Superficial and deep white matter diffusion abnormalities in focal epilepsies

Area of Science:

• Neuroimaging
• Neurology
• Diffusion Tensor Imaging

Background:

• Focal epilepsies exhibit diverse etiologies and clinical presentations.
• Understanding white matter (WM) microstructural abnormalities is crucial for characterizing epilepsy subtypes.
• Diffusion Tensor Imaging (DTI) offers insights into WM integrity.

Purpose of the Study:

• To evaluate superficial and deep WM DTI metrics in focal epilepsies.
• To identify distinct patterns of microstructural abnormalities based on epilepsy etiology, location, and treatment response.
• To compare WM abnormalities between temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) and focal cortical dysplasia (FCD).

Main Methods:

• Examined DTI data from 113 healthy controls and 113 patients with focal epilepsies (TLE-HS, FCD).
• Utilized multicontrast multiatlas parcellation for WM microstructure assessment.
• Evaluated fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) in regions of interest (ROIs).

Main Results:

• TLE-HS groups exhibited more widespread superficial and deep WM diffusion abnormalities than FCD groups.
• Superficial WM abnormalities in TLE-HS were multilobar and ipsilateral/contralateral, with less distribution in responsive patients.
• FCD patients showed diffusion changes primarily adjacent to epileptogenic areas.

Conclusions:

• Findings support widespread WM diffusion abnormalities in TLE-HS compared to other focal epilepsies.
• Superficial WM damage in FCD is restricted, while TLE-HS shows diffuse damage with frontotemporal predominance.
• Superficial WM analysis may enhance understanding of epilepsy mechanisms, network dysfunction, and subtle FCD diagnosis.