Comparison Of Clinial Characteristics Between Viral Encephalitis And Autoimmune Encephalitis And A Preliminary Study Of PrP^C In Their Differential Diagnosis

Objective: Viral encephalitis（VE）is an intracranial infectious disease caused by viruses.Autoimmune encephalitis（AE）generally refers to a class of encephalitis mediated by autoimmune mechanisms.There are similarities in clinical manifestations and biochemical examinations,especially in the early stage of the disease,which brings great difficulties to clinical differential diagnosis and affects the formulation of diagnosis and treatment for patients.The purpose of this study is to seek the differential diagnosis of viral encephalitis and autoimmune encephalitis from the following aspects: 1.Comparative analysis of clinical features of VE and AE;2.Differential diagnosis of VE and AE by CSF PrP^C;3.Value of cerebrospinal fluid（CSF）indexes in differential diagnosis of VE and AE.Methods:1.Comparative analysis of clinical features in patients with VE and AE: The study subjects were outpatients and inpatients who visited the First Hospital of Jilin University from January 2021 to January 2022.A total of 99 patients diagnosed with AE（n=48）,VE（n=30）,tuberculous encephalitis（n=9）,suppurative encephalitis（n=12）were enrolled.General information,such as age and sex,clinical manifestations,imaging,electrophysiological examination,CSF and blood test indexes of patients were collected.SPSS 26.0 software was used to analyze and compare the differences between the two groups.2.CSF PrP^C has differential diagnostic value for VE and AE: PrP^C expression in CSF of patients with encephalitis.CSF was collected from the same batch of patients who visited the First Hospital of Jilin University from January 2021 to January 2022.CSF was collected and frozen at-80℃.The content of PrP^C in CSF was determined by Elisa.SPSS 26.0 software,Graph Pad Prism 8 and Med Calc software were used for difference analysis of the results.3.Value of CSF indexes in differential diagnosis of VE and AE: We did ROC analysis with CSF indexes-PrP^C,white blood cell,protein,Ig G and pressure and evaluated the differential diagnosis value in VE and AE.Results:1.Comparative analysis of clinical features in patients with VE and AE: Most patients in VE group were male,and most patients in AE group were female.In terms of the onset symptoms,most of the patients in VE group had prodromal symptoms,accounting for 76.67%,followed by epilepsy.In the AE group,the onset symptoms were more complex and varied.In terms of clinical manifestations,fever,headache,positive Kernig Sign,hypoventilation of central nervous system and disturbance of consciousness were more common in VE group than in AE group（all P<0.05）.In terms of imaging examination,abnormalities of temporal lobe,insula/hippocampus were more common in VE patients（P<0.05）.In terms of CSF indexes,CSF pressure,WBC,protein and Ig G in VE group were higher than those in AE group（P<0.05）.In terms of blood test,eosinophil count,lymphocyte count,high density lipoprotein and calcium ion in AE group were higher than those in VE group（P<0.05）.The ratio of neutral granule to lymphocyte,C-reactive protein,total bilirubin and direct bilirubin in VE group were higher than those in AE group（P<0.05）.2.CSF PrP^C has differential diagnostic value for VE and AE: The content of PrP^C in the infectious encephalitis,including VE,tuberculous encephalitis and suppurative encephalitis was significantly higher than that in patients with AE（P<0.05）.However,there was no statistical difference in CSF PrP^C between subgroups of infectious encephalitis.There was no significant difference in CSF PrP^C between the awake group and the coma group.There was no significant correlation between CSF PrP^C and GCS score.With the recovery of disease,CSF PrP^C of most VE patients decreased（P<0.05）.PrP^C in CSF increased in most patients with VE with the recovery of disease,but there was no significant difference in PrP^C content between the first and last lumbar puncture.3.Value of CSF indexes in differential diagnosis of VE and AE: We did the differential diagnosis of VE and AE by combing various indexes of CSF.Combination 1 was composed of PrP^C,white blood cell,protein,Ig G and pressure,the AUC value was 0.87（95%CI: 0.76-0.95）,with sensitivity 68.00% and specificity 96.87%.Combination 2 was composed of white blood cell,protein,Ig G and pressure,the AUC value was 0.86 0.84（95% CI:0.72-0.93）,with sensitivity 92.00% and specificity 68.75%.Conclusion:1.There are differences between VE and AE in general characteristics,clinical manifestations and auxiliary examinations.2.CSF PrP^C was statistically different between patients with infectious encephalitis and AE which was not related to pathogen type.CSF PrP^C is expected to be a potential marker for differential diagnosis.3.The combination of CSF PrP^C,pressure,leukocyte,protein and Ig G is helpful for the differential diagnosis of VE and AE.