| Backgrounds: Currently,more than one-third of drug-resistant temporal lobe epilepsy(DTLE)patients continued to develop seizures after resection surgery.Dynamic functional network connectivity(DFNC)analysis,capturing temporal properties of dynamic functional connectivity during rs-f MRI(resting state functional Magnetic Resonance Imaging)acquisition,may help us to identify unfavorable surgical outcomes,and it may be a suitable method to detect cognitive changes in DTLE.Purposes: To study the differences in DFNC and temporal variations between DTLE patients and healthy controls(HC),and seizure-free(SF)patients,not seizure-free patients(NSF)and HC.To explore the correlation between connection strength of DFNC and temporal variations(fractional windows,mean dwell time and number of transitions)and surgical outcome,cognitive function and clinical variables in DTLE patients.Methods: First,we evaluated 61 DTLE patients matched for age and gender with 51 HC.DTLE patients were classified with seizure-free(n =39)and not seizure-free(n = 16)based on the Engel surgical outcome scale.Six patients were unable to confirm the postoperative status and were not included in subgroups analysis.Then,66 DTLE patients and 31 HC matched for age,sex and education were evaluated,calculated DFNC in the whole brain resting state network(RSN),focusing on the correlation between cognitive impairment and DFNC as well as temporal variations Besides,DFNC and the correlation of temporal characteristics with clinical variables in TLE patients were also investigated.The DFNC was calculated using group spatial independent component analysis and sliding window approach.Results:(1)In the course of the study of the surgical outcome,the DFNC analysis suggested two distinct connectivity ‘States’ : State II appearing much more frequently than State I(74.83% versus 25.17%).(2)DTLE subgroups analysis showed not seizure-free(NSF)patients had a prolonged overall frequency(HC: 69.31%;SF: 69.44%;NSF: 91.45%)and spent significantly more time(HC: 247.40;SF: 294.60;NSF: 558.50)in State II,compared to seizure-free(SF)patients and HC.Further,number of transitions from State II to State I was showed a significantly lower in NSF patients(HC: 4.90;SF: 4.87;NSF: 2.00).(3)SF patients had compensatory enhancement of DFNC strengths between default and dorsal attention network,as well as within the default network.While reduced DFNC strengths of within-network and inter-network were both observed in NSF patients(P<0.05,FDR-corrected).(4)In the study of cognitive function and clinical variables,the DFNC results show four different dynamic functional connectivity states,among which State 1(21.6%)and State 2(57.2%)appear more frequently,State 3(12.7%)and State 4(8.5%)appear less frequently.While DTLE patients have weaker intra-network and inter-network functional connectivity than HC,the patient group stayed longer(HC:115.7;DTLE:209.9)in State 2 and had fewer transitions(HC:10.10;DTLE:7.71)between states.(5)DTLE patients had extensive cognitive impairment,and that altered DFNC is strongly associated with the severity of cognitive impairment and clinical variables(P < 0.05).Conclusions: Our study indicates that DFNC could offer a better understanding of dynamic neural impairment mechanisms of drug-resistant TLE functional network,epileptic brain network reorganization and provide the additional preoperative evaluation support for surgical treatment of drug-resistant TLE.The DFNC research approach can assess the temporal variations of the resting state based on studies of functional connectivity,which may reflect the more comprehensive functional capabilities of the central nervous system,may be a useful brain neuroimaging-based biomarker to characterize cognitive dysfunction and disease severity in DTLE,and may provide a new direction for future studies of other types of neuropsychiatric disorders. |
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