Diffusion Tensor Imaging as a Preliminary Study of White Matter Associations with Surgical Outcome in Mesial Temporal Lobe Epilepsy

This study evaluates pre-surgery white matter abnormalities in evaluating the association between pre-surgical white matter integrity and post-surgery outcomes at the group level using Diffusion Tensor Imaging (DTI) in patients with Mesial Temporal Lobe Epilepsy (MTLE), specifically examining the differences between seizure-free and non-seizure-free patients, by Regions of Interest (ROIs) and diffusion parameters (biomarkers).

A retrospective analysis was conducted on pre-surgical DTI data from MTLE patients who underwent amygdalohippocampectomy with the subject outcome evaluation. Key parameters, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusion (AD), and radial diffusion (RD), were extracted from regions of interest (ROIs) such as the hippocampus, thalamus, and temporal pole. Statistical analysis included ANOVA with Bonferroni post-hoc tests to compare surgical responders and non-responders on the ipsilateral and contralateral sides of the epileptogenic zone, as per clinical convention.

FA values in the contralateral hippocampus and thalamus were significantly lower in the Not-SF group compared to the SF group (p< 0.05). RD values in the contralateral hippocampus and temporal pole were significantly higher in the Not-SF group (p< 0.05). In ipsilateral regions, MD and RD values in the hippocampus and temporal pole were significantly higher in the Not-SF group (p< 0.01), while FA values were significantly lower (p< 0.001). AD did not show significant differences. Overall, increased RD and MD and reduced FA in the Not-SF group indicate reduced microstructural integrity associated with poor seizure control.

This study demonstrates that diffusion-based structural connectivity analysis can distinguish seizure-free from non–seizure-free TLE patients, highlighting the clinical relevance of hippocampus–temporal pole and hippocampus–thalamus pathways in postoperative outcomes. By extending diffusion evaluation beyond traditional tracts and integrating modern segmentation and tractography tools, our findings support the role of TLE as a network disorder and emphasize the potential of advanced DTI methods for understanding the network-level changes associated with surgical outcomes.

This study shows that diffusion-based structural connectivity metrics, particularly within hippocampus–temporal pole and hippocampus–thalamus pathways, showed exploratory associations with surgical outcomes in MTLE patients. While these metrics suggest differences between outcome groups, these findings are hypothesis-generating.