The Influence Of Corticomedullary Junction Hyperintensity In Diffusion Weighted Imaging Of Adult-onset NIID On Brain Connections

Objective:To explore the influence of corticomedullary junction(CMJ)hyperintensity in diffusion weighted imaging(DWI)of adult-onset neuronal intranuclear inclusion disease(NIID)on short-and long-range fibers in local and in whole brain.And to explore the correlation between short-and long-range fibers and cognitive dysfunction,along with changes of short-and long-range functional connections and their correlation to cognitive impairment.Background:A characteristic brain magnetic resonance imaging(MRI)feature of adult-onset NIID is the CMJ hyperintensity in DWI.However,little is known about its consequences on brain structure and function.CMJ is a special brain anatomic region containing both long-range fibers for supporting diverse and complex brain dynamics and short-range fibers for connections between adjacent gyri of the brain.Cognitive impairment is the main clinical manifestation of this disease.The influence of CMJ hyperintensity in DWI on these two kinds of fibers may change short-and long-range functional connections.And this process may play an important role in the development of cognitive dysfunction.Methods:9 adult-onset NIID subjects and 7 healthy controls were studied in our study.Short-and long-range fibers and functional connections were quantitatively analyzed between NIID subjects and healthy controls using diffusion tensor imaging(DTI),fiber tractography and resting-state functional magnetic resonance imaging(rf MRI).And we investigated the association between connections and cognitive dysfunction of adult-onset NIID.Results:Compared to healthy controls,the number and fraction of long-range fibers related with abnormal CMJ of adult-onset NIID group decreases(p<0.006 and p<0.001,respectively).The number of short-range fibers increases(p=0.013).In whole brain,the number and fraction of long-range fibers drops(p=0.006 and p<0.001,respectively).The number of short-range fibers doesn't show significant changes.In whole brain,the fraction of frontal,temporal,parietal and occipital long-range fibers don't show significant changes when compared to healthy controls.However,the number of frontal,temporal,parietal and occipital long-range fibers decrease significantly(p=0.029,p=0.003,p=0.024 and p=0.019 respectively).On the contrary,the number of frontal,temporal,parietal and occipital short-range fibers don't show significant changes.The fraction of frontal short-range fibers increases(p=0.024),but the fraction of temporal and occipital short-range fibers decrease(p=0.002and p=0.009,respectively).The fraction of parietal short-range fibers doesn't show significant changes.Short-ang long-range FCS also decrease compared to healthy controls(p<0.001).And damage of long-range FCS is severer than short-range FCS(p<0.001).Finally,we find that the fraction of long-range fibers is related to cognitive dysfunction(MMSE:p=0.039,R~2=0.480;Mo CA:p=0.097,R~2=0.345).It can be an indicator for evaluating the severity of cognitive dysfunction of adult-onset NIID patients.Conclusion:The number and fraction of long-range fibers decrease in both abnormal CMJ area and whole brain in adult-onset NIID.The damage to long-range fibers in abnormal CMJ is severer than in whole brain.And the number of short-range fibers increases in abnormal CMJ area.The reduction of long-range fibers exists in frontal,temporal,parietal and occipital lobe.However,the increase of short-range fibers mainly exists in the frontal lobe.Short-and long-range FCS decrease and long-range FCS decreases more severely than short-range FCS.The fraction of long-range fibers is related to cognitive dysfunction.