Superficial and deep white matter abnormalities in temporal lobe epilepsy

Area of Science:

• Neuroimaging and Epilepsy Research
• White Matter Integrity in Neurological Disorders

Background:

• Non-invasive neuroimaging is crucial for identifying cerebral abnormalities in epilepsy.
• Reduced fractional anisotropy (FA) in deep white matter (WM) is a known marker in temporal lobe epilepsy (TLE).
• Abnormalities in superficial WM are less understood in epilepsy.

Purpose of the Study:

• To investigate diffusion-weighted imaging (DWI) abnormalities at varying WM depths in TLE.
• To compare superficial versus deep WM abnormalities in two independent TLE cohorts.
• To explore the clinical utility of WM abnormalities for lateralization, including in MRI-negative cases.

Main Methods:

• Analysis of two TLE cohorts (N=81 and N=70) with varying DWI acquisition schemes (multi-shell and single-shell).
• Registration of FA maps to a standard template for analysis of temporal WM.
• Comparison of FA measures at different WM depths, ipsilateral vs. contralateral WM, and MRI-positive vs. MRI-negative groups.

Main Results:

• Superficial WM exhibited significantly greater FA reductions compared to deep WM in TLE patients (P < 0.001).
• This superficial WM abnormality was more pronounced in the ipsilateral temporal lobe (P < 0.001).
• The observed effects were consistent across both TLE cohorts and present in MRI-negative patients.

Conclusions:

• Superficial WM is more affected than deep WM in temporal lobe epilepsy.
• WM FA abnormalities in superficial layers may aid in lateralizing epilepsy, even in MRI-negative individuals.
• Further research into the role of superficial WM in epilepsy pathogenesis and diagnosis is warranted.