Altered structural and functional thalamocortical networks in secondarily generalized extratemporal lobe seizures

Area of Science:

• Neuroimaging
• Epileptology
• Neuroscience

Background:

• Thalamocortical network abnormalities are known in primary generalized and mesial temporal lobe epilepsies.
• Limited research exists on thalamocortical network profiles in secondary generalized seizures from focal neocortical origins.

Purpose of the Study:

• To investigate structural and functional alterations in the thalamocortical network of patients with secondarily generalized extratemporal lobe seizures.
• To compare neuroimaging findings in MRI-negative epilepsy patients with healthy controls.

Main Methods:

• Utilized high-resolution T1-weighted, diffusion-tensor, and resting-state functional MRI (rs-fMRI).
• Employed voxel-based morphometry (VBM) for gray matter (GM) density and fractional anisotropy (FA) analysis.
• Performed rs-fMRI analysis seeding from the thalamus to assess functional connectivity.

Main Results:

• Significantly decreased GM density in the thalamus and frontal gyri observed in patients.
• Reduced white matter (WM) FA in the bilateral anterior corona radiata identified.
• Altered thalamocortical functional connectivity with various cortices, particularly prefrontal regions.

Conclusions:

• Secondarily generalized seizures from focal cortical sources are linked to structural and functional thalamocortical network changes.
• Findings indicate involvement of the mediodorsal thalamic nucleus.
• Paradoxical correlation between disease duration and functional connectivity strength was noted.