Identifying lateralization of bilateral temporal lobe epilepsy (TLE) is a challenging issue; scalp electroencephalography (EEG) and routine band electrocorticography (ECoG) fail to reveal the epileptogenic focus for further temporal lobectomy treatment. High-frequency oscillations (HFOs) can be utilized as a biomarker for lateralizing the onset zone in suspected bitemporal epilepsy. Except subjective vision detect the HFOs, objective verification should be performed to raise the accuracy. In the present research, we prospectively studied 10 patients with refractory temporal seizures and who underwent ECoG with wide-band frequency amplifiers (2,048 Hz); all patients had a class I outcome after temporal resection. Pre- and ictal HFOs will be analyzed by wavelet transform (WT) and Granger causality (GC) to objectively verify lateralization of the seizure onset zone (SOZ). WT analysis showed ictal HFOs in 10 patients mainly covered from 80 to 115 Hz (average, 92.59 ± 10.23 Hz), and there was distinct bandpass boundary between pre-ictal HFOs and ictal HFOs. GC analysis showed five patients (2, 4, 5, 6, and 7), no matter the pre-ictal or ictal state, had the highest GC degree in SOZ itself. The remaining patients (1, 3, 8, 9, and 10) had the highest GC degree in SOZ with its adjacent regions in the pre-ictal and ictal stages. GC analysis further confirmed the result of the WT and suggested HFOs are initiated and propagated in the local brain region mainly, afterward, transmitting to adjacent brain regions. These results indicated that the combination of WT and GC analyses significantly contributes to accurate lateralization in patients with suspected bitemporal epilepsy.

中文翻译：

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使用小波变换和格兰杰因果分析对疑似双颞叶癫痫患者进行发作性高频振荡

识别双侧颞叶癫痫 (TLE) 的偏侧化是一个具有挑战性的问题；头皮脑电图 (EEG) 和常规带状皮层电图 (ECoG) 未能揭示进一步颞叶切除术治疗的致痫灶。高频振荡 (HFO) 可用作将疑似双颞叶癫痫发作区偏侧化的生物标志物。除了主观视觉检测HFO外，还应进行客观验证以提高准确性。在本研究中，我们前瞻性地研究了 10 名难治性颞叶癫痫患者，他们接受了宽带频率放大器 (2,048 Hz) 的 ECoG；所有患者在颞叶切除术后均达到 I 级结果。将通过小波变换 (WT) 和格兰杰因果关系 (GC) 分析发作前和发作期 HFO，以客观验证癫痫发作区 (SOZ) 的偏侧化。WT 分析显示 10 名患者的发作期 HFOs 主要覆盖 80 至 115 Hz（平均，92.59 ± 10.23 Hz），并且发作前 HFOs 和发作期 HFOs 之间有明显的带通边界。GC 分析显示 5 名患者（2、4、5、6 和 7），无论是发作前还是发作状态，SOZ 本身的 GC 程度最高。其余患者（1、3、8、9 和 10）在 SOZ 中的 GC 程度最高，其相邻区域处于发作前和发作期。GC 分析进一步证实了 WT 的结果，并表明 HFO 主要在局部大脑区域启动和传播，然后传输到相邻的大脑区域。