Levodopa Responsiveness In PIGD Subtype Parkinson’s Disease Patients And White Matter Alterations In Diffusion Tensor Imaging

Objectives: To investigate the relationship between levodopa responsiveness and white matter(WM)alterations in postural instability and gait disorder(PIGD)subtype Parkinson’s disease(PD)patients using diffusion tensor imaging(DTI)-based tract-based spatial statistics(TBSS).Methods: PIGD subtype PD patients admitted to The Second Affiliated Hospital of Chongqing Medical University during January,2017 to December,2019 were recruited and evaluated using Mini-Mental State Examination(MMSE),Hoehn and Yahr scale(H&Y)and Unified Parkinson’s Disease Rating Scale(UPDRS).DTI scan and routine magnetic resonance imaging(MRI)scan with high-resolution sagittal T1 imaging were performed.Each patient accepted acute levodopa challenge test within 48 hours after MRI scan.Improvement rate of UPDRS-III was calculated.PD patients were grouped into responsive group(Improvement rate≥30%)and irresponsive group(Improvement rate<30%).TBSS analysis was used to identify the difference area of fractional anisotropy(FA),mean diffusivity(MD),axial diffusivity(AD),and radial diffusivity(RD).Results: Twenty-six PIGD subtype PD patients were included(15patients in responsive group and 11 patients in irresponsive group).There was no difference in age,sex,MMSE,H&Y stage,and baseline UPDRS-III score between the two groups.UPDRS-III score after challenge was higher in irresponsive group compared to responsive group.Compared to responsive group,patients in irresponsive group had decreased FA in splenium/body/genu of corpus callosum,bilateral cingulum,left anterior,posterior and superior corona radiata,left anterior,posterior limb of internal capsule,left middle frontal gyrus,right somatosensory cortex,left superior longitudinal fasciculus.MD and RD were increased in wide-ranging areas in irresponsive group.No difference in AD was observed.Conclusion: White matter alterations in above areas may affect the function of dopaminergic network,and thus may be associated with levodopa response in PD patients.DTI data suggests that there may be myelin damage in these area,but further researches are needed to analyze the specific mechanism and pathological changes.