Impaired Default Mode Network In Different Epilepsy Types:a Resting-state Functional MRI Study

Purpose:Impaired consciousness has long been considered the hallmark of different epilepsy types. And the impaired consciousness was thoutht to be associated with default mode network (DMN). The purpose of the present study was to evaluate the relationship between the alteration of the DMN and the level of consciousness in four epilepsy types in the resting-state using the functional magnetic resonance imaging (fMRI).Materials and methods:One hundred and seventy-four epilepsy patients were included in the present study. And they were devided into four patient groups, including35simple partial seizure (SPS) epilepsy patients,47complex partial seizure (CPS) epilepsy patients,51partial secondary generalized tonic-clonic seizure (SGTCS) epilepsy patients,41idiopathic generalized tonic-clonic seizure (IGTCS) patients. Fifty healthy people were set as control group. The fMRI data of all subjects were obtained on a SIEMENS MAGNETOM Trio3T scanner. The DMN of all subjects were extracted by using independent component analysis and a DMN template-matching component selection approach. First, we compared the functional connectivity between each patient group and the healthy control group using two sample T test (P<0.05). Then one-way analysis of variance (ANVOA) was adoptted to investigate the impairment of DMN in each patient group (P<0.05). In addition, the correlation between the impaired DMN and both the epilepsy duration and seizure frequency of each patient group was also observed (P<0.05).Results:Increased functional connectivity in posterior part of DMN [posterior cingulate cortex (PCC)/precuneus (PCUN)] and decreased functional connectivity in anterior part [mesial prefrontal cortex (MPFC) and bilateral temporal lobe] occurred in all epilepsy groups compared to controls. One-way ANOVA showed that functional integrations of DMN in partial seizure patients were lower than the GTCS patients. The concordance of spontaneous activity within DMN increased ranging from SPS, CPS to IGTCS, SGTCS, and then control group. In GTCS patients, we discovered that the functional connectivity of anterior part (MPFC) in DMN was negtively correlated with the both seizure frequency and epilepsy duration (P<0.05). And also, the positive correlation was found between the functional connectivity of posterior part (PCC/PCUN) in DMN and both frequency and epilepsy duration (P<0.05).Conlusion:Increased functional connectivity in posterior part and decreased in anterior part within DMN in all epilepsy types was associated with loss of consciousness in epilepsy patients. And the degree of impaired consciouness was negatively correlated with the integrations of DMN, which may be assist to clinicians in the disgnosis of epilepsy type and assess the degree of impaired consciousness in epilepsy patients.