E-ISSN 2636-865X
Research Article
Interhemispheric Correlation and Epileptic Seizures: Are They Related? A Preliminary Retrospective Study
1 İzmir Katip Çelebi University Faculty of Medicine, Biophysics, Izmir, Turkey  
2 İzmir Katip Çelebi University Faculty of Medicine, Neurology, İzmir, Turkey  
3 İzmir University Faculty of Medicine, Biophysics, İzmir, Turkey  
Neurol Sci Neurophysiol 2015; 32: 361-371

Key Words: Focal Epilepsy; Electroencephalogram; Seizure prediction; Interhemispheric correlation

Objectives: For the purpose of predicting seizure activities in focal temporal lobe epilepsy we examined interhemispheric correlation coefficients in pre-ictal EEG data.


Materials and Methods: We used video-EEG data obtained from the İzmir Katip Çelebi University Atatürk Training and Research Hospital Neurology Department database to conduct preliminary retrospective analyses. 31 patients (mean age 32.3 ± 7.6; 17 female) diagnosed with focal temporal lobe epilepsy in 2010-2013 were randomly selected and a total of 52 seizures were analyzed. 20 sec pre-ictal EEG data were studied for each seizure. In order to observe the change in the correlation coefficients 20 sec pre-ictal EEG data were divided into 10 windows (each 2 sec). The furthest window to the seizure was labeled as 1stwindow, the closest window to the seizure was labeled as 10th window. Interhemispheric Pearson correlation coefficients were computed for each window in 9 electrode pairs. The variability of the correlation coefficients between windows was analyzed with Repeated Measures of ANOVA.


Results: Pearson correlation coefficients decreased significantly from the 1st window to the 10th window in the following electrode pairs: F7T1-F8T2; T1T3-T2T4; FP1F3- FP2F4; C3P3-C4P4 (p<0.05). Post hoc multiple comparison analysis revealed that the significant difference in correlation coefficients was mainly observed between the first two windows (0-4 seconds) before seizure onset and the last three windows (14-20 seconds) before seizure onset.


Conclusion: The results of the present study suggest that interhemispheric correlation may be applicable for the detection of epileptic seizures in EEG signals.

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