Atypical language lateralisation associated with right fronto-temporal grey matter increases — a combined fMRI and VBM study in left-sided mesial temporal lobe epilepsy patients

By combining language functional magnetic resonance imaging and voxel-based morphometry in patients with left-sided mesial temporal lobe epilepsy and hippocampal sclerosis, we studied whether atypical language dominance is associated with temporal and/or extratemporal cortical changes. Using verbal fluency functional magnetic resonance imaging for language lateralisation, we identified 20 patients with left-sided mesial temporal lobe epilepsy with hippocampal sclerosis and atypical language lateralisation. These patients were compared with a group of 20 matched left-sided mesial temporal lobe epilepsy patients who had typical language lateralisation. Using T1-weighted 3D images of all patients and voxel-based morphometry. we compared grey matter volumes between the groups of patients. We also correlated grey matter volumes with the degree of atypical language activation. Patients with atypical language lateralisation had increases of grey matter volumes, mainly within right-sided temporo-lateral cortex (x =59, y = 16, z = 1,T= 6.36, p