Abstracts

Rationale: Individuals with long-standing Juvenile Myoclonic Epilepsy (JME) have significant atrophy in subcortical regions within the corticostriatal thalamic network. However, the timing and course of these changes are unknown. The aim of the current study was to characterize the progression of subcortical volumetric changes in a group of children with newly diagnosed JME at baseline and after 2 years, compared to typically developing children. Furthermore, we aimed to determine whether baseline subcortical volumes were predictive of performances in executive function 2 years later. Methods: Two sets of T1 weighted SPGR images were obtained, 2 years apart, on a 1.5 Telsa GE Signa scanner in 16 individuals with new and recent onset JME (age = 15.4 2.8 years; epilepsy duration = 8.5 3.7 months) and 42 healthy controls (HC, age = 12.9 3.1 years). Subcortical gray matter structures, including caudate, putamen, pallidum and thalamus, were automatically segmented using FMRIB s Integrated Registration and Segmentation Tool (FIRST), based on T1 image intensity (Patenaude et al., 2011). Analysis of variance was performed, with age and head circumference as a covariate, to compare subcortical volumes between JME and control groups at baseline and after 2 years. To assess if baseline subcortical volumes were predictive of executive function 2 years later, we correlated baseline subcortical volumes with D-KEF verbal fluency scores at 2 years. Results: Subcortical volumes at baseline were similar in JME and controls (all p>0.09, adjusted for head circumference and age). At 2 years after baseline, the JME group showed a modest decline in caudate (p=0.034), pallidum (p=0.049) and thalamus (p=0.021) volumes, compared to controls. The baseline volumes of these subcortical structures in the JME group were significantly linked to better performances on D-KEFS category fluency at 2 years (caudate, rho= 0.5717, p=0.0207; pallidum, rho= 0.638, p =0.0078; thalamus, rho=0.56, p= 0.0219). No such relationship was found in controls. Conclusions: The current study demonstrated that total volumes of subcortical structures within the corticostriatal thalamic network were not significantly altered at or near the onset of JME. However, there is a modest decline in the volume of these structures compared to healthy controls after 2 years, suggesting an evolving neurodevelopmental abnormality in JME. Furthermore, baseline volumes had prognostic significance for later cognitive function as larger baseline subcortical volumes in JME were predictive of better performance in executive function testing after 2 years.