青少年肌阵挛癫痫发作过程脑电信号子波熵分析

A wavelet entropy analysis of ictal electroencephalogram signals of juvenile myoclonic epilepsy

摘要:

目的 采用子波熵研究青少年肌阵挛癫痫（JME）发作过程的动态变化，探索其发作的动力学机制，为监测癫痫发作提供更好的指标。方法 采用Gauss连续子波变换对10例JME患者（JME组）癫痫发作的脑电信号进行分解，在此基础上行子波功率谱分析，并计算整体子波熵（En）和分尺度子波熵[En（a）]，根据视觉脑电结果将熵值分为发作间期、发作前期和发作期，观察JME发作全过程子波熵值的动态变化，总结其变化规律并与正常对照组比较。结果 JME组发作期整体子波熵值较发作间期和正常对照组降低（P<0.017），前头部更明显。分尺度子波熵中，11尺度发作期子波熵值较发作间期和正常对照组增高（P<0.017）；9尺度发作期子波熵值低于发作间期和正常对照组（P<0.017）。结论 JME发作时整体子波熵降低，提示全脑活动较发作间期和正常对照变得单一而规律，全脑信息的丰富度和复杂度下降。分尺度子波熵中11尺度发作期子波熵值增高，而9尺度发作期子波熵值降低，提示发作时11尺度脑电活动频率增加，而其他尺度脑电活动频率降低。发作期各导联整体子波熵值下降程度存在差异性，前头部更明显，提示JME放电起源可能与额区皮质相关。

Abstract:

Objective To investigate the changes in electroencephalogram (EEG) signals during seizures of juvenile myoclonic epilepsy (JME) using wavelet entropy and explore the dynamic mechanism of JME, and to provide a better indicator for monitoring seizures.Methods The seizure EEG signals of 10 patients with JME were decomposed with Gaussian continuous wavelet transform. On this basis, we analyzed the wavelet power spectrum and calculated the integral wavelet entropy (En) and individual-scale wavelet entropy [En(a)]. According to the visual EEG analysis, the wavelet entropy was categorized into inter-ictal, pre-ictal and ictal phases. We observed the dynamic changes of wavelet entropy during the entire period of seizure of JME and compared the change pattern with normal controls.Results The integral wavelet entropy in ictal phase was significantly lower than those in inter-ictal phase and normal controls (P<0.017), especially in the frontal region. The 11th scale wavelet entropy of JME in ictal phase was significantly higher than those in inter-ictal phase and normal controls (P<0.017), while the opposite was observed for the 9th scale wavelet entropy (P<0.017).Conclusions The lower integral wavelet entropy in ictal phase of JME suggests simple and regular activity and reduced richness and complexity of the whole brain as compared with inter-ictal phase and normal controls. The increase in the 11th scale wavelet entropy and the decrease in the 9th scale wavelet entropy in ictal phase indicate increased frequency of brain electrical activity in the 11th scale and decreased frequency in other scales. The integral wavelet entropy of different leads in ictal phase decreased to various extents, and the greater decrease in the frontal region suggests the frontal cortex as a source of discharges in JME.