Department of Neurology, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, South Korea.
Department of Medical Science, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, South Korea.
Epilepsia. 2018 Jan;59(1):215-225. doi: 10.1111/epi.13951. Epub 2017 Dec 4.
Patients with temporal lobe epilepsy (TLE) show brain connectivity changes in association with cognitive impairment. Seizure frequency and lateralization are 2 important clinical factors that characterize epileptic seizures. In this study, we sought to examine an interactive effect of the 2 seizure factors on intratemporal effective connectivity based on resting-state functional magnetic resonance imaging (rsfMRI) in patients with TLE.
For rsfMRI data acquired from 48 TLE patients and 45 healthy controls, we applied stochastic dynamical causal modeling to infer effective connectivity between 3 medial temporal lobe (MTL) regions, including the hippocampus (Hipp), parahippocampal gyrus (PHG), and amygdala (Amyg), ipsilateral to the seizure focus. We searched for the effect of the 2 seizure factors, seizure frequency (good vs poor seizure control) and lateralization (left vs right TLE), on connection strengths and their relationship with the level of verbal memory and language impairment.
Impairment of verbal memory and language function was mainly affected by seizure lateralization, consistent with preferential involvement of the left MTL in verbal mnemonic processing. For the fully connected model, which was selected as the effective connectivity structure that best explained the observed rsfMRI time series, alterations in connection strengths were primarily influenced by seizure frequency; there was an increase in the strength of the Hipp to PHG connection in TLE patients with poor seizure control, whereas the strength of the Amyg to PHG connection increased in those with good seizure control. Furthermore, the association between connection strength alterations and cognitive impairment was interactively affected by both seizure frequency and lateralization.
These findings suggest an interactive effect as well as an individual effect of seizure frequency and lateralization on neuroimaging features and cognitive function. This potential interaction needs to be evaluated in the consideration of multiple seizure factors.
颞叶癫痫（TLE）患者存在与认知障碍相关的脑连接变化。发作频率和偏侧化是描述癫痫发作的两个重要临床因素。在这项研究中，我们试图通过 TLE 患者的静息态功能磁共振成像（rsfMRI）来检查这两个发作因素对颞叶内侧（MTL）三个区域（包括海马（Hipp）、旁海马回（PHG）和杏仁核（Amyg））之间的内在时间有效连接的交互影响。
对于从 48 名 TLE 患者和 45 名健康对照者采集的 rsfMRI 数据，我们应用随机动力学因果建模来推断与致痫灶同侧的 3 个 MTL 区域（包括 Hipp、PHG 和 Amyg）之间的有效连接。我们搜索了两个发作因素（发作频率（控制良好 vs 控制不佳）和偏侧化（左 vs 右 TLE））对连接强度及其与言语记忆和语言障碍程度的关系的影响。
言语记忆和语言功能的损伤主要受发作偏侧化的影响，这与左 MTL 优先参与言语记忆加工相一致。对于完全连接模型，其被选为最佳解释观察到的 rsfMRI 时间序列的有效连接结构，连接强度的变化主要受发作频率的影响；在控制不佳的 TLE 患者中，Hipp 到 PHG 的连接强度增加，而在控制良好的患者中，Amyg 到 PHG 的连接强度增加。此外，连接强度变化与认知障碍之间的关联受到发作频率和偏侧化的交互影响。
这些发现表明，发作频率和偏侧化对神经影像学特征和认知功能既有单独的影响，也有交互的影响。在考虑多个发作因素时，需要对这种潜在的相互作用进行评估。
