Neuroimaging signatures of mesial temporal lobe epilepsy: A coordinate-based meta-analysis of structural and resting-state functional imaging literature

Mesial temporal lobe epilepsy (MTLE) seizures are known to alter neural architecture, yet imaging studies report conflicting findings of their effects on the brain. This study aimed to identify consistent regions exhibiting structural or functional changes in MTLE and compare the regional distributions of pathology detected by different neuroimaging modalities. To that end, thirty-six coordinate-based meta-analyses were performed by applying Alteration Likelihood Estimation to voxel-based morphometry (VBM) and voxel-based physiology (VBP) studies. The meta-analyses revealed convergent MTLE pathology in the epileptogenic hippocampus, bilateral thalamus (medial dorsal nucleus and pulvinar), and striatum (caudate and putamen); significant findings were partially colocalized between VBM-atrophy and VBP analyses, with VBP effects driven primarily by reports of cerebral hypometabolism. Subgroup meta-analyses of blood-oxygen-level-dependent (BOLD) signal-derived metrics revealed additional regions of functional disturbance but were underpowered, requiring further investigation to establish their potential for revealing novel aspects of MTLE pathophysiology via functional magnetic resonance imaging (fMRI). These findings support the current understanding of MTLE as a network-based pathology with progressive neurodegeneration in the hippocampus and connected regions. This study also highlights promising neuroimaging targets for investigating disease-related alterations and recommends incorporating these regions into functional network models of MTLE. Finally, the present work encourages further exploration of BOLD-derived metrics and specifically urges the epilepsy imaging research community to report amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and regional homogeneity (ReHo) measures for resting-state fMRI studies in standard space coordinates, to advance neuroimaging approaches for improving diagnosis, prognosis, and treatment strategies in MTLE.