Department of Neurosurgery, Epilepsy Center, Juntendo University, Tokyo, Japan.
Department of Neurosurgery, Epilepsy Center, Juntendo University, Tokyo, Japan; Division of Neurology, The Hospital for Sick Children, Toronto, Canada.
Seizure. 2022 Jan;94:23-25. doi: 10.1016/j.seizure.2021.11.006. Epub 2021 Nov 21.
The removal of the bottom of sulcus dysplasia (BOSD) often includes the gyral crown; however, this method has been controversial. We hypothesized that the epileptogenic zone of the BOSD does not include the gyral crown. To reveal the depth and extent of the epileptogenic zone of the BOSD, we applied the two electrophysiological modalities: (1) the occurrence rate (OR) of high-frequency oscillations (HFOs) and (2) modulation index (MI), reflecting the strength of phase-amplitude coupling between HFOs and slow oscillations.
We investigated the ripples [80-200 Hz] and fast ripples [200-300 Hz]) in HFOs and MI (HFOs [80-300 Hz] and slow oscillations [3-4 Hz]). We opened the sulcus at the BOSD and implanted the subdural electrodes directly over the MRI visible lesion. All patients (n = 3) underwent lesionectomy and the gyral crown was preserved.
Pathological findings demonstrated focal cortical dysplasia type IIb and seizure freedom was achieved. The OR of the HFOs was not significantly different between the BOSD and the gyral crown. In contrast, the MI between HFOs and slow oscillations in the BOSD was significantly higher than that in the gyral crown.
High MI values distinguished the epileptogenic BOSD from the non-epileptogenic gyral crowns. MI could be a more informative biomarker of epileptogenicity than the OR of HFOs in a subset of patients with the BOSD.
沟回发育不良（BOSD）的底部切除通常包括脑回顶部；然而，这种方法存在争议。我们假设 BOSD 的致痫区不包括脑回顶部。为了揭示 BOSD 的致痫区的深度和范围，我们应用了两种电生理模式：（1）高频振荡（HFOs）的发生率（OR）和（2）调制指数（MI），反映 HFOs 与慢波之间的相位-幅度耦合强度。
我们研究了 HFOs 中的锐波[80-200 Hz]和快波[200-300 Hz]以及 MI（HFOs [80-300 Hz]和慢波[3-4 Hz]）。我们在 BOSD 处打开脑沟，并将硬膜下电极直接植入 MRI 可见病变上方。所有患者（n=3）均接受了病变切除术，保留了脑回顶部。
病理检查显示 IIb 型局灶性皮质发育不良，且无癫痫发作。BOSD 和脑回顶部的 HFOs 的 OR 无显著差异。相比之下，BOSD 中 HFOs 与慢波之间的 MI 明显高于脑回顶部。
高 MI 值将致痫性 BOSD 与非致痫性脑回顶部区分开来。在 BOSD 的一部分患者中，MI 可能比 HFOs 的 OR 更能反映致痫性。
