Clinical Features,Functional Outcomes,and Relapse Of Myelin-Oligodendrocyte Glycoprotein-Antibody-Associated Encephalitis

Background and Objective:Encephalitis is one of the important clinical phenotypes of MOG-antibodyassociated disease(MOGAD).Currently,the clinical studies on the encephalitis phenotype of MOGAD are limited,and its clinical features and prognosis are still not completely clear.The purpose of this study was to describe the clinical features,functional outcomes,and relapse of MOG-antibody-associated encephalitis(MOGAE),analyze the differences between children and adults and explore factors associated with disease severity and relapse.Methods:We retrospectively and prospectively collected the clinical data of MOGAE patients admitted to the First Hospital of Jilin University from June 2018 to December2022.The Clinical Assessment Scale for Autoimmune Encephalitis(CASE)and modified Rankin scale(m RS)were applied to evaluate the baseline severity of encephalitis.Functional outcomes at the last follow-up were evaluated using the m RS and the Mini-Mental State Examination.According to age at onset,baseline CASE score,and whether they had a relapse,patients were divided into children and adult groups,mild and severe groups,and monophasic and relapsed groups,respectively.Then we compared the differences in clinical data between groups and analyzed the factors associated with the disease severity and relapse of MOGAE.Results:(1)A total of 33 patients(18 children and 15 adults)were included,with an average age at onset of 17.9 years old,including 22 cases in the mild group and 11 cases in the severe group.Acute symptomatic seizures(72.7%),fever(63.6%),headache(72.7%),and lower level of consciousness(45.5%)were the most common symptoms.87.5% of patients had elevated cerebrospinal fluid white blood cell count,84.8% had abnormal brain MRI,and 81.8% had cortical lesions.89.3% of patients had abnormal interictal electroencephalography,71.4% had interictal epileptiform discharges,and42.3% had slow waves.In the acute phase,39.4% of patients received intravenous highdose methylprednisolone therapy alone,and 60.6% of patients received intravenous high-dose methylprednisolone combined with immunoglobulin therapy.After acute treatment,symptoms were significantly relieved,and then all patients received maintenance immunotherapy.(2)Compared with children,headache was more common in adults(P=0.021).Intensive care unit admission rate(P=0.047)and serum homocysteine level(P=0.025)were higher in adults than in children.Intravenous high-dose methylprednisolone alone in the acute phase was more frequently applied in adults(P<0.001),while high-dose methylprednisolone combined with immunoglobulin was more frequently applied in children(P<0.001).(3)Compared with the mild group,the positive rate of NMDAR-Ig G in cerebrospinal fluid(P=0.022),white blood cell count in cerebrospinal fluid(P=0.010),and serum homocysteine level(P=0.048)in the severe group were higher.At the same time,in the severe group,the proportion of adults was slightly higher(P=0.061),and the serum uric acid level was slightly lower(P=0.056).(4)Of the 30 patients with follow-up duration >6 months(median 20 months),23.3% relapsed,and 6.7% had a poor outcome(m RS ≥2)at the last follow-up.Encephalitis concomitant optic neuritis(P=0.031)was more common in the relapsed group.At the same time,the incidence of delayed immunotherapy in the relapsed group was also slightly higher than those in the monophasic group(P=0.060).There was no significant difference in functional outcomes and relapse between children and adults.Conclusions:1.Several clinical features and treatments differed between children and adults.Headache,intensive care unit admission,and higher serum homocysteine level were more common in adults.2.Cerebrospinal fluid NMDAR-Ig G positive,elevated cerebrospinal fluid white blood cell count,and elevated serum homocysteine level might be risk factors for the severity of MOGAE.3.The majority(93%)of MOGAE patients had favorable functional outcomes at the last follow-up(median follow-up of 20 months).4.The relapse rate of MOGAE was approximately 23%.Concomitant optic neuritis during encephalitis might be associated with relapse.