Summary Purpose:  Thalamofrontal abnormalities have been identified in chronic primary generalized epilepsy, specifically in juvenile myoclonic epilepsy (JME). These regions also underlie executive functioning, although their relationship has yet to be examined in JME. This study examined the relationship between thalamic and frontal volumes and executive function in recent‐onset JME compared to healthy control subjects and recent‐onset benign childhood epilepsy with centrotemporal spikes (BCECTS), a syndrome not typically associated with thalamocortical or executive dysfunction. Methods:  Twenty children with recent‐onset JME were compared to 51 healthy controls and 12 children with BCECTS using quantitative magnetic resonance imaging (MRI) and measures of executive abilities. Quantitative thalamic and frontal volumes were obtained through semi‐automated software. Subtests from the Delis–Kaplan Executive Function System (D‐KEFS) and the Behavior Rating Inventory of Executive Function (BRIEF) were used to measure executive function. Results:  Executive functions were impaired in JME subjects compared to control and BCECTS subjects. Subjects with JME had significantly smaller thalamic volumes and more frontal cerebrospinal fluid (CSF) than control and BCECTS subjects. Thalamic and frontal volumes were significantly related to executive functioning in the JME group, but not in the other two groups. Discussion:  Children with JME have significant executive dysfunction associated with significantly smaller thalami and more frontal CSF. Children with recent‐onset BCECTS do not display the same pattern. Frontal and thalamic volumes appear to mediate the relationship between executive functioning and brain structure in JME.

Few studies have examined the relative degree of brain volume loss in both the hippocampi and subcortical structures in unilateral temporal lobe epilepsy (TLE), and their association with clinical seizure correlates. In this study, quantitative MRI volumes were measured in the hippocampus, thalamus, caudate, putamen, and corpus callosum in 48 unilateral TLE patients (26 rights, and 22 lefts) and compared to 29 healthy controls. The ipsilateral hippocampus, corpus callosum, and bilateral thalami showed the greatest volume loss, reflected by large to moderate effect size differences compared to controls. Bilaterally, the putamen showed the next highest volume reduction. The contralateral hippocampus and bilateral caudate nuclei showed the least volume reduction, characterized by small effect sizes. Furthermore, clinical seizure characteristics (e.g, duration of epilepsy) showed different patterns of association with the volume reductions observed across these structures. Findings suggest that distinct neurodevelopmental features may play a role in the volume abnormality observed in these regions.

This study examined quantitative magnetic resonance volumes of the thalamus and hippocampus and determined their relationship with cognitive function and clinical seizure characteristics in a sample of 46 unilateral temporal lobe epilepsy (TLE) subjects (20 left and 26 right) and 29 controls. The hippocampus and thalamus exhibited different patterns of volume abnormality, different associations with clinical seizure characteristics, and different patterns of relationship with cognitive measures. Hippocampal volume reduction was primarily ipsilateral to the seizure focus, and thalamic volume reduction was bilateral. Ipsilateral hippocampal volume was significantly correlated with both early neurodevelopmental features (age of seizure onset) and disease characteristics (duration of epilepsy), whereas thalamus integrity was related only to disease variables. Hippocampal volume showed a selective association with verbal memory performance. In contrast, both left and right thalamic volumes were significantly correlated with performance on both memory and nonmemory cognitive domains. These findings underscore the importance of thalamic atrophy in chronic TLE and its potential implications for cognition. (JINS, 2008, 14, 384-393.)

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