A Study On The Hypersynchronous Discharge Mechanisms Of Epilepsy By Analyzing EEG Phases Correlation Synchronization

Objective To study the bilateral temporal EEG phases of the temporal lobe epilepsypatients to support that the hypersynchronous discharge is one of the causes ofseizure.Methods Twenty-five human subjects participated the study. Temporal lobeepilepsy (TLE) group (17 subjects) are TLE patients (mean=30.11 years, SD=13.31)with left epileptogenic focus. The control group (8 subjects) are healthy volunteers(mean=31.80 years, SD=10.12). Bilateral temporal EEGs were recorded with MR-95Recorder (Oxford Company). The data were recorded using a precision of 13-bit andsampling rate of 256Hz. Four Ag/Agcl electrodes were placed bilaterally on thesubject's temporal areas, the distance of any adjacent electrodes was 20mm. Extract30see EEGs with no significant noise, each side of the subject is consisted of 7680samples. The phases of these EEGs were extracted with Hilbert transform. Comparedcross-correlation coefficients of (1) left temporal area (epileptic focus) of TLE groupand control group; (2) left and right temporal area in the TLE group. (3) righttemporal area (non-focus of epilepsy) of TLE group and control group, respectively.Statistical analysis was carried out with SPSS 10.0.Results (1) The mean cross correlation coefficients between adjacent recordingelectrodes: are as follows:①in the TLE group, the mean cross correlation coefficientis between 0.801±0.056 and 0.853±0.079 in the left temporal area (epileptic focus)and between 0.581±0.044 and 0.598±0.071 in the right temporal area (non-focus).②in the control group, the mean cross correlation coefficient is between 0.399±0.096 and 0.519±0.057 in bilateral temporal area. (2) The statistical analysis of themean cross correlation coefficients between adjacent recording electrodes: shows:①there is significant difference in the left temporal area between the TLE group and thecontrol group(p＜0.01).②present difference in the right temporal area between the TLE group and the control group(p＜0.05).③present significant differencebetween left temporal area (epileptic focus) and right (non-focus) in the TLEgroup(p＜0.01).④there is no significant difference between left and right temporalarea in the control group. (3) The mean cross correlation coefficients of each subjectin bilateral temporal area of the TLE group are significantly higher than that of thecontrol group's.Conclusion Our study showed that: (1) the cross correlation coefficients of EEGphases of the TLE group was dramatically higher than that of HC group's, especiallyin the left temporal (epileptic focus), which support the occurrence ofhypersynchronous discharge in the epileptic focus. (2) the cross correlationcoefficients of EEG phases of the non-focus in the TLE group were higher than that ofthe control group's but lower than that of the epileptic focus', which indicate thatthere are inferior hypersynchronous discharge in the non-focus.