Krembil Neuroscience Centre, Division of Neurology, Toronto Western Hospital, University of Toronto, 399 Bathurst Street, Toronto, ON, Canada M5T 2S8.
Clin Neurophysiol. 2011 Jul;122(7):1295-313. doi: 10.1016/j.clinph.2010.11.019. Epub 2011 Feb 2.
There is persistent debate as to whether or not EEG and MEG recordings in patients with mesial temporal lobe epilepsy (MTLE) can detect mesial temporal interictal epileptiform discharges (spikes), and this issue is particularly relevant for source localization studies. With the aim of providing direct evidence pertinent to this debate we present detailed examples of the intracranial sources of spikes recorded with EEG and MEG in MTLE.
Spikes recorded in five different patients with MTLE during intracranial EEG (n=2), intraoperative electrocorticography (ECOG; n=1), combined scalp-intracranial EEG (n=2) and combined EEG-MEG (n=1) were analyzed and the intracranial sources of the spike foci were matched with their corresponding extracranial EEG and/or MEG fields. EEG and MEG dipole source localization was performed on six independent spike foci identified in one representative patient with bilateral MTLE.
Spikes with an electrical field maximal at F7/8, F9/10≥T3/4 were generated in the anterolateral temporal neocortex. The absence of coincident spiking at mesial locations indicated that these were not propagated from or to the hippocampus. Spikes with an electrical field maximal at T3/4≥T9/10 were generated in the lateral temporal neocortex and likewise did not involve the hippocampus. Individual spikes generated in the mesiobasal temporal neocortex, including the fusiform gyrus, were difficult to detect with EEG (low amplitude diphasic waves most apparent after spike averaging at T3/4, T9/10≥T5/6, P9/10) and only slightly more identifiable with MEG. Spikes generated within and confined to the mesial temporal structures, as confirmed by intracranial recordings, could not be detected with EEG or MEG. Notably, such spikes could not be detected even at intracranial recording sites on the lateral surface of the temporal lobe.
We present detailed evidence in a small case series showing that typical anterior temporal spikes recorded with EEG and MEG in MTLE arose from the anterolateral temporal neocortex and were neither propagated from nor to the hippocampus. Mid temporal EEG spikes were localized to the lateral temporal neocortex. Intracranially detected mesial temporal spikes were not detected with EEG or MEG.
The spikes recorded with EEG and MEG in MTLE are localized to neocortical foci, and not to the mesial temporal structures. Current noninvasive EEG and MEG source localization studies cannot accurately identify true mesial temporal spikes.
关于内侧颞叶癫痫（MTLE）患者的脑电图（EEG）和脑磁图（MEG）记录是否能检测到内侧颞叶间发性癫痫样放电（棘波），一直存在争议，这个问题对于源定位研究尤为重要。为了提供与这一争论相关的直接证据，我们展示了在 MTLE 中使用 EEG 和 MEG 记录的棘波的颅内源的详细示例。
对 5 例 MTLE 患者在颅内 EEG（n=2）、术中皮质电图（ECOG；n=1）、头皮-颅内 EEG 联合（n=2）和 EEG-MEG 联合（n=1）期间记录的棘波进行了分析，并将棘波焦点的颅内源与相应的颅外 EEG 和/或 MEG 场相匹配。对一位双侧 MTLE 的代表性患者的 6 个独立棘波焦点进行了 EEG 和 MEG 偶极子源定位。
在 F7/8、F9/10≥T3/4 处电场最大的棘波产生于前外侧颞叶新皮质。在中侧位置没有同时出现棘波，表明它们不是从海马体传播来的，也不是传播到海马体的。在 T3/4≥T9/10 处电场最大的棘波产生于外侧颞叶新皮质，同样也不涉及海马体。来自中侧颞叶新皮质的单个棘波，包括梭状回，很难用 EEG 检测到（在 T3/4、T9/10≥T5/6、P9/10 处，低幅度双相波最明显，经过棘波平均后才可以检测到），用 MEG 检测到的也只是稍微多一点。在颅内记录证实的情况下，局限于内侧颞叶结构内的棘波，无法用 EEG 或 MEG 检测到。值得注意的是，即使在颞叶外侧表面的颅内记录部位也无法检测到这些棘波。
我们在一个小的病例系列中提供了详细的证据，表明在 MTLE 中用 EEG 和 MEG 记录的典型前颞叶棘波起源于前外侧颞叶新皮质，既不是从海马体传播来的，也不是传播到海马体的。中颞叶 EEG 棘波定位于外侧颞叶新皮质。用颅内检测到的内侧颞叶棘波无法用 EEG 或 MEG 检测到。
在 MTLE 中用 EEG 和 MEG 记录的棘波定位于皮质焦点，而不是内侧颞叶结构。目前的非侵入性 EEG 和 MEG 源定位研究不能准确识别真正的内侧颞叶棘波。
