Quantification of thalamic nuclei in patients diagnosed with temporal lobe epilepsy and hippocampal sclerosis

Purpose The aim of this study is to investigate the changes in the volume of individual thalamic nuclei in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). Methods We enrolled 80 TLE patients with HS and 40 healthy controls. All of the subjects underwent 3D T1-weighted imaging. The hippocampus subfields and thalamic nuclei were segmented using the FreeSurfer program. We investigated volume changes in thalamic nuclei according to the HS side involved, and types or antiepileptic drug (AED) response compared with healthy controls. Results Compared with healthy controls, patients with HS showed atrophy of thalamic nuclei involving right and left parafascicular nuclei. In the right HS, the atrophy of the right thalamic nucleus was more prominent than that of the left thalamic nucleus, whereas the reduction in the volume of left thalamic nuclei was more prominent in patients with left HS. The reduction in thalamic nuclear volumes was more prominent in HS type 1 (atrophy of both CA1 and CA4 regions) than in other HS types. The suprageniculate nuclear volumes were significantly increased in patients with drug-controlled epilepsy. Conclusions Our study demonstrates thalamic nuclear atrophy in TLE patients with HS. In addition, the atrophy of individual thalamic nuclei varied according to the HS side, the HS types, and the AED response. These findings suggest that the role of thalamic nuclei varied in TLE with HS subtypes and displayed varying degrees of vulnerability in the pathology networks associated with the hippocampus.