Abstracts

Rationale: Language is a unique human ability that represents an extension of the development of multiple sensory channels. Identification of the brain regions mediating language has always been the most urgently sought after due to its practical applications: advanced knowledge of the language-specific zones can facilitate surgical planning and reduce the morbidity associated with resection of eloquent cortex, especially in cases of epilepsy surgery. In the present study the Event-related fields (ERF) in EEG was used to examine brain activation profiles associated with receptive language in patients with drug resistant temporal lobe epilepsy (TLE). Methods: Event related fields (ERFs) time-locked to abstract word stimuli (visually presented) were recorded in the context of a continuous word recognition task in 10 patients with TLE. The anatomical location of source activities was determined by co-registering EEG coordinates onto the patients’ structural MRI scans. Results: The majority of patients (7/10) showed atypical lateralization of language (bilateral or right hemispheric). The incidence of atypical lateralization of language-specific activity was higher among patients with left TLE compared with right (5 vs.2). Four patients underwent in addition Wada-testing. The results of Wada-test correlated well in 3 of 4 patients with results of EFRs in EEG. Conclusions: EFRs in EEG can contribute to the lateralization of receptive language area and is an important non-invasive tool for presurgical planning.