Diffusion Tensor Imaging Study Of Olfactory Disorder In Patients With Parkinson's Disease

Background and Objective:Parkinson's disease(PD)is a common neurological dyskinesia in middle-aged and elderly people.The main pathological change is the progressive loss of dopaminergic neurons in the dense part of the substantia nigra.The remaining dopamine neurons form an eosinophilic inclusion body,namely Lewy body(LB),the main component is ?-synuclein(?-syn),eventually caused a significant decrease in dopaminergic neurotransmitters in the striatum and an imbalance between dopamine and acetylcholine.Parkinson's disease starts insidious and progresses slowly,motor symptoms include resting tremor,rigidity,bradykinesia,abnormal posture balance.Non-motor symptoms include olfactory disorder,sleep disorder,intractable constipation,mood disorder,and cognitive dysfunction.Both domestic and foreign studies have found that non-motor symptoms have a greater impact on patients' quality of life than motor symptoms,and have emerged in the early stages of PD.The study found that olfactory disorder(OD)may be the first non-motor symptom of PD.The incidence of OD in PD patients is as high as 45.0%~96.7%,but it is very rare to be the chief complaint.The study found that olfactory disorders are associated with the severity and rapid progression of PD,and are associated with cognitive impairment in patients.A severe olfactory decline in PD patients indicates an increased risk of progression to Parkinson's disease dementia.Mild olfactory disorder does not affect the quality of life of patients,but olfactory disorders can be aggravated with age,and can seriously affect patients' quality of life,mood and personal safety.Therefore,early screening and recognition of olfactory disorders play an important role in the clinical diagnosis of PD and the discovery of preclinical PD.Timely treatment can provide a better quality of life for PD patients.At present,the use of magnetic resonance diffusion tensor imaging(DTI)technology to study the changes of PD microstructure has become one of the research hotspots of PD.Both domestic and international scholars have applied DTI technology to PD olfactory disorders and found abnormalities in the brain microstructure of PD patients.In addition,several studies have found that the early diagnosis of PD can be identified by analyzing the different parameters of DTI,which has significant significance for the early diagnosis of PD.At present,DTI research on PD olfactory disorders at home and abroad mostly adopts voxel analysis or region of interest processing methods,which is prone to subjective error and poor reproducibility,and the changes in brain microstructure are concentrated in the olfactory-related brain region.There are few studies on olfactory related white matter fiber bundles.In this study,the white matter fiber bundles were automatically named by DTI based on the tract-based spatial statistics(TBSS)method,and the changes of white matter fiber bundles in PD patients were analyzed.Sniffin' Sticks olfactory test was used to evaluate olfactory function.The purpose of this study was to investigate the relationship between abnormalities of white matter fiber bundles and PD with olfactory disorders,and to further explore the correlation between olfactory disorders and PD disease progression.In order to provide an important reference and basis for early detection,early diagnosis and early treatment of PD.Methods:Continuously collected 48 patients with Parkinson's disease who met the conditions in the Department of Neurology,the First Affiliated Hospital of Zhengzhou University from January 2018 to December 2018.According to Sniffin' Sticks olfactory test results,they were divided into two groups: Parkinson's disease with olfactory disorder(PD-OD)was performed in 35 patients,Parkinson's disease without olfactory disorder(PD-NOD)in 13 patients,among them,there were 19 cases of hyposmia and 16 cases of anosmia in the PD-OD group,and 29 volunteers in the same period were selected as the healthy controls.Using the Hoehn-Yahr(H-Y)grading scale and the Unified Parkinson's Disease Rating Scale motor part-III(UPDRS-III),the severity of exercise and motor function in patients with PD to evaluate.All subjects underwent magnetic resonance DTI examination,and the FMRIB Software Library(FSL)software was used to process the magnetic resonance images of PD patients and healthy controls,and the fractional anisotropy(FA)of 48 white matter fiber bundles were obtained.According to the tract-based spatial statistics(TBSS)analysis,38 white matter fiber bundles with different sensitivities in the PD group and the healthy control group were obtained,after consulting the literature,the olfactory related includes 11 fiber bundles,respectively,the middle cerebellar peduncle,genu of corpus callosum,body of corpus callosum,splenium of corpus callosum,right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),right cingulum(cingulate gyrus),left cingulum(cingulate gyrus),right fornix(cres)/stria terminalis,left fornix(cres)/stria terminalis,left uncinate fasciculus.The 11 fiber bundles were first statistically analyzed between the PD group and the control group,remove fiber bundle without statistical significance,and then statistical analysis was performed between the PD anosmia group,the hyposmia group,and the PD-NOD group to obtain statistically significant fiber bundles related to olfaction in this study,and then correlated with the olfactory test scores in the PD-OD group,and compared with the olfactory test in the value associated fiber bundle,and finally the PD patients olfactory test scores and age,disease duration,H-Y grading,UPDRS-? scores do further correlation analysis,process analysis the extent of olfactory disorders associated with the progression of PD disease.Results:1.There were 35 patients(72.9%)in the PD-OD group and 13 patients(27.1%)in the PD-NOD group.In the PD-OD group,24 patients(68.6%)complained of olfactory disorders,among them,19 patients(79.2%)had symptoms before PD symptoms;5 patients(20.8%)appeared in the course of motor symptoms,and 11 patients(31.4%)were found to have olfactory disorder at the time of treatment.2.Compared with the control group,the PD group had white matter fiber bundles in the middle cerebellar peduncle,genu of corpus callosum,body of corpus callosum,splenium of corpus callosum,right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),right cingulum(cingulate gyrus),left cingulum(cingulate gyrus),left uncinate fasciculus was statistically significant(P<0.05).The mean value of the FA value of the fiber bundle of the PD group was lower than that of the control group.3.The statistically significant white matter fiber bundles in the PD group and the control group were further statistically analyzed between the PD anosmia group,the hyposmia group,and the PD-NOD group,found in the middle cerebellar peduncle,right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),right cingulum(cingulate gyrus),left uncinate fasciculus difference was statistically significant(P<0.05),in the pairwise comparison,the right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus)were found to be statistically different between the olfactory anosmia group and the PD-NOD group(P<0.05).4.The FA values of the fiber bundles with statistical significance between the PD anosmia group,the hyposmia group,and the PD-NOD group were further correlated with the PD-OD group olfactory test scores,and positive correlation was found between the middle cerebellar peduncle,right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),right cingulum(cingulate gyrus)and the olfactory test score of PD patients(P<0.05).5.There was no correlation between olfactory test scores of PD patients and age,course of disease,H-Y grade,and UPDRS-III scores(P>0.05)..Conclusions:1.Damage to the olfactory-associated white matter fiber bundle in the brain of patients with PD olfactory disorder may be one of its potential pathogenesis.2.The severity of olfactory disorder in PD patients may indicate the degree of damage in the middle cerebellar peduncle,right sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),left sagittal stratum(include inferior longitidinal fasciculus and inferior fronto_occipital fasciculus),right cingulum(cingulate gyrus).Olfactory testing combined with DTI examination may be helpful for early diagnosis of PD.3.Olfactory disorder is a common non-motor symptom of PD,most of which occurs before PD motor symptoms,and was not associated with age,disease duration,H-Y grade,and UPDRS-III score.