The Value Of Hummingbird Sign Rating Scale In The Differential Diagnosis Of Progressive Supranuclear Palsy

Background and Objective: Progressive supranuclear palsy(PSP)is one of the atypical Parkinsonian syndromes(APS).The clinical manifestation is characterized by vertical supranuclear ophthalmoplegia and postural instability.There are many overlap of the symptoms of PSP and Parkinson's disease(PD),multiple system atrophy(MSA),corticobasal degeneration(CBD),dementia with Lewy bodies(DLB)and other atypical Parkinsonian syndromes,especially in the early stages of these diseases.Each of those diseases has different clinical subtypes,which increases the difficulty of early identification.However,the prognosis and therapy of PSP and other atypical Parkinson syndromes are not the same as PD.It is necessary to make an early diagnosis.The typical magnetic resonance imaging features of PSP conclude midbrain atrophy,superior cerebellar peduncles atrophy and signal changes,some patients have frontal or anterior frontal atrophy.Midbrain atrophy presents "hummingbird sign"(HBS)in the median sagittal plane and “morning glory sign” in axial plane.Although HBS is a distinctive feature of PSP,there is no uniform standard for the identification of HBS in the previous studies.In order to facilitate the accurate exchange between researchers,Kim et al formulated the hummingbird sign rating scale(HBS-RS)in 2015 to further standardize the diagnostic criteria of HBS.HBS-RS has been shown a higher diagnostic accuracy in distinguishing PSP from PD.The aim of this study is to further explore the value of HBS-RS in the differential diagnosis of PSP,PD,MSA-P and MSA-C in order to provide the evidence for the early diagnosis of PSP.Methods: This study retrospectively analyzed the clinical and neuroimaging data of 176 patients hospitalized in Neurology of the First Affiliated Hospital of DalianMedical University from January 2007 to November 2017.Among them,33 cases of PSP,37 cases of PD,38 cases of the MSA-C type,34 cases of the MSA-P type,and 34 cases of the controls were diagnosed by the experienced professors.All subjects underwented cerebral MRI to observe the T1 WI middle sagittal magnetic resonance imaging.The hummingbird sign was evaluated in two steps,including identification of the hummingbirds through personal experience assessment and according to the hummingbird emission radiology visual rating Scale.Five groups of subjects were blindly measured and scored 2 times,the first and second intervals of 1month.The HBS-RS consists of 4 items(shape of the third ventricular floor,shape of hummingbird beak,shape of hummingbird head,ratio of midbrain and pons),with weighted scores from 0 to 2.We used the SPSS and MedCalc software for statistical analysis of data.P<0.05 is considered as statistically significant.Results: The HBS-RS scores for each item and the composite score showed fair to good agreement(Cohen's kappa [?],0.503-0.701).Shape of the hummingbird beak being the highest and shape of the hummingbird's head being the lowest were observed in a single item.The level of sensitivity and specificity is affected by the cut-off point of each item or composite score.In HBS-RS,the specificity of using the composite score(6 for the sum of items # 1,# 2 and # 4 and 8 for all 4 items)was higher than 90% and the 2 composite scores(all the sum of the 4 items is 8 points)is nearly 100%.The Receiver Operating Characteristic(ROC)of the sum HBS-RS score showed that the two scores correctly diagnosed PSP(Area Under the Curve,AUC = 0.924 and 0.916),and there was no significant difference between the two scores in AUC(P=0.817 and0.520,respectively).Conclusion: HBS-RS is a simple,measurable visual assessment tool,which used to identify hummingbirds for the diagnosis of PSP with high inter-rater reliability and adjustable diagnostic validity.The HBS-RS provides a good application value for the differential diagnosis of PSP and its related diseases.