Longitudinal Investigation on the secondary degeneration of nerve fiber tract connecting to the hippocampus after subcortical infarction

Objective ter subcortical infarction and its potential impact on neurological recovery using diffusion tensor imaging(DTI).Methods fifteen consecutive acute patients were recruited within seven days following the onset of stroke.Patients had the unilateral subcortical infarction in the corona radiation of the lateral ventricle and/or centrum ovale without any other signal abnor mality on T 1 and T 2 weighted images.All patients were scanned using MRI of T 1 /T 2 /FLAIR/3D/DTI series at 1weeks,3 and 6 months following a predefined protocol.Thirteen health volunteers(controls) were examined once using the same MRI and DTI protocol during the study period.The mean diffusivity(MD) and fractional anisotropy(FA) in the hippocampus and correlated regions of interest were measured.National Institutes of Health Stroke Scale(NIHSS) and Muntrier Cogni tive Appraisa(MoCA) rating scales were used to evaluate the neurological function before each DTI scan.Results In the time-points of 6 months,FA value had a significant decrease in the unilateral hippocampal body,hippocampus tail,para hippocampal gyrus head,parahippocampal gyrus body,cingule and fornix(P0.05),but MD remained unchanged(P 0.05).NIHSS scores were lower in 3 months than in 1 week,but remained unchanged between 3 and 6 months.The scores of MoCA had been significantly increased over time.Conclusions There are many lesion regions of the nerve fi ber connecting to the hippocampus after the subcortical infarction,which indicates the secondary nerve fiber degenera tion following subcortical infarction.In addition,the secondary nerve fiber degeneration can affect the memory function of the hippocampus,causing the memory disorders after the infarction.