DIAGNOSTIC-VALUE OF EEG-ANALYSIS OF EPILEPTIC FOCUS IN MESIAL TEMPORAL-LOBE EPILEPSY (MTLE)

For precise identification of an epileptic focus in mesial temporal lo be epilepsy (MTLE), various techniques, inducing neuroimaging, are emp loyed. We performed topographic and spike dipole analyses to investiga te the correlation between surface electroencephalogram (EEG) and the location of the lesion in 10 patients with MTLE. Six patients with int erictal epileptic spikes on EEG were analyzed by the dipole localizati on method using CDT 1000 (Central Electronics Company, Tokyo). The loc ation of the spike dipoles were com pared with the location of abnorma l lesions revealed by magnetic resonance imaging (MRI). In all 10 case s, EEG topography was also performed to determine an abnormal lesion f rom the EEG background activity. Ln six cases, spike dipoles were loca ted at the mesial temporal lobe, which corresponded to the MRI lesion. Ln seven of the 10 cases, EEG topography revealed the deviation of th e delta band to one side in the frontal to anterior temporal area. Ln these seven cases, the laterality of the delta band deviation coincide d with the site of the MRI abnormality. In one case, a topographic abn ormality was provoked after sleep deprivation. We conclude that EEG an alysis combined with MRI is useful for the evaluation of the epileptic focus in MTLE. Topographic analysis of basic EEG was considered to be beneficial especially in MTLE, in which epileptic spikes were rare.