1Epilepsy Center.
2MEG Center, and.
Neurosurg Focus. 2020 Apr 1;48(4):E15. doi: 10.3171/2020.1.FOCUS19791.
Generalized-onset seizures are usually conceptualized as engaging bilaterally distributed networks with no clear focus. However, the authors previously reported a case series demonstrating that in some patients with generalized-onset seizures, focal seizure onset could be discovered after corpus callosotomy. The corpus callosum is considered to be a major pathway for seizure generalization in this group of patients. The authors hypothesized that, in patients with generalized-onset seizures, the structure of the corpus callosum could be different between patients who have lateralized seizures and those who have nonlateralized seizures after corpus callosotomy. The authors aimed to evaluate the structural difference through statistical analysis of diffusion tensor imaging (DTI) scalars between these two groups of patients.
Thirty-two patients diagnosed with generalized-onset motor seizures and without an MRI lesion were included in this study. Among them, 16 patients developed lateralized epileptic activities after corpus callosotomy, and the remaining 16 patients continued to have nonlateralized seizures after corpus callosotomy. Presurgical DTI studies were acquired to quantify the structural integrity of the corpus callosum.
The DTI analysis showed significant reduction of fractional anisotropy (FA) and increase in radial diffusivity (RD) in the body of the corpus callosum in the lateralized group compared with the nonlateralized group.
The authors' findings indicate the existence of different configurations of bilateral epileptic networks in generalized epilepsy. Generalized seizures with focal onset relying on rapid spread through the corpus callosum might cause more structural damage related to demyelination in the corpus callosum, showing reduced FA and increased RD. This study suggests that presurgical DTI analysis of the corpus callosum might predict the seizure lateralization after corpus callosotomy.
全面性发作性癫痫通常被认为涉及双侧分布的网络，没有明确的焦点。然而，作者之前报告了一系列病例，表明在一些全面性发作性癫痫患者中，在胼胝体切开术后可能会发现局灶性发作起始。胼胝体被认为是这群患者癫痫发作泛化的主要途径。作者假设，在全面性发作性癫痫患者中，胼胝体的结构在胼胝体切开术后发生局灶性发作的患者和非局灶性发作的患者之间可能存在差异。作者旨在通过对这两组患者的弥散张量成像（DTI）标量进行统计分析来评估结构差异。
本研究纳入了 32 名诊断为全面性运动性癫痫且无 MRI 病变的患者。其中，16 名患者在胼胝体切开术后出现局灶性癫痫活动，其余 16 名患者在胼胝体切开术后继续出现非局灶性癫痫。术前进行 DTI 研究以量化胼胝体的结构完整性。
DTI 分析显示，与非局灶性组相比，局灶性组胼胝体体部的各向异性分数（FA）降低，径向扩散系数（RD）升高。
作者的发现表明，全面性癫痫中存在双侧癫痫网络的不同构型。依赖于胼胝体快速传播的局灶性起始的全面性发作可能导致胼胝体与脱髓鞘相关的结构损伤更多，表现为 FA 降低和 RD 增加。这项研究表明，术前胼胝体 DTI 分析可能预测胼胝体切开术后的癫痫侧化。
