Hirozawa Daisuke, Terada Kiyohito, Matsuda Kazumi, Usui Keiko, Usui Naotaka, Tottori Takayasu, Kondo Akihiko, Araki Yasukiyo, Omote Yoshio, Kashida Yumi, Mochizuki Hideki, Inoue Yushi
*National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan; and †Department of Neurology, Osaka University, Osaka, Japan.
J Clin Neurophysiol. 2017 Sep;34(5):427-433. doi: 10.1097/WNP.0000000000000384.
Focal cortical dysplasia (FCD) is intrinsically epileptogenic, and an MRI-visible lesion typically constitutes the core part of the epileptogenic zone. We aimed to identify ictal EEG patterns that represent the epileptogenic zone by using subdural electrodes placed over the MRI-visible FCD lesion.
We selected seven patients with frontal lobe epilepsy caused by pathologically proven FCD type IIb who underwent preoperative intracranial EEG evaluation with subdural electrodes followed by resection surgery with seizure-free outcome. The characteristics of ictal EEG patterns, interictal/ictal high-frequency oscillations, and ictal direct current shifts from intracranial electrodes placed over the MRI-visible lesion were analyzed.
Two seizure-onset patterns (low voltage fast activity and fast spike activity) were identified. Low voltage fast activity was seen in all patients with a lateral frontal lesion, and it was always preceded by preictal spikes. Fast spike activity occurred only in patients with a mesial frontal lesion. Interictal/ictal high-frequency oscillations and ictal direct current shifts were seen in all patients.
The epileptogenic zone of frontal FCD type IIb may be characterized by EEG seizure-onset patterns consisting of low voltage fast activity and fast spike activity accompanied by ictal high-frequency oscillations and ictal direct current shifts. Further study is needed to determine whether other seizure-onset patterns exist in patients with FCD type IIb.
局灶性皮质发育不良（FCD）本质上具有致痫性，磁共振成像（MRI）可见的病变通常构成致痫区的核心部分。我们旨在通过在MRI可见的FCD病变上方放置硬膜下电极，识别代表致痫区的发作期脑电图模式。
我们选择了7例经病理证实为IIb型FCD所致额叶癫痫的患者，这些患者术前接受了硬膜下电极颅内脑电图评估，随后进行了切除手术，术后无癫痫发作。分析了放置在MRI可见病变上方的颅内电极的发作期脑电图模式、发作间期/发作期高频振荡以及发作期直流偏移的特征。
识别出两种发作起始模式（低电压快活动和快棘波活动）。低电压快活动在所有额叶外侧病变患者中均可见，且总是先于发作前棘波出现。快棘波活动仅出现在额叶内侧病变患者中。所有患者均可见发作间期/发作期高频振荡和发作期直流偏移。
IIb型额叶FCD的致痫区可能具有脑电图发作起始模式的特征，包括低电压快活动和快棘波活动，并伴有发作期高频振荡和发作期直流偏移。需要进一步研究以确定IIb型FCD患者中是否存在其他发作起始模式。
