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Updated: Mar 27, 2026
Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Network specific change in white matter integrity in mesial temporal lobe epilepsy
Hisaji Imamura1, Riki Matsumoto2, Shigetoshi Takaya3
1Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
Objectives:
To identify the specific change of white matter integrity that occurs in the brain network related to epileptic activity in patients with mesial temporal lobe epilepsy (MTLE).
Methods:
We recruited 18 patients with MTLE and 18 healthy subjects. In MTLE patients, the remote functional-deficit zone was delineated using fluorodeoxyglucose positron emission tomography as an extratemporal region showing glucose hypometabolism. Using diffusion magnetic resonance imaging tractography, we defined a seizure propagation tract (PT) as a white matter pathway that connects the focus with a remote functional deficit zone. We also used the corticospinal tract (CST) and inferior longitudinal fasciculus (ILF) as control tracts in the hemisphere ipsilateral to the focus. Fractional anisotropy (FA), mean diffusivity (MD), and volume of the tracts were compared among PT, CST, and ILF.
Results:
Tractographic analysis identified the uncinate fasciculus, arcuate fasciculus, and fornix as PTs. A decrease in FA was found in MTLE patients compared with healthy subjects in all tracts, but PTs showed a more significant decrease in FA than did the two control tracts. Although the change in MD was also found in MTLE patients compared with healthy controls, a tract-specific change was not observed. Although white-matter damage was observed in all candidate tracts examined, the integrity of white matter was most significantly decreased in PTs in MTLE.
Conclusion:
The change in white matter integrity occurs specifically in the pathways that connect the focus and remote functional deficit zones in patients with MTLE, i.e., the pathways that are assume to be associated with seizure propagation.
Insights
White matter integrity specifically decreases in seizure propagation pathways in mesial temporal lobe epilepsy (MTLE) patients. This finding highlights key brain network changes related to epileptic activity.
Area of Science:
- Neuroimaging
- Epileptology
- Neuroscience
Background:
- Mesial temporal lobe epilepsy (MTLE) involves complex brain network dysfunction.
- Understanding white matter changes is crucial for characterizing epileptic activity.
Purpose of the Study:
- To identify specific white matter integrity alterations in the brain network associated with epileptic activity in MTLE patients.
- To investigate the role of white matter pathways in seizure propagation.
Main Methods:
- Diffusion MRI tractography was used to define seizure propagation tracts (PTs) and control tracts (CST, ILF).
- Fractional anisotropy (FA) and mean diffusivity (MD) were compared between MTLE patients and healthy controls.
- Fluorodeoxyglucose positron emission tomography (FDG-PET) identified remote functional deficit zones.
Main Results:
- Tractographic analysis identified the uncinate fasciculus, arcuate fasciculus, and fornix as PTs.
- MTLE patients showed decreased FA in all examined tracts compared to controls.
- PTs exhibited a more significant decrease in FA, indicating specific white matter damage in seizure propagation pathways.
Conclusions:
- White matter integrity changes are specific to pathways connecting the epileptic focus and remote deficit zones in MTLE.
- These findings suggest that altered white matter integrity in propagation pathways is a key feature of MTLE.
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