White matter network disorder in mesial temporal epilepsy: An fMRI study

Area of Science:

• Neuroscience
• Epilepsy Research
• Functional Neuroimaging

Background:

• Mesial temporal lobe epilepsy (mTLE) is increasingly recognized as a network disorder.
• While cortical abnormalities are known, white matter (WM) network dysfunction in mTLE requires further investigation.
• Functional magnetic resonance imaging (fMRI) offers a novel approach to study WM functional activity.

Purpose of the Study:

• To investigate altered functional activities within WM networks in mTLE patients using fMRI.
• To explore the association between WM functional connectivity (FC) and widespread network dysfunction.
• To assess the utility of WM FC for seizure lateralization in mTLE.

Main Methods:

• Resting-state fMRI data were acquired from 39 mTLE patients and 29 healthy controls.
• Eleven WM networks were identified and their functional connectivity (FC) was analyzed.
• FC was compared between groups, and correlations with seizure frequency and lateralization were examined.

Main Results:

• mTLE patients exhibited decreased FC within deep WM networks compared to controls.
• Enhanced functional coupling was observed between deep WM networks and cortical regions involved in seizure propagation and interhemispheric disruption.
• FC between ipsilateral deep WM networks and specific cortical regions correlated positively with seizure frequency.
• Seizure onset zones were successfully lateralized in 33 out of 39 patients using WM FC.

Conclusions:

• Functional disruptions in WM networks extend beyond epileptogenic zones in mTLE, supporting the network disorder hypothesis.
• Deep WM networks are critical nodes implicated in the widespread network dysfunction observed in mTLE.
• WM functional connectivity is a promising imaging biomarker for mTLE diagnosis and seizure lateralization.