| Epilepsy is one of the most common diseases of the nervous system,which is as high as 1/3 of patients were the medically refractory epilepsy,who still have seizures after treatment with antiepileptic drugs.One of the treatment for medically refractory epilepsy is epilepsy surgery,the objective of epilepsy surgery is the complete resection or disconnection of the epileptogenic zone.The key to epilepsy surgery is accurate positioning.Our study is aimed at oscillations for ictal ECo Gs in epilepsy,thus providing the new ideas and techniques for positioning epileptogenic zone.Objective: In this study,ictal multi-channel electrocorticogram datas of patients with medically refractory epilepsy recorded intracranially were taken as the research subjects.We study the temporal and spatial distribution characteristics of power in the ictal multi-channel electrocorticogram(ECo Gs)in low frequency oscillations: ?[0~4Hz),?[4~8Hz),?[8~13Hz),?[13~30Hz),and high frequency oscillations: ? [30~80Hz),R[80~250Hz),FR[250~500Hz] and then research on whether high frequency oscillations are more sensitive and accurate than the low frequency oscillations of positioning of epileptogenic zone.It is expected that this research will provide innovative ideas and techniques for locating epileptogenic zone.Methods: 1.Experimental datas: provided by the Comprehensive Epilepsy Center of Beijing in Xuanwu Hospital of Capital Medical University,they were multi-channel ECo Gs datas from 6 patients with refractory epilepsy undertaking surgical evaluation at between 2012 and 2014,including ictal and interictal ECo Gs datas.2.ECo Gs segment selection: selected five seconds of ECo Gs data for analysis.3.Analysis of ECo Gs:(1)Preprocessing of the ECo Gs: Remove the baseline drift,power frequency interference and artifact in the original ECo Gs.(2)The Fast Fourier Transform(FFT)was applied to calculate energy density of each frequency band: ?[0~4Hz),?[4~8Hz),?[8 ~ 13Hz),?[13 ~ 30Hz),?[30 ~ 80Hz),R[80~250Hz),FR[250~500Hz].(3)We selected 0.5s,including a peak point when the power of each frequency band reached a peak as the feature time period.(4)Then,calculating the topographical maps of each frequency band in the feature time period,comparing the space distribution of energy density of high frequency and low frequency oscillations.4.Statistical analysis: Experimental results comparison were calculated by t test.Results: 1.The dynamic changes of energy density from 6 patients in ictal ECo Gs showed approximately the same trend in high frequency components and low frequency components.The power was increased 2s prior to the clinical seizure onset,shoot up 1s prior to the clinical seizure onset and reached a peak 0.5 s before clinical seizure onset.At 2s after clinical seizure onset,it slipped to its baseline level.2.In addition to No.2 patients and No.4 patients,the power of each frequency band in the feature time period from other patients showed that: compared with the delta,alpha,beta,gamma,ripple,fast ripple,the power of theta bands was the highest,and there were significant differences between the power of theta with others;compared with the low frequency components,power of high frequency components was lower.3.The topographical maps of low frequency components and high frequency components in the feature time period from 6 patients showed that the salient regions of high frequency components were different from the low frequency components.4.The power of each frequency band in ictal period was significantly higher than that in interictal(P<0.05).5.The power of ? band is highest than others in ictal ECo Gs(P<0.05,P<0.01),that is characteristic frequency band.Conclusion: 1.The ictal ECo Gs power increased prior to the clinical epileptic seizures and reached a peak 0.5 s before clinical seizure onset,then the power down.2.The characteristic frequency band of ictal ECo Gs is ? band.3.Spatially,energy significant regions of high frequency oscillations were different from the low frequency oscillations. |
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