Relationship between environmental factors and gray matter atrophy in refractory MTLE

Abstract

Objective: To investigate clinical, neuropsychological, and MRI abnormalities (gray matter atrophy [GMA] and white matter atrophy [WMA]) in surgical mesial temporal lobe epilepsy (MTLE) patients with and without familial antecedent for epilepsy. Methods: A cohort study including 69 operated patients with unilateral MTLE, divided into a group of 29 patients (mean age 35.8 ± 10.4 years) with a negative family history (FH) of epilepsy and a group of 40 patients (32.8 ± 10 years) with a positive FH. We performed voxel-based morphometry (VBM) on preoperative MRIs and investigated possible clinical and neuropsychological differences between the 2 groups. We also performed VBM and t tests to compare the patients' groups with normal controls. Results: The negative-FH group had lower IQ scores (p = 0.004), performed poorer on the Boston Naming Test (p = 0.02) and on delayed recall (p = 0.03), and presented a more prominent asymmetry index of hippocampal volume (p = 0.04) and more frequent initial precipitating injuries (p = 0.023). VBM showed a more restricted pattern of GMA in the positive-FH group and a more bilateral and widespread pattern of GMA in the negative-FH group, involving thalami, temporal, frontal, parietal, and occipital lobes. WMA was widespread and bilateral in both groups. Conclusions: The more widespread structural voxel-based morphometry abnormalities and worse IQ performance identified in the negative–family history (FH) group may result from a stronger environmental influence, including initial precipitating injuries. This is further support for the hypothesis that hippocampal sclerosis in mesial temporal lobe epilepsy with positive FH is determined by a stronger genetic predisposition with less influence of environmental factors compared with patients in the negative-FH group.