The role of substantia nigra sonography in the differentiation of Parkinson’s disease and multiple system atrophy

摘要

Background:The differential diagnosis of Parkinson’s disease(PD)and multiple system atrophy(MSA)remains a challenge,especially in the early stage.Here,we assessed the value of transcranial sonography(TCS)to discriminate non-tremor dominant(non-TD)PD from MSA with predominant parkinsonism(MSA-P).Methods:Eighty-six MSA-P patients and 147 age and gender-matched non-TD PD patients who had appropriate temporal acoustic bone windows were included in this study.All the patients were followed up for at least 2 years to confirm the initial diagnosis.Patients with at least one substantia nigra(SN)echogenic size≥18 mm^(2) were classified as hyperechogenic,those with at least one SN echogenic size≥25 mm^(2) was defined as markedly hyperechogenic.Results:The frequency of SN hyperechogenicity in non-TD PD patients was significantly higher than that in MSA-P patients(74.1%vs.38.4%,p<0.001).SN hyperechogenicity discriminated non-TD PD from MSA-P with sensitivity of 74.1%,specificity of 61.6%,and positive predictive value of 76.8%.If marked SN hyperechogenicity was used as the cutoff value(≥25 mm^(2)),the sensitivity decreased to 46.3%,but the specificity and positive predictive value increased to 80.2 and 80.0%.Additionally,in those patients with SN hyperechogenicity,positive correlation between SN hyperechogenicity area and disease duration was found in non-TD PD rather than in MSA-P patients.In this context,among early-stage patients with disease duration≤3 years,the sensitivity,specificity and positive predictive value of SN hyperechogenicity further declined to 69.8%,52.2%,and 66.7%,respectively.Conclusions:TCS could help discriminate non-TD PD from MSA-P in a certain extent,but the limitation was also obvious with relatively low specificity,especially in the early stage.