Disrupted Coupling Between the Spontaneous Fluctuation and Functional Connectivity in Idiopathic Generalized Epilepsy.

Xiaoyan Jia,Sisi Jiang,Qiong Zhu,Dezhong Yao,Shuai Ma,Liang Yu,Honbin Sun,Xuebin Chang,Debo Dong,Cheng Luo

doi:10.3389/fneur.2018.00838

Abstract

Purpose: The purpose of this study was to comprehensively evaluate alterations of resting-state spontaneous brain activity in patients with idiopathic generalized epilepsy (IGE) and its subgroups [juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures (GTCS)].Methods: Resting state functional magnetic resonance imaging (fMRI) data were acquired from 60 patients with IGE and 60 healthy controls (HCs). Amplitude of low frequency fluctuation (ALFF), global functional connectivity density (gFCD), local FCD (lFCD), and long range FCD (lrFCD) were used to evaluate spontaneous brain activity in the whole brain. Moreover, the coupling between ALFF and FCDs (gFCD, lFCD, and lrFCD) was analyzed on both voxel-wise and subject-wise levels. Two-sample t-tests were used to analyze the difference in ALFF, FCDs and coupling on a subject-wise level between the two groups. Nonparametric permutation tests were used to evaluate differences in coupling on a voxel-wise level.Key findings: Patients with IGE and its subgroups showed reduced ALFF, gFCD and lrFCD in posterior regions of the default mode network (DMN). In addition, decreased ALFF and increased coupling with FCD were found in the cerebellum, while decreased coupling was observed in the bilateral pre- and postcentral gyrus in IGE compared with the coupling in HCs. Similar findings were found in the analysis between each of the two subgroups of IGE (JME and GTCS) and HCs, and JME patients had increased coupling in the cerebellum and bilateral middle occipital gyrus compared with coupling in the GTCS patients.Significance: This study demonstrated a multifactor abnormality of the DMN in IGE and emphasized that the abnormality in the cerebellum was associated with dysfunctional motor symptoms during seizures and might participate in the regulation of GSWDs in IGE.

Highlights

Idiopathic generalized epilepsy (IGE) is characterized by widespread generalized epileptic discharges, including generalized tonic-clonic, absence, and myoclonic seizures [1]
The significantly increased long range FCD (lrFCD) were located in the left posterior temporal lobe and right middle and inferior temporal gyrus and the significantly decreased lrFCD were found in the right inferolateral remainder of parietal lobe, left cingulate gyrus of posterior part and right superior frontal gyrus
Patients with IGE, including generalized tonic-clonic seizures (GTCS) and Juvenile myoclonic epilepsy (JME), showed reduced Amplitude of low frequency fluctuation (ALFF) in cerebellum and regions in the default mode network (DMN) and increased ALFF in the frontal regions related to motor function

Summary

Introduction

Idiopathic generalized epilepsy (IGE) is characterized by widespread generalized epileptic discharges, including generalized tonic-clonic, absence, and myoclonic seizures [1]. Using scalp electroencephalography (EEG), generalized spike-andwave discharges (GSWDs) at 2.5–5 Hz are observed in GTCS. JME is characterized clinically by myoclonic jerks after awakening, tonic-clonic seizures, and an EEG with 3–4 Hz poly-spikes and GSWDs with fronto-central predominance [3]. Non-invasive neuroimaging techniques such as functional magnetic resonance imaging (fMRI) provided helpful tools to uncover the potential mechanisms of IGE [7,8,9]. Some researchers have proposed that the coupling of fMRI features would provide a complementary strategy to evaluate the state of the human brain [11]. We analyzed the brain dysfunction associated with IGE and its subgroups using a coupling of fMRI features

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