Alternations in static and dynamic functional connectivity density in temporal lobe epilepsy with and without...

To comprehensively examine static and dynamic functional connectivity density (FCD) in temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) and MRI-negative TLE and its potential correlation with cognition.

Fifty-three healthy controls (HC), 38 TLE-HS patients, and 51 MRI-negative TLE patients underwent MRI scans of resting-state BOLD functional imaging and 3D T1WI sequence. Static functional connectivity density (FCD) and corresponding temporal dynamic FCD (dFCD) were calculated utilizing a sliding window approach and statistically compared among groups. Further seed-based functional connectivity (FC) analysis and ROC curve analysis were executed. Relationships between cognitive scores and FCD or dFCD values were analyzed by Spearman correlation.

The TLE-HS and MRI-negative TLE both demonstrated reduced static FCD values in the temporal neocortex ipsilateral to the epileptogenic focus. However, the TLE-HS revealed larger aberrant cluster sizes of reduced FC in the ipsilateral frontal and temporal lobes. For dFCD, its elevation in the ipsilateral temporal neocortex was detected only in MRI-negative TLE. The dFCD was significantly correlated with cognitive scores and revealed a moderate discrimination ability.

The combination of static FCD and dFCD could provide novel and complementary evidence to help deepen our understanding of the whole brain function's impairment and compensatory mechanism in TLE. The patterns of change in FCD abnormalities were similar between TLE-HS and MRI-negative TLE, which were more pronounced and widely involved in the TLE-HS group. Furthermore, dFCD may reveal more nuanced variations in MRI-negative TLE and help in discrimination.