Objective To investigate the changes in brain dynamic functional connectivity (dFC) in children and adolescents with idiopathic generalized epilepsy (IGE) who have negative findings for conventional magnetic resonance imaging (MRI) and to explore the correlation between dFC indicators and clinical variables.

Methods A total of 40 children and adolescents with IGE who have negative findings for routine brain MRI and 37 healthy controls were enrolled. T₂-fluid attenuated inversion recovery (T₂-FLAIR) was performed for all subjects. They also uinderwent 3-dimensional T₁ weighted imaging (3D-T₁WI) and resting-state functional MRI (rs-fMRI). Using independent component analysis (ICA), sliding time windows, and k-means clustering, we identified 6 functional connectivity states and derived dFC indicators, including fraction of time, mean dwell time, and the number of transitions. Then, SPSS18.0 and GIFT software Stats module were used to analyze the intergroup differences in dFC and its correlation with clinical variables. The reliability and stability of the dFC results were validated by changing the size of the sliding window.

Results There were no significant differences in the general clinical data between the IGE group and the control group (P>0.05). Compared with the control group, the IGE group showed in state 5 increased dFC within the default mode network (DMN), increased dFC between DMN and the frontoparietal network (FPN), and decreased dFC between DMN and the visual network (VN) (P<0.001). In state 6, the IGE group showed increased dFC between DMN and VN, increased dFC between the basal ganglia network (BGN) and the sensorimotor network (SMN), decreased dFC between the DMN and the attention network (ATTN), and decreased dFC within the VN (P<0.001). There were statistically significant differences between the two groups in the fraction of time (Z=－2.192, P=0.028) and the mean dwell time (Z=－2.144, P=0.032) in state 1, in the fraction of time (Z=－2.444, P=0.015) and the mean dwell time (Z=－2.368, P=0.018) in state 4, and in the fraction of time (Z=－2.047, P=0.041) in state 6. There was a negative correlation between the duration of the disease and the fraction of time of state 1 in the IGE group (r=－0.421, P=0.007, Bonferroni correction). In the validation analysis, significant differences in dFC indicators between the IGE group and the control group persisted when the size of the sliding window and the number of clusters were changed.

Conclusion Children and adolescents with IGE and negative findings for conventional MRI exhibit abnormal dynamic properties of whole-brain functional connectivity, and the fraction of time of state 1 in IGE patients is correlated with clinical variables, providing new imaging evidence for research in the neural mechanisms of children and adolescents with IGE.