Default Mode Network In Childhood Absence Epilepsy By 3.0T MRI

Background: Childhood absence epilepsy(CAE) is a more common type of age-dependent idiopathic generalized epilepsy(IGE), frequently absence seizure every day as the only neurological symptoms, without metabolic or other neurological disorders. It has a representative EEG characteristic, namely 3Hz spike-wave discharges. As a result, more and more researchers focus on CAE. In recent years, resting state functional magnetic resonance imaging(fMRI) becomes more and more mature and has been applied to explore the pathogenesis of CAE, furthermore, some studies have found that the default-mode network(DMN) may correlate with consciousness and cognitive function. However, it is insufficient to consider that CAE patients’ default-mode network is abnormal, so more evidences are needed to support.Objective: To explore the default mode network(DMN) in childhood absence epilepsy(CAE) patients and examine their correlations between functional connectivity(FC) and clinical characteristics.Methods: Fourteen CAE patients and fourteen healthy volunteers were prospectively recruited from September 2012 to June 2014. FC in DMN of each group, between-group comparison of DMN FC and their relationships with clinical characteristics were respectively analyzed using 3.0T resting-state functional magnetic resonance imaging FC analysis seeding at bilateral precuneus/posterior cingulate cortex(PCC).Results: Seeding at the bilateral precuneus/posterior cingulate cortex(PCC), positive connection was found in bilateral angular gyrus, bilateral superior parietal gyrus, bilateral superior and middle frontal gyrus, bilateral superior medial frontal gyrus,bilateral middle temporal gyrus, bilateral superior and middle occipital gyrusin controls. However, positive connection in CAE patients was observed in bilateral superior parietal gyrus and bilateral superior occipital gyrus. Between-group analysis of DMN connectivity revealed a reduction of DMN FC in the bilateral medial orbitofrontal cortex [coordinate(x, y, z):3,60,-9,t=-5.24,P<0.01], left superior frontal gyrus/middle frontal gyrus [coordinate(x, y, z):-24,24,48,t=-5.21,P<0.01], right superior superior frontal gyrus/middle frontal gyrus [coordinate(x, y, z):18,30,45,t=-4.14,P<0.01], left anterior cingulate cortex/caudate [coordinate(x, y, z):-3,15,-6,t=-7.59,P<0.01] and right anterior cingulate cortex [coordinate(x, y, z):9,48,15,t=-7.59,P<0.01] in CAE patients. Moreover, increased DMN FC was present in right paracentral lobule and right middle cingulate gyrus [coordinate(x, y, z):12,-36,54,t=6.19,P<0.01]. FC between PCC and the bilateral medial orbitofrontal cortex or bilateral superior/middle frontal gyrus correlated negatively with disease duration(r=-0.544,-0.534,-0.790,P<0.05), but there was no correlation with seizure frequency or initial age.Conclusions: Brain’s default mode work in childhood absence epilepsy is impaired, presumably, as a result of unconsciousness and cognitive impairment during absence seizure. Abnormal DMN activities may be a biomarker of disease progress in absence epilepsy.