Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
Clin Neurophysiol. 2019 Sep;130(9):1596-1603. doi: 10.1016/j.clinph.2019.05.029. Epub 2019 Jun 22.
Focal cortical dysplasia (FCD) II is a frequently observed histopathological substrate in epilepsy surgery. In the present study, we explored the spatial distribution of epileptogenic activities across FCD II lesions using stereoelectroencephalography.
Patients with histopathologically confirmed type II FCDs and who had at least one depth electrode that go through the wall of the dysplastic sulcus from the surface to the bottom were included. The dysplastic sulci were divided into the bottom and non-bottom parts manually, and contacts were defined as bottom or non-bottom contacts according to their locations. Factors (bottom location, pathological subtype, magnetic resonance imaging manifestation, and presence of bottom-of-sulcus dysplasia) potentially associated with earliest onset identified by conventional visual analysis, epileptogenicity index (EI), and standardized number of high-frequency oscillations (HFOs) were analyzed. Linear regression analyses between distance (from the location of the analyzed contact to the bottom of the sulcus) and EI value and HFO number were performed.
Sixteen patients with 19 depth electrodes containing 112 valid contacts were included. Bottom location was the sole factor significantly associated with earliest onset (P < 0.001), EI value (P < 0.001), and HFO number (P < 0.001). Most earliest onsets were recorded by the bottom contacts, bottom contacts had higher EI value (0.81 ± 0.28 vs. 0.31 ± 0.24, P < 0.001) and more HFOs (0.78 ± 0.28 vs. 0.35 ± 0.31, P < 0.001) than non-bottom contacts. Moreover, the EI value (R = -0.72, P < 0.001) and HFO number (R = -0.64, P < 0.001) were significantly negatively correlated with distance, regardless of histopathological subtype, MRI manifestation, or absence of bottom-of-sulcus dysplasia.
Seizure onsets and interictal HFOs most often arise from the bottom part of a sulcus with type II FCD.
The findings of the present study contribute to intracranial electrode selection, trajectory planning, and, later on, resection of this kind of malformation.
局灶性皮质发育不良（FCD）Ⅱ型是癫痫手术中常见的组织病理学基础。本研究通过立体脑电图（SEEG）探讨 FCD Ⅱ病变内致痫活动的空间分布。
纳入经组织病理学证实为 FCDⅡ型且至少有一个深部电极从皮质表面穿过病变沟回到达底部的患者。手动将病变沟回分为底部和非底部两部分，根据电极位置定义为底部或非底部电极。分析常规视觉分析、致痫性指数（EI）和高频振荡（HFO）标准化数量识别的最早起始的潜在相关因素（底部位置、病理亚型、磁共振成像表现和沟回底部发育不良）。对距离（分析电极位置到沟回底部的距离）与 EI 值和 HFO 数量进行线性回归分析。
纳入 16 例患者，19 个深部电极共 112 个有效电极。底部位置是唯一与最早起始显著相关的因素（P<0.001），与 EI 值（P<0.001）和 HFO 数量（P<0.001）也显著相关。大多数最早起始起源于底部电极，底部电极的 EI 值（0.81±0.28 比 0.31±0.24，P<0.001）和 HFO 数量（0.78±0.28 比 0.35±0.31，P<0.001）均显著高于非底部电极。此外，EI 值（R=-0.72，P<0.001）和 HFO 数量（R=-0.64，P<0.001）与距离呈显著负相关，与病理亚型、MRI 表现或沟回底部发育不良无关。
癫痫发作和发作间期 HFO 最常起源于 FCDⅡ型的沟回底部。
本研究的发现有助于颅内电极选择、轨迹规划，以及随后对这种畸形的切除。
