Temporal lobe epilepsy alters spatio-temporal dynamics of the hippocampal functional network

Subcutaneous recording using electroencephalography (EEG) has the potential to enable ultra-long-term epilepsy monitoring in real-life conditions because it allows the patient increased mobility and discreteness. This study is the first to compare physiological and epileptiform EEG signals from subcutaneous and scalp EEG recordings in epilepsy patients. Four patients with probable or definite temporal lobe epilepsy were monitored with simultaneous scalp and subcutaneous EEG recordings. EEG recordings were compared by correlation and time-frequency analysis across an array of clinically relevant waveforms and patterns. We found high similarity between the subcutaneous EEG channels and nearby temporal scalp channels for most investigated electroencephalographic events. In particular, the temporal dynamics of one typical temporal lobe seizure in one patient were similar in scalp and subcutaneous recordings in regard to frequency distribution and morphology. Signal similarity is strongly related to the distance between the subcutaneous and scalp electrodes. On the basis of these limited data, we conclude that subcutaneous EEG recordings are very similar to scalp recordings in both time and time-frequency domains, if the distance between them is small. As many electroencephalographic events are local/regional, the positioning of the subcutaneous electrodes should be considered carefully to reflect the relevant clinical question. The impact of implantation depth of the subcutaneous electrode on recording quality should be investigated further. NEW & NOTEWORTHY This study is the first publication comparing the detection of clinically relevant, pathological EEG features from a subcutaneous recording system designed for out-patient ultra-long-term use to gold standard scalp EEG recordings. Our study shows that subcutaneous channels are very similar to comparable scalp channels, but also point out some issues yet to be resolved.

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Disrupted functional network in patients with temporal lobe epilepsy with impaired alertness

Epilepsy & Behavior ◽

10.1016/j.yebeh.2019.106573 ◽

2019 ◽

Vol 101 ◽

pp. 106573

Author(s):

Jinping Liu ◽

Xia Zhou ◽

Zhao Zhang ◽

Lu Qin ◽

Wei Ye ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Functional Network

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Altered static and dynamic functional network connectivity in temporal lobe epilepsy with different disease duration and their relationships with attention

Journal of Neuroscience Research ◽

10.1002/jnr.24915 ◽

2021 ◽

Author(s):

Xiulin Liang ◽

Xiaomin Pang ◽

Jingyuan Zhao ◽

Lu Yu ◽

Peirong Wu ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Disease Duration ◽

Network Connectivity ◽

Functional Network ◽

Functional Network Connectivity ◽

Dynamic Functional Network Connectivity

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Epileptogenic Zone Location of Temporal Lobe Epilepsy by Cross-Frequency Coupling Analysis

Frontiers in Neurology ◽

10.3389/fneur.2021.764821 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xiaotong Liu ◽

Fang Han ◽

Rui Fu ◽

Qingyun Wang ◽

Guoming Luan

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Single Channel ◽

Brain Networks ◽

Brain Regions ◽

Functional Network ◽

Epileptogenic Zone ◽

Coupling Analysis ◽

Frequency Coupling ◽

Cross Frequency Coupling

Epilepsy is a chronic brain disease with dysfunctional brain networks, and electroencephalography (EEG) is an important tool for epileptogenic zone (EZ) identification, with rich information about frequencies. Different frequency oscillations have different contributions to brain function, and cross-frequency coupling (CFC) has been found to exist within brain regions. Cross-channel and inter-channel analysis should be both focused because they help to analyze how epilepsy networks change and also localize the EZ. In this paper, we analyzed long-term stereo-electroencephalography (SEEG) data from 17 patients with temporal lobe epilepsy. Single-channel and cross-channel CFC features were combined to establish functional brain networks, and the network characteristics under different periods and the localization of EZ were analyzed. It was observed that theta–gamma phase amplitude coupling (PAC) within the electrodes in the seizure region increased during the ictal (p < 0.05). Theta–gamma and delta–gamma PAC of cross-channel were enhanced in the early and mid-late ictal, respectively. It was also found that there was a strong cross-frequency coupling state between channels of EZ in the functional network during the ictal, along with a more regular network than interictal. The accuracy rate of EZ localization was 82.4%. Overall, the combination of single-channel and multi-channel cross-band coupling analysis can help identify seizures and localize EZ for temporal lobe epilepsy. Rhythmic coupling reveals a relationship between the functional network and the seizure status of epilepsy.

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Mapping the Spatio-Temporal Pattern of the Mammalian Target of Rapamycin (mTOR) Activation in Temporal Lobe Epilepsy

PLoS ONE ◽

10.1371/journal.pone.0039152 ◽

2012 ◽

Vol 7 (6) ◽

pp. e39152 ◽

Cited By ~ 48

Author(s):

Long-Ze Sha ◽

Xiao-Liang Xing ◽

Dan Zhang ◽

Yuan Yao ◽

Wan-Chen Dou ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Temporal Pattern ◽

Mammalian Target Of Rapamycin ◽

Target Of Rapamycin ◽

Spatio Temporal

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Different Functional Network Connectivity Patterns in Epilepsy: A Rest-State fMRI Study on Mesial Temporal Lobe Epilepsy and Benign Epilepsy With Centrotemporal Spike

Frontiers in Neurology ◽

10.3389/fneur.2021.668856 ◽

2021 ◽

Vol 12 ◽

Author(s):

Cong Fu ◽

Aikedan Aisikaer ◽

Zhijuan Chen ◽

Qing Yu ◽

Jianzhong Yin ◽

...

Keyword(s):

Functional Connectivity ◽

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Mesial Temporal Lobe Epilepsy ◽

Functional Network ◽

Cortical Networks ◽

Subcortical Region ◽

Subcortical Nuclei ◽

Mesial Temporal Lobe ◽

Benign Epilepsy

The stark discrepancy in the prognosis of epilepsy is closely related to brain damage features and underlying mechanisms, which have not yet been unraveled. In this study, differences in the epileptic brain functional connectivity states were explored through a network-based connectivity analysis between intractable mesial temporal lobe epilepsy (MTLE) patients and benign epilepsy with centrotemporal spikes (BECT). Resting state fMRI imaging data were collected for 14 MTLE patients, 12 BECT patients and 16 healthy controls (HCs). Independent component analysis (ICA) was performed to identify the cortical functional networks. Subcortical nuclei of interest were extracted from the Harvard-Oxford probability atlas. Network-based statistics were used to detect functional connectivity (FC) alterations across intranetworks and internetworks, including the connectivity between cortical networks and subcortical nuclei. Compared with HCs, MTLE patients showed significant lower activity between the connectivity of cortical networks and subcortical nuclei (especially hippocampus) and lower internetwork FC involving the lateral temporal lobe; BECT patients showed normal cortical-subcortical FC with hyperconnectivity between cortical networks. Together, cortical-subcortical hypoconnectivity in MTLE suggested a low efficiency and collaborative network pattern, and this might be relevant to the final decompensatory state and the intractable prognosis. Conversely, cortical-subcortical region with normal connectivity remained well in global cooperativity, and compensatory internetwork hyperconnectivity caused by widespread cortical abnormal discharge, which might account for the self-limited clinical outcome in BECT. Based on the fMRI functional network study, different brain network patterns might provide a better explanation of mechanisms in different types of epilepsy.

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