Demystifying cognitive impairment in non-lesional temporal lobe epilepsy: role of diffusion tensor imaging in correlation with neuroinflammatory biomarkers

Abstract Background Cognitive impairment (CI) is a major complication of temporal lobe epilepsy (TLE). The precise mechanism of CI in epilepsy is not well understood, even though there is an increased understanding about contribution of neuroinflammatory mechanisms with resultant neural network disruption. The aim of this study was to evaluate the utility of diffusion tensor imaging (DTI) in early detection of microstructural white matter (WM) tracts abnormalities in TLE, explore their contribution to CI and their correlation with neuroinflammatory biomarkers. Results This study included 200 subjects classified into 2 groups: 100 patients with TLE and 100 matched healthy controls. All participants underwent a full neurological assessment, cognitive function evaluation using Mini-Mental State Examination (MMSE), measurement of serum levels of High Mobility Group Box-1 (HMGB1) and S100 calcium-binding protein B (S100B). DTI was performed with measurement of fractional anisotropy (FA) and mean diffusivity (MD) values of WM tracts. There was a statistically significant negative correlation between MMSE score and serum levels of HMGB1 ( r = − 0.916) as well as S100B ( r = − 0.910), ( P = 0.001). As regard DTI of the examined WM tracts, TLE group had significantly lower FA and higher MD values than the control group. This study showed a statistically significant positive correlation between MMSE score and FA as well as negative correlation between MMSE score and MD values of uncinate fasciculus (UF), arcuate fasciculus (AF) and parahippocampal (PH) fibers bilaterally. HMGB1 and S100B levels were negatively correlated with the FA values and positively correlated with the MD values of the UF, AF and PH fibers bilaterally. Conclusions DTI has emerged as a sensitive technique for early detection of WM microstructural changes in TLE and their contribution to CI that were correlated with neuroinflammatory biomarkers. It can serve as an imaging prognostic marker in TLE patients, highlighting the disease-related complications on the long run.