Clinical Characteristics Of Patients With Anti NMDA Receptor Encephalitis And Its Correlation With CSF Antibody Titer

Objective:Anti-N-methyl-D-aspartic acid(NMDA)receptor encephalitis is the most common autoimmune encephalitis.The diagnosis mainly depends on the detection of specific anti-NMDA receptor antibody in cerebrospinal fluid(CSF).To varying degrees,there were also differences in antibody titers.At present,there are few reports about the exact relationship between antibody titer and clinical characteristics of patients.It is not clear whether the CSF antibody titer has the significance of evaluating the disease and guiding diagnosis and treatment.It is also controversial whether the specific antibody is the only pathogenic factor of the disease.The purpose of this study is to summarize the clinical characteristics and outcome of anti NMDA receptor encephalitis and analyze the correlation between anti NMDA receptor encephalitis and CSF antibody titer.Methods:A retrospective analysis was performed of cases with anti-NMDA receptor encephalitis continuously diagnosed in the Department of Neurology,the First Hospital of Shanxi Medical University from June 2012 to March 2019.The demographics,clinical characteristics,and prognosis of these patients were summarized.Comparisons were made between low antibody titers(1:10,1:32)and high antibody titers(1: 100,1: 320)in cerebrospinal fluid.Results:Of the 38 patients,14(36.8%)were in the group of low antibody titer,and 24(63.2%)were in the group of high antibody titer.29 patients had prodromal symptoms,the common prodromal manifestations were fever(47.4%),headache(44.7%),respiratory symptoms(18.4%),life events(10.5%),among which headache was more common in the low antibody titer group,and the difference was statistically significant(71.4% vs 29.2%,P = 0.018).Psychobehavioral disorder or cognitive impairment(97.4%),epilepsy(78.9%),dyskinesia(58.0%),decreased level of consciousness(58.0%)were the common clinical manifestations.There was no significant difference between the two groups,and speech dysfunction was more common in low antibody titers(71.4%vs 33.3%,p = 0.042).The positive rate of serum antibody in patients was 47.4%.Compared with the low titer group,the positive rate of serum antibody was higher in high titer patients(62.5% vs 21.4%,p = 0.020).There was no significant difference between the two groups in terms of whether to stay in intensive care unit(ICU),whether to intubate,the number of days to stay in ICU,the time from symptoms to clear diagnosis,and complications.Most of the patients had a good prognosis(mRS score 0-2was 97.4%).Most of the patients could recover to the premorbid state within 2-3 months after discharge,and a few of them were still getting better several years after discharge.Conclusion:CSF antibody has only diagnostic significance in patients with anti-NMDA receptor encephalitis.For the same patient,the decrease of CSF antibody titer usually means the treatment is effective and the condition is improved.The persistence of antibody titers suggested a poor prognosis,and for female patients,it is suggested that there may be potential trigger factors such as tumor,and ovarian teratoma should be screened repeatedly.However,in different patients,the significance of CSF antibody titer in assessing disease severity and guiding diagnosis and treatment is limited,which may be related to the different affinity of autoantibodies among different patients,suggesting that there may be other factors involved in the pathogenesis of anti-NMDA receptor encephalitis.This study showed that single CSF antibody titer could not be used as oneof the factors to evaluate the severity and prognosis of the disease.