Magnetic Source Imaging And Brain Network Analysis In Childhood Absence Epilepsy Based On Magnetoencephalography

Objective: Childhood absence epilepsy(CAE)is a type of generalized epilepsy with short-lived loss of consciousness.Frequent seizures in the CAE patients can cause reduced attentions and recognitions,which may influence seriously patients? normal life and growing development.To better understand the pathological mechanism of epileptic seizures of CAE and provide help for clinical diagnosis and treatment,it is necessary to give an insight into the brain network characteristics of CAE patients.Methods: Magnetoencephalography(MEG)data were recorded in a no task,eyes-closed and staying awake condition from 15 CAE patients and 15 age-and sex matched healthy children,in Nanjing brain hospital affiliated to Nanjing medical university.For each subject,the brain-network spectral power,functional connectivity and network metrics,including clustering coefficient,characteristic path length and small-worldness,were computed in the theta band and sensor space.Statistical differences in the brain-network features between the CAE and healthy control groups were tested with a non-parametric statistic,the Wilcoxon rank-sum test.Bonferroni correction was used to control the false positive discover rate for multiple comparisons.Results: Our results show that the CAE group has significantly increased spectral power in the theta band compared with the healthy group(p = 0.0011).The stronger power in the CAE group mainly distributes in right hemisphere,i.e.in the right occipital,parietal and temporal regions,while the stronger power in the healthy group displays a bilaterally symmetrical distribution,focusing on the bilateral occipital,parietal and temporal regions.Compared with the healthy group,the CAE group exhibits a significantly increased global mean functional connectivity in the theta band(p = 0.00031).With respect to regional mean functional connectivity,the CAE group relative to the healthy group displays significantly increased connectivity in the right local parietal(p = 0.033),parieto-central(p = 0.011)and centro-frontal(p =0.033)regions.Statistically significant differences were found in network topological metrics between the CAE and healthy groups in the theta band.Compared with the healthy group,the CAE group has significantly increased clustering coefficient(p =0.01),characteristic path length(p = 0.024)and reduced small-world attribution(p =0.013).Conclusion: Compared with the healthy group,the CAE group shows significantly abnormal changes in the spectral power,functional connectivity and graph theory metrics in the theta band.The increased spectral power in the theta band means that the brain dominant rhythm of CAE patients is the theta rhythm in the resting-state and eyes-closed condition.The increased functional connectivity means a hypersynchrony in functional connectivity between the brain regions of CAE patients,which may cause abnormal discharges.Finally,our results show the brain network of CAE patients reorganizes towards a more regular topological architecture.Our findings are helpful for studying the pathological mechanism of CAE,determining seizure types and making treatment plans.