Impaired consciousness in temporal lobe seizures: role of cortical slow activity
Impaired consciousness in temporal lobe seizures: role of cortical slow activity
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DOI：
10.1093/brain/awq316
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发表时间：
2010-12-01
期刊：
影响因子：
14.5
通讯作者：
Blumenfeld, Hal
中科院分区：
文献类型：
--
作者：
Englot, Dario J.;Yang, Li;Blumenfeld, Hal
意识受损需要改变大脑皮层功能。这可以直接发生在损害广泛的双侧皮层区域的疾病中，也可以间接通过影响皮层下唤醒系统而发生。因此，为什么局灶性颞叶癫痫发作经常损害意识，这一直是一个令人困惑的问题。早期的研究表明，意识改变可能发生在双侧或显性颞叶癫痫发作。然而，其他双侧颞叶疾病不会损害意识。最近的研究支持了一个“网络抑制假说”，即颞叶癫痫发作破坏了脑干间脑唤醒系统，间接导致皮质功能下降和意识受损。事实上，先前的研究显示皮质下参与颞叶癫痫发作和颅内脑电图双侧额顶叶慢波活动。然而，额顶叶慢波和意识障碍之间的关系，以及皮质减慢和快速癫痫发作活动之间的关系还没有直接调查。我们分析了26例经手术证实的内侧颞叶癫痫患者63次部分性发作的颅内脑电图记录。基于癫痫发作期间视频的盲态审查确定行为反应性，并将其分类为受损（复杂部分性癫痫发作）或未受损（简单部分性癫痫发作）。我们观察到在复杂部分性癫痫发作期间，与简单部分性癫痫发作相比，双侧额叶和顶叶新皮层的δ范围1-2 Hz慢波活动显著增加。此外，我们证实了以前的工作表明，传播单侧内侧颞叶快速发作活动的双侧颞叶是显着更大的复杂部分比简单部分癫痫发作。有趣的是，我们发现额顶叶慢波活动的信号功率与每个半球的颞叶快速发作活动显著相关。最后，我们观察到复杂部分性癫痫发作在语言主导型颞叶中更为常见。这些发现为颞叶癫痫时意识受损相关的双侧额顶叶慢波形式的皮质功能障碍提供了直接证据。我们假设双侧颞叶癫痫发作可能对皮层下唤醒系统产生强大的抑制作用。需要进一步的研究来充分确定皮质-皮质下网络在发作性新皮质功能障碍中的作用，并可能揭示预防颞叶癫痫这一重要负面后果的治疗方法。
Impaired consciousness requires altered cortical function. This can occur either directly from disorders that impair widespread bilateral regions of the cortex or indirectly through effects on subcortical arousal systems. It has therefore long been puzzling why focal temporal lobe seizures so often impair consciousness. Early work suggested that altered consciousness may occur with bilateral or dominant temporal lobe seizure involvement. However, other bilateral temporal lobe disorders do not impair consciousness. More recent work supports a 'network inhibition hypothesis' in which temporal lobe seizures disrupt brainstem-diencephalic arousal systems, leading indirectly to depressed cortical function and impaired consciousness. Indeed, prior studies show subcortical involvement in temporal lobe seizures and bilateral frontoparietal slow wave activity on intracranial electroencephalography. However, the relationships between frontoparietal slow waves and impaired consciousness and between cortical slowing and fast seizure activity have not been directly investigated. We analysed intracranial electroencephalography recordings during 63 partial seizures in 26 patients with surgically confirmed mesial temporal lobe epilepsy. Behavioural responsiveness was determined based on blinded review of video during seizures and classified as impaired (complex-partial seizures) or unimpaired (simple-partial seizures). We observed significantly increased delta-range 1-2 Hz slow wave activity in the bilateral frontal and parietal neocortices during complex-partial compared with simple-partial seizures. In addition, we confirmed prior work suggesting that propagation of unilateral mesial temporal fast seizure activity to the bilateral temporal lobes was significantly greater in complex-partial than in simple-partial seizures. Interestingly, we found that the signal power of frontoparietal slow wave activity was significantly correlated with the temporal lobe fast seizure activity in each hemisphere. Finally, we observed that complex-partial seizures were somewhat more common with onset in the language-dominant temporal lobe. These findings provide direct evidence for cortical dysfunction in the form of bilateral frontoparietal slow waves associated with impaired consciousness in temporal lobe seizures. We hypothesize that bilateral temporal lobe seizures may exert a powerful inhibitory effect on subcortical arousal systems. Further investigations will be needed to fully determine the role of cortical-subcortical networks in ictal neocortical dysfunction and may reveal treatments to prevent this important negative consequence of temporal lobe epilepsy.