Functional epileptic network in left mesial temporal lobe epilepsy detected using resting fMRI

Area of Science:

• Neuroimaging
• Epileptology
• Functional MRI

Background:

• Left temporal lobe epilepsy (TLE) is a common neurological disorder.
• Understanding the full extent of the epileptogenic network in TLE is crucial for treatment.
• Current fMRI techniques may not fully capture transient functional signal activity in TLE.

Purpose of the Study:

• To determine transient functional signal activity in TLE patients without EEG.
• To identify a possible whole-brain epileptogenic network in TLE using fMRI.
• To investigate functional connectivity patterns in TLE patients with controlled seizures.

Main Methods:

• Resting-state functional MRI (fMRI) scans were performed on five TLE patients and 10 healthy controls.
• A data-driven analysis (2dTCA) was used to calculate activation maps of functional signal peaks.
• fMRI functional connectivity analysis was conducted using the anterior hippocampal region as a seed.

Main Results:

• 2dTCA revealed activation in the left anterior hippocampus, bilateral insular cortex, and default-mode network in TLE patients.
• These findings are not commonly reported with fMRI but are supported by other studies.
• Functional connectivity analysis showed increased negative connectivity in TLE patients compared to controls across thalamic, brainstem, frontal, and parietal regions.

Conclusions:

• The study identified novel brain regions involved in TLE beyond the hippocampus.
• Increased negative connectivity suggests inhibited function in subcortical and cortical structures during ictal propagation.
• These findings contribute to understanding the complex, whole-brain epileptogenic network in TLE.