The Clinical And ¹⁸F-FDG PET Study On Idiopathic Parkinson Disease And Several Parkinsonism-plus Syndromes

Objectives:Idiopathic Parkinson disease(IPD)and parkinsonism-plus syndromes (PPS)such as multiple system atrophy(MSA),progressive supranuclear palsy(PSP), corticobasal degeneration(CBD)and dementia with Lewy bodies(DLB)are the most common movement disorders associated with neurodegenerative diseases.In the present study,detailed clinical investigations and neurological tests were performed on IPD and PPS patients to study the similarities and the differences in both neurological characteristics and MRI abnormalities.What's more,the regional cerebral glucometabolism in IPD and PPS was studied and the aim was to evaluate the differentiation of IPD,MSA,PSP,CBD and DLB based on FDG PET.Methods and materials:In Part one,120 subjects were collected from patients with a clinical diagnosis of neurodegenerative diseases,and were divided into IPD and PPS(including MSA-P,MSA-C,PSP,CBD and DLB).The data-base is followed up by inserting information on UPDRS scores,ADL scores,cognitive function investigations and MRI.In part two,PET using ¹⁸F-FDG was performed for IPD, MSA-P,MSA-C,PSP,CBD,DLB and NPH patients.In.addition,40 healthy control subjects were included in the analysis.Imaging-based diagnosis was obtained by visual assessment of the individual scans and also by statistical parametric mapping(SPM), to analyse the differentiations and overlaps among these groups.Results1 Although there are more overlaps of clinical parkinsonism characteristics between IPD and PPS,postural or action tremor,akinesia and rigidity were observed more in PPS,and the response to the levodopa is poorly in PPS.2 Patients in MSA-P group usually showed bradykinesia,all the MSA-C patients comprise cerebellar ataxia.82.35%of PSP patients are represented by motor impairments such as loss of balance and falls;88.24%occur the vertical supranuclear gaze palsy.Unilaterality or strong asymmetry is a defining feature of the parkinsonism symptoms of CBD.Cortical dysfunctions such as ideomotor apraxia,alien-limb phenomenon,frontal-lobe-release signs and dystonia is common in CBD group.The clinical features of DLB group are fluctuating cognitive impairment,recurrent visual hallucinations and parkinsonism.3 Impairment of autonomic dysfunctions was serious in MSA group and moderate in PSP group.Dementia is showed over 50%of PSP,CBD and DLB group.4 Findings were observed on MRI at 1.5 Tesla as atrophy and signal changes in the putamen,atrophy of the cerebellar and brainstem,midbrain or asymmetric atrophy of cortical and basal ganglia,these findings are all useful to distinguish these groups.5 Compared to controls,every group has its especially metabolic reductions.In MSA, the hypometabolism areas are mainly in bilateral putamen for MSA-P and bilateral cerebellum for MSA-C.The reductions of metabolism in midline frontal regions and midbrain is the characteristics of PSP.And in CBD,distinctive asymmetrical relative metabolic reductions were present cortical areas and basal ganglia.Also,the metabolic reductions in bilateral occipital cortex may be a marker of DLB.The metabolic reductions in a patient of normal pressure hydrocephalus(NPH)are showed around the ventricle system.6 In diseases of "tauopathies",the hypometabolism areas are mainly in bilateral frontal regions.Iin diseases of "synucleinopathies" such as IPD and DLB,relative metabolic reductions were present in bilateral parial cortex or bilateral occipital cortex.7 Using the SPM-supported reading method to evaluate PET images based on the characteristical metabolic reductions of each group,the correct imaging diagnosis was obtained in 86.15%of all subjects.Concordance with clinical diagnosis was 77.78% for IPD,86.36%for MSA,70%for MSA-P,100%for MSA-C,92.31%for PSP, 80%for CBD,and 86.5%for DLB.Conclusions:1 The subgroups of PPS have higher scores of UPDRS and ADL compaerd with the group of IPD,and their response to the levodopa are all poorer than IPD group's.2 Characteristical clinical signs were found in MSA,PSP,CBD and DLB,which can provide the prove for clinical diagnosis.Impairment of autonomic dysfunction especially orthostatic hypotension was serious in MSA,also more patients with PSP, CBD and DLB have cognitive deficits.Brain MRI offers the potential for objective criteria in the differential diagnosis of PPS,since it frequently shows characteristic abnormalities in the cortex,striatum,brainstem and cerebellum. 3 This study demonstrates the utility of FDG PET imaging in the differential diagnosis of patients with parkinsonism using SPM approach.The metabolic reductions in differential areas can differentiate IPD from PPS.The metabolic reductions in frontal cortex is the supporting feathers of PSP and CBD.4 FDG PET may contribute to early differential diagnosis in clinically ambiguous cases of parkinsonism.