Structural and functional connectivity in newly diagnosed juvenile myoclonic epilepsy

Abstract

Objectives: We aimed to evaluate structural and functional connectivity of patients with newly diagnosed juvenile myoclonic epilepsy (JME) compared to healthy subjects.

Methods: We enrolled 36 patients with a diagnosis of JME, who were newly diagnosed and drug-naïve. They underwent T1-weighted imaging, and structural volumes were calculated using FreeSurfer software. In addition, EEG data were obtained from all of them. Structural and functional connectivity matrices were estimated by calculating the structural volumes and EEG amplitude correlation, respectively. Then, the connectivity measures were calculated using the BRAPH program. We also enrolled healthy subjects to compare its structural and functional connectivity with the patients with JME.

Results: We observed that patients with JME exhibited significantly different functional and structural connectivity compared to healthy control subjects. In the global structural connectivity, global efficiency, and local efficiency, and small-worldness index were decreased, whereas characteristic path length was increased in patients with JME. Betweenness centrality of cingulate, precentral, superior parietal, and superior frontal cortex was increased in patients with JME whereas that of hippocampus was decreased. In the functional connectivity, the betweenness centrality of the fronto-central electrodes was significantly increased.

Conclusions: This study reports that the structural connectivity and functional connectivity in patients with JME are significantly different from those in healthy control subjects, even those with newly diagnosed drug-naive state. The patients with JME exhibited disrupted topological disorganization of the global brain network and hub reorganization in structural and functional connectivity. These alterations are implicated in the pathogenesis of JME and suggestive of network disease.

Keywords: brain; electroencephalography; juvenile myoclonic epilepsy; magnetic resonance imaging.