Altered White Matter Structural Network in Frontal and Temporal Lobe Epilepsy: A Graph-Theoretical Study

Area of Science:

• Neuroscience
• Medical Imaging
• Epileptology

Background:

• Focal cortical dysplasias (FCDs) are common causes of drug-resistant epilepsy, particularly in the temporal and frontal lobes.
• Temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE) represent major subgroups of partial epilepsy.
• Understanding the underlying white matter network alterations is crucial for comprehending cognitive deficits in these conditions.

Purpose of the Study:

• To investigate white matter structural network differences in patients with FLE and TLE caused by FCDs using graph theory.
• To evaluate the relationship between network attributes, clinical factors (age of onset, disease duration), and cognitive function (MoCA-BC scores).

Main Methods:

• Diffusion tensor imaging (DTI) data from FLE, TLE, and healthy control (HC) groups were analyzed using graph theory (PANDA, GRETNA).
• Nonparametric ANCOVA was used to compare diffusion metrics and network attributes.
• Spearman partial correlation analysis examined associations between network attributes and clinical/cognitive variables.

Main Results:

• Both FLE and TLE groups exhibited widespread white matter structural network impairments extending beyond the FCD location.
• Similarities in white matter alterations between FLE and TLE suggest shared impact on fronto-temporal and thalamo-occipital connections, potentially causing overlapping cognitive deficits.
• White matter impairments were more severe in FLE compared to TLE, possibly due to greater involvement of Default Mode Network (DMN) nodes.

Conclusions:

• Epileptogenic networks in FLE and TLE lead to extensive white matter damage affecting cognitive function.
• FLE presents with more severe white matter network disruptions than TLE.
• Graph theory analysis of DTI provides insights into the neurobiological underpinnings of cognitive deficits in focal epilepsies.