Epileptic foci lateralization from interictal scalp EEG by applying causal analysis

Objective To lateralize epileptic foci in interictal electroencephalography (EEG) signal by using causal analysis method.Methods On the basis of frequency domain causal analysis,the adapted directed transfer function (ADTF),power spectrum weighted ADTF(psADTF) method was proposed by applying the power spectrum information in defined frequency band with normalized ADTF,to fit the frequency information features of different epileptic wave.EEG signals of two groups of 30 epilepsy patients were analyzed by psADTF.Group Ⅰ included 15 presurgical patients and 104 epilepsy spikes were picked from EEG signals.Group Ⅱ included 15 outpatient patients and 98 epilepsy spikes were picked from EEG signals.Results 96 of 104 spikes of group Ⅰ were lateralized properly by psADTF according to surgery sites,and the accuracy rate was 92％.94 of 98 spikes of group Ⅱ were lateralized properly by psADTF according to three technicians' judgments,with the accuracy rate of 96％.Conclusion Our results proves that the psADTF method over interictal EEG spikes can be a great help to clinical epileptic foci lateralization. Key words: Epilepsy; Causal analysis; Interictal EEG; Adapted directed transfer function