Impairments Of Thalamocortical Pathway In Patients With Temporal Lobe Epilepsy: A Diffusion Tensor Imaging Study

Objective: Temporal lobe epilepsy(TLE)is the most common type of focal epilepsy and drug-refractory epilepsy,which has complex structural and functional network abnormalities.The thalamocortical pathway is closely related to information transmission and cognitive function in the brain.This study aims to explore the microstructural changes of the thalamocortical pathway in TLE patients by DTI technology,as well as to probe into the relationship between the structural damage of thalamocortical pathway and cognitive impairment in TLE.Methods: 27 TLE patients and 27 HC patients are enrolled.DTI data,cognitive assessment scale(Mo CA),quality of life in epilepsy scale(QOLIE-31)and other clinical data are collected.According to the cortical function and thalamocortical fiber connectivity,the thalamus is divided into six subregions as regions of interest(ROI),corresponding to motor cortex(MC),sensory cortex(SC),occipital cortex(OC),prefrontal cortex(PFC),posterior parietal cortex(PPC)and temporal cortex(TC).The standard brain atlas is selected to divide the cortex into the above six ROIs according to function.Using the brain functional magnetic resonance imaging software library,the fiber tracking between thalamus and cortical ROIs are performed by using DTI probabilistic fiber tracking technology,and the fractional anisotropy(FA),mean diffusivity(MD),axial diffusivity(AD)and radial diffusivity(RD)of each fiber pathway are calculated.The differences in DTI parameters of the thalamocortical pathway between the two groups are statistically analyzed,and the correlations between DTI parameters of TLE and disease duration,age of onset,and cognitive function scores are analyzed.Results:(1)Compared with the HC group,the AD of the MC pathway increased,the MD of the PFC pathway increases,the FA of the PPC pathway decreases,and the AD,MD and RD increases,the FA of the TC pathway decreases,and the MD and RD increases in the TLE group.(2)The total Mo CA score,visuospatial,abstract,delayed recall scores and the cognitive function scores of the QOLIE-31 in TLE group are significantly lower than those in HC group.(3)The duration of TLE is negatively correlated with the AD of the PPC pathway,and the age of onset is positively correlated with the AD of the PFC and PPC pathway.(4)In the TLE group,the visuospatial score of Mo CA is negatively correlated with FA and AD of the MC pathway and positively correlated with RD of the MC pathway,the naming score is positively correlated with FA and negatively correlated with RD of the TC pathway,the attention score is negatively correlated with AD of the MC and PFC pathway,the abstract score is negatively correlated with MD and AD in the PFC and MD,AD,and RD in the PPC pathway.The total score is negatively correlated with AD of the PFC pathway.Conclusions: This study provides neuroimaging evidence for the view that the thalamus may be an important hub involved in the formation of TLE seizure network,and the temporal lobe,posterior parietal lobe and prefrontal lobe play a major role in this network.The structural damage of the thalamocortical pathway may be the anatomical basis of cognitive impairment and brain functional reorganization in TLE,which may help to carry out targeted interventions for TLE to control or slow down the disease process.