Abstracts

Rationale: The role of the thalamus is of great interest in epilepsy research. The thalamus maintains extensive anatomic interconnectivity with other brain structures that are known to play an important role in seizure initiation, modulation, and propagation. In addition, the thalamus is known to play a significant role in both memory and non-memory cognitive domains. Several neuroimaging studies have reported thalamic atrophy in adult epilepsy patients, primarily those with temporal lobe epilepsy. Recent studies have also reported thalamic abnormalities in children with either generalized seizures or TLE, but these have typically included children with several years of epilepsy duration. The current study investigated thalamic integrity in a group of children and adolescents with new-onset epilepsy.Methods: 51 control subjects (mean age = 13.3 years) and 59 subjects diagnosed with epilepsy (mean age = 12.9 years) were included in this study. All epilepsy subjects were investigated within one year of epilepsy onset. All subjects underwent quantitative magnetic resonance imaging, including manual tracing of the thalamus according to published guidelines. Differences in thalamic volumes (corrected for intracranial volume) between controls and TLE patients were assessed. Secondary analyses examined differences in thalamic volumes between controls, children diagnosed with localization-related epilepsy (n = 31) and idiopathic generalized epilepsy (n=28). Finally, correlations were conducted to assess for relationships between thalamic volumes and clinical seizure variables.Results: Children with new onset epilepsy showed a significant reduction in thalamic volume compared to controls (p = .02). This was evident on a bilateral basis. The thalamic volumes of subjects with localized TLE and generalized TLE were significantly reduced compared to controls, but were not significantly different from each other. No significant correlations between thalamic volumes and clinical seizure variables (e.g., age of onset) were observed.Conclusions: These results indicate that thalamic atrophy is evident very early in the course of temporal lobe epilepsy. Future work will examine the changes in thalamic integrity over time in these children and its relationship to clinical course.