fixed effects analysis at the individual level and mixed effects analysis at the group level were used to determine group activations. Results: CELF standard scores for BECTS patients (mean 94.6) did not differ significantly from controls (mean 102.8). However, in BECTS patients, a significant negative correlation (r²=.39, p<0.05) was found between CELF scores and the frequency of left CTS averaged over sleep and awake periods. fMRI activation differences were found between groups: controls showed a typical bilateral superior temporal activation pattern for stories>noise (Fig.1). BECTS patients, however, showed no significant group activation due to individual variability. A Region Of Interest (ROI) analysis was performed for the SP task using the left and right temporal areas of significant activation in the group composite. Controls showed a relationship between CELF score and mean activation in the R temporal ROI (r²=.43, p<.05), and a similar trend in in the L ROI (r²=.32, p=.11). No such relationship was found in BECTS patients (p>.3). Conclusions: Results suggest that frequent CTS result in a reorganization of language networks. The relationship between fMRI activation and language scores in controls not present in BECTS patients suggests they may be using alternative networks to support language skill. Subtle language deficits in BECTS may relate to CTS frequency and lateralization, supporting the hypothesis that eliminating CTS may improve cognitive skills.