Brain morphology in juvenile myoclonic epilepsy and absence seizures

Objective We evaluated the differences in brain morphology among patients with juvenile myoclonic epilepsy according to the occurrence of absence seizures. Materials and methods Twenty-one juvenile myoclonic epilepsy patients with (n = 6) and without (n = 15) absence seizures were enrolled. We analyzed whole-brain T1-weighted magnetic resonance imaging using FreeSurfer 5.1. Measures of cortical morphology, such as thickness, surface area, volume, and curvature, and the volumes of subcortical structures, the cerebellum, and cerebrum, were compared between the groups. Moreover, we quantified correlations between clinical variables and each measures of abnormal brain morphology. Results Compared to normal controls, patients without absence seizures demonstrated thinning of the cortical thickness in the right hemisphere, including the post-central, lingual, orbitofrontal, and lateral occipital cortex. Compared to normal controls, patients with absence seizures had more widespread thinning of the cortical thickness, including the right post-central, lingual, orbitofrontal, and lateral occipital cortexes as well as the right inferior temporal cortex. Additionally, the volume of cerebellar white matter in patients without absence seizures was significantly smaller than that in normal controls. Patients with absence seizures had a much smaller cerebellar white matter volume than normal controls or patients without absence seizures. Moreover, there was significantly positive correlation between the age of seizure onset and the volume of cerebellar white matter in patients with juvenile myoclonic epilepsy. Conclusions We demonstrated that there were significant brain morphology differences in patients with juvenile myoclonic epilepsy according to the presence of absence seizures. These findings support the hypothesis that juvenile myoclonic epilepsy may be a heterogeneous syndrome.