White matter abnormalities in patients with temporal lobe epilepsy and amygdala enlargement: Comparison with hippocampal sclerosis and healthy subjects

Abstract

PurposeCases of temporal lobe epilepsy (TLE) with ipsilateral amygdala enlargement (AE) have increasingly been reported. However, the white matter (WM) abnormalities of TLE patients with AE remain poorly investigated. Here we explored macrostructural and microstructural WM abnormalities in TLE patients with AE compared to normal controls and TLE patients with hippocampal sclerosis (HS). Material and methodsWe selected 17 patients with unilateral TLE with AE (TLE-AE) based on automated amygdala volumetry using FreeSurfer software, and 34 healthy controls and 35 patients with unilateral TLE with HS (TLE-HS) were also recruited. Subsequently, differences in gray matter (GM) and WM volumes and fractional anisotropy (FA) among the three groups were analyzed using SPM8 software. ResultsThe volume analysis of GM obtained results that are consistent with the structural characteristics of TLE with AE and with HS (i.e. amygdala increase in the TLE-AE, and mesial temporal atrophy in the TLE-HS). In the volume of WM, only the TLE-HS patients had WM reductions mainly in the ipsilateral temporal lobe. Compared to the controls, the TLE-AE group showed a significant FA decrease in the ipsilateral anterior cingulum and the corpus callosum, whereas an extended FA decrease in the whole cerebrum was observed in the TLE-HS group. ConclusionOur findings regarding the WM of TLE patients with AE may reflect characteristic pathophysiology such as the anatomical and functional connection between the amygdala and medial prefrontal cortex, and our results may thus provide insights into TLE with AE.