Identification of pre-spike network in patients with mesial temporal lobe epilepsy

Faizo, Nahla L., Burianová, Hana, Gray, Marcus, Hocking, Julia, Galloway, Graham and Reutens, David (2014) Identification of pre-spike network in patients with mesial temporal lobe epilepsy. Frontiers in Neurology, 5 222.1-222.8. doi:10.3389/fneur.2014.00222


Author Faizo, Nahla L.
Burianová, Hana
Gray, Marcus
Hocking, Julia
Galloway, Graham
Reutens, David
Title Identification of pre-spike network in patients with mesial temporal lobe epilepsy
Journal name Frontiers in Neurology   Check publisher's open access policy
ISSN 1664-2295
Publication date 2014-10-28
Sub-type Article (original research)
DOI 10.3389/fneur.2014.00222
Open Access Status DOI
Volume 5
Start page 222.1
End page 222.8
Total pages 8
Place of publication Lausanne, Switzerland
Publisher Frontiers Research Foundation
Collection year 2015
Language eng
Formatted abstract
Background: Seizures and interictal spikes in mesial temporal lobe epilepsy (MTLE) affect a network of brain regions rather than a single epileptic focus. Simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) studies have demonstrated a functional network in which hemodynamic changes are time-locked to spikes. However, whether this reflects the propagation of neuronal activity from a focus, or conversely the activation of a network linked to spike generation remains unknown. The functional connectivity (FC) changes prior to spikes may provide information about the connectivity changes that lead to the generation of spikes. We used EEG-fMRI to investigate FC changes immediately prior to the appearance of interictal spikes on EEG in patients with MTLE.

Methods/principal findings: Fifteen patients with MTLE underwent continuous EEG-fMRI during rest. Spikes were identified on EEG and three 10 s epochs were defined relative to spike onset: spike (0–10 s), pre-spike (−10 to 0 s), and rest (−20 to −10 s, with no previous spikes in the preceding 45s). Significant spike-related activation in the hippocampus ipsilateral to the seizure focus was found compared to the pre-spike and rest epochs. The peak voxel within the hippocampus ipsilateral to the seizure focus was used as a seed region for FC analysis in the three conditions. A significant change in FC patterns was observed before the appearance of electrographic spikes. Specifically, there was significant loss of coherence between both hippocampi during the pre-spike period compared to spike and rest states.

Conclusion/significance: In keeping with previous findings of abnormal inter-hemispheric hippocampal connectivity in MTLE, our findings specifically link reduced connectivity to the period immediately before spikes. This brief decoupling is consistent with a deficit in mutual (inter-hemispheric) hippocampal inhibition that may predispose to spike generation.
Keyword Interictal spikes
Hippocampus
Mesial temporal lobe epilepsy
EEG-fMRI
Functional connectivity
Network
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Open access journal

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
Centre for Advanced Imaging Publications
 
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Created: Thu, 30 Oct 2014, 10:55:40 EST by Shona Osborne on behalf of Centre for Advanced Imaging