Reduction of ipsilateral thalamic volume in temporal lobe epilepsy with hippocampal sclerosis.

The thalamus plays an important role in the modulation of both focal and generalized seizures, but the mechanisms related to seizures may be different among epilepsy syndromes. The aim of this study is to investigate the thalamic atrophy in different epilepsy syndromes. We enrolled a total of 72 patients with epilepsy (22 patients with temporal lobe epilepsy with hippocampal sclerosis, 21 patients with extra-temporal lobe epilepsy, and 29 patients with juvenile myoclonic epilepsy). We analyzed structural volumes of the brain with FreeSurfer 5.1 software, and compared them among subgroups of epilepsy and normal control subjects. Moreover, we quantified correlations between the duration of epilepsy and the structural volumes with age and sex as covariates. The volumes of the ipsilateral hippocampus in temporal lobe epilepsy with hippocampal sclerosis were significantly smaller than those in extra-temporal lobe epilepsy and normal control subjects [analysis of variance (ANOVA), p < 0.001]. Although the volumes of the ipsilateral thalamus were not different from those of normal control subjects, the volumes of the ipsilateral thalamus were negatively correlated with duration of epilepsy in temporal lobe epilepsy with hippocampal sclerosis (r = -0.5, p = 0.02). However, the volumes of interest in extra-temporal lobe epilepsy and juvenile myoclonic epilepsy were not different from those in normal control subjects, and none of these structures were correlated with duration of epilepsy. These findings suggest that the role of the thalamus may be different in thalamo-limbic circuits among epilepsy syndromes.

Juvenile myoclonic epilepsy may be a disorder of cortex rather than thalamus: An effective connectivity analysis.

Although juvenile myoclonic epilepsy has been considered as a disorder of thalamo-cortical circuit, it is not determined the causality relationship between thalamus and cortex. The aim of this study was to evaluate whether juvenile myoclonic epilepsy is a disorder of thalamus or cortex. Twenty-nine patients with juvenile myoclonic epilepsy and 20 normal controls were enrolled in this study. In addition, we included 10 patients with childhood absence epilepsy as a disease control group. Using whole-brain T1-weighted MRIs, we analyzed the volumes of the structures, including hippocampus, thalamus, and total cortex, with FreeSurfer 5.1. We also investigated the effective connectivity among these structures using SPSS Amos 21 based on these volumetric measures. The structural volumes in juvenile myoclonic epilepsy were not different from those in normal controls. There was a statistically significant effective connectivity from the total cortex to the thalamus in the patients with juvenile myoclonic epilepsy. In addition, a significant effective connectivity from the hippocampus to the ipsilateral thalamus was revealed. Unlike the patients with juvenile myoclonic epilepsy, neither the patients with childhood absence epilepsy nor normal controls had a significant effective connectivity from the total cortex to the thalamus or from the thalamus to the cortex. The connectivity of brain in patients with juvenile myoclonic epilepsy could be different from that in patients with childhood absence epilepsy, and the cortex rather than the thalamus might play a critical role in the pathogenesis of juvenile myoclonic epilepsy.

Cerebellar white matter changes in patients with newly diagnosed partial epilepsy of unknown etiology.

OBJECTIVE: We hypothesize that pre-existing susceptible structures in the brain may be associated with the development of newly diagnosed partial epilepsy of unknown etiology. METHODS: Twenty-two patients with newly diagnosed partial epilepsy of unknown etiology and 36 healthy controls were enrolled in this study. In addition, we included 24 patients with chronic partial epilepsy of unknown etiology as a disease control group. We analyzed whole-brain T1-weighted MRIs using FreeSurfer 5.1. The volumes of the hippocampus, amygdala, thalamus, caudate, putamen, pallidum, brainstem, cerebellar gray and white matter, as well as cerebral gray and white matter were compared between the groups. We also analyzed the changes in brain volumes associated with the chronicity of epilepsy in the patients with chronic epilepsy compared to newly diagnosed epilepsy. RESULTS: The volume of cerebellar white matter in patients with newly diagnosed epilepsy was significantly smaller than that which was observed in the healthy controls (p=0.0001). This finding was also observed in patients with chronic epilepsy (p<0.0001). Cerebral white matter volume was negatively correlated with the duration of epilepsy (r=-0.4, p=0.04). CONCLUSION: These findings support our hypothesis that cerebellar white matter changes may constitute a pre-existing susceptible structure in the brain that is associated with the development of partial epilepsy of unknown etiology. In addition, cerebral white matter was the structure that was the most vulnerable to the progression of epilepsy.