Altered executive control network connectivity in anti-NMDA receptor encephalitis.

OBJECTIVE: The goal of this study was to examine whether the static functional connectivity (FC) of the executive control network (ECN) and the temporal properties of dynamic FC states in the ECN can characterize the underlying nature of anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis and their correlations with cognitive functions. METHODS: In total, 21 patients with anti-NMDA receptor encephalitis past the acute stage and 23 healthy controls (HCs) underwent a set of neuropsychological tests and participated in a resting-state fMRI study to analyse the static FC of the ECN and the temporal properties of dynamic FC states in the ECN. In addition, correlation analyses were performed to determine the correlations between the FC metrics and cognitive performance. RESULTS: Patients with anti-NMDA receptor encephalitis past the acute stage showed significant cognitive impairments compared to HCs. In accord with the results of neuropsychological tests, static intrinsic FC alterations and changed dynamic FC metrics of ECN were observed in the patients. Importantly, we observed significant correlations between altered ECN metrics and working memory, information processing speed, executive function performance in the patients. INTERPRETATION: Our findings suggest that cognitive impairments in patients with anti-NMDA receptor encephalitis past the acute stage are likely related to altered static and dynamic ECN connectivity. These observations may enhance our understanding of the pathophysiological mechanisms underlying cognitive function in this population.

Limbic encephalitis in a child with ovarian teratoma and influenza B. Case report and critical review of the history of autoimmune anti-N-methyl-d-aspartate receptor encephalitis.

We report the appearance of clinical symptoms and signs of N-methyl-d-Aspartate (NMDA) receptor encephalitis in a patient presenting just days after contraction of influenza B. The offending mature ovarian teratoma was identified and removed on the 10th day after the appearance of symptoms, with subsequent nearly complete resolution of symptoms over the subsequent 6 months. We provide a focused literature review of the clinical and pathophysiologic literature of anti-NMDA receptor encephalitis pertaining to influenza B virus and the pediatric population. Taken together, this study contributes to the pathophysiological understanding of anti-NMDA receptor encephalitis and aids clinicians in its early recognition and management.

Anti-NMDA receptor autoimmune encephalitis: a case report.

A 42-year-old, previously healthy female presented to her local doctor with insomnia, difficulty concentrating and impaired short-term memory. She denied illicit drug use. Fluoxetine and temazepam were initiated for anxiety. However, she later developed confusion and paranoid delusions, with an impression that her partner was attempting to kill her.

Altered EEG markers of synaptic plasticity in a human model of NMDA receptor deficiency: Anti-NMDA receptor encephalitis.

Plasticity of synaptic strength and density is a vital mechanism enabling memory consolidation, learning, and neurodevelopment. It is strongly dependent on the intact function of N-Methyl-d-Aspartate Receptors (NMDAR). The importance of NMDAR is further evident as their dysfunction is involved in many diseases such as schizophrenia, Alzheimer's disease, neurodevelopmental disorders, and epilepsies. Synaptic plasticity is thought to be reflected by changes of sleep slow wave slopes across the night, namely higher slopes after wakefulness at the beginning of sleep than after a night of sleep. Hence, a functional NMDAR deficiency should theoretically lead to altered overnight changes of slow wave slopes. Here we investigated whether pediatric patients with anti-NMDAR encephalitis, being a very rare but unique human model of NMDAR deficiency due to autoantibodies against receptor subunits, indeed show alterations in this sleep EEG marker for synaptic plasticity. We retrospectively analyzed 12 whole-night EEGs of 9 patients (age 4.3-20.8 years, 7 females) and compared them to a control group of 45 healthy individuals with the same age distribution. Slow wave slopes were calculated for the first and last hour of Non-Rapid Eye Movement (NREM) sleep (factor 'hour') for patients and controls (factor 'group'). There was a significant interaction between 'hour' and 'group' (p = 0.013), with patients showing a smaller overnight decrease of slow wave slopes than controls. Moreover, we found smaller slopes during the first hour in patients (p = 0.022), whereas there was no group difference during the last hour of NREM sleep (p = 0.980). Importantly, the distribution of sleep stages was not different between the groups, and in our main analyses of patients without severe disturbance of sleep architecture, neither was the incidence of slow waves. These possible confounders could therefore not account for the differences in the slow wave slope values, which we also saw in the analysis of the whole sample of EEGs. These results suggest that quantitative EEG analysis of slow wave characteristics may reveal impaired synaptic plasticity in patients with anti-NMDAR encephalitis, a human model of functional NMDAR deficiency. Thus, in the future, the changes of sleep slow wave slopes may contribute to the development of electrophysiological biomarkers of functional NMDAR deficiency and synaptic plasticity in general.

Pediatric N-Methyl-d-Aspartate (NMDA) Receptor Encephalitis, With and Without Herpes Encephalitis.

OBJECTIVE: To compare clinical, diagnostic, management, and outcome factors in children with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis and a history of herpes simplex encephalitis (HSE) to children with NMDAR encephalitis without a history of HSE. METHODS: All patients with anti-NMDAR antibodies in cerebrospinal fluid treated at our institution between 2012 and 2019 were identified and divided into those with a history of HSE (HSE+NMDAR group) and those without a history of HSE (NMDAR-only group). Demographic data, clinical characteristics, immunotherapy, and outcome data were collected on all patients and compared between the 2 groups. RESULTS: Seventeen patients were identified with anti-NMDAR antibodies in cerebrospinal fluid, 6 of whom had a history of HSE. Mean age in the HSE+NMDAR cohort was significantly younger in the HSE+NMDAR cohort, as 5 of the 6 patients were infants. Of HSE+NMDAR patients, 50% had behavioral symptoms, 67% had movement disorders, and 100% had seizures at disease nadir. In the NMDAR-only group, 100% had behavioral symptoms, 73% had movement disorders, and 73% had seizures at nadir. HSE+NMDAR patients received a median of 1 immunotherapy, compared to a median of 4.5 immunotherapies in the NMDAR-only group. CONCLUSION: Behavioral symptoms were more common in NMDAR-only patients, whereas seizures were more common in HSE+NMDAR patients. Both groups had significant disability at disease nadir, with more improvement in disability over time in the NMDAR-only group. HSE+NMDAR patients received fewer immunotherapies than NMDAR-only patients. Outcomes of infants with HSE appear to primarily reflect sequelae from HSE.

Clinical Features and Outcomes of Anti-N-Methyl-d-Aspartate Receptor Encephalitis in Infants and Toddlers.

OBJECTIVE: We describe the clinical features and outcomes of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in infants and toddlers. METHODS: This was a single-center retrospective study. Infants and toddlers who met the diagnostic criteria for anti-NMDAR encephalitis were recruited for the study. Data on clinical features, treatment, and long-term outcomes were collected retrospectively. RESULTS: A total of 41 patients (age range: six to 34 months; median age: 23 months; female: 19) were enrolled in this study. Nineteen (46%) patients exhibited classical anti-NMDAR encephalitis, whereas 22 (54%) patients exhibited anti-NMDAR encephalitis after viral encephalitis. There was a high presentation of movement disorders (100%), developmental regression (90%), abnormal behaviors (90%). All patients were administered first-line therapy, with only 17% of them being administered second-line immunotherapy. Two patients succumbed to the disease, whereas none of them relapsed. At the long-term follow-up (more than one year), 20 of 35 (57%) exhibited satisfactory outcomes (modified Rankin Scale ≤2). Compared with patients with classical anti-NMDAR encephalitis (n = 18), patients after viral encephalitis (n = 17) were more likely to have worse clinical outcomes. They exhibited a higher modified Rankin Scale/Pediatric Cerebral Performance Category score and more frequent seizures. A predictor of poor outcome was presentation after viral encephalitis (odds ratio 35.7, 95% confidence interval 4.64 to 275.03, P = 0.001). CONCLUSION: Anti-NMDAR encephalitis in infants and toddlers clinically presents with movement disorders, developmental regression, and abnormal behaviors. Interestingly, this group had a higher proportion of patients after viral encephalitis, which is regarded as the only risk factor for poor outcomes.

Using EEG and MEG to characterize extreme delta brush in a patient with anti-NMDA receptor encephalitis.

BACKGROUND: Extreme delta brush (EDB) is considered a potential marker for anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. The brain regions involved in EDB are unclear. CASE PRESENTATION: A 16-year-old woman with anti-NMDAR encephalitis who was experiencing psychosis was admitted. Electroencephalography (EEG) and magnetoencephalography (MEG) were used to analyze EDB in the patient. EDB on EEG could be disturbed by opening and closing the eyes, by occipital alpha rhythms and by sleep-wake cycles. The MEG results showed beta activity originating from bilateral superior parietal lobes. However, the delta wave originated from bilateral superior temporal gyri, the right middle temporal gyrus, the right inferior frontal gyrus, and the left inferior parietal lobe. CONCLUSIONS: Delta wave and beta activity might originate from different brain regions. Beta activity might be transmitted forward to the frontotemporal lobe and superimposed with delta activity to form EDB on EEG.

Seizures in autoimmune encephalitis-A systematic review and quantitative synthesis.

OBJECTIVE: This study aimed to evaluate the proportion of patients with seizures and electroencephalography (EEG) abnormalities in autoimmune encephalitis (AE) and its most common subtypes. METHODS: This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards and was registered with the International Prospective Register of Systematic Reviews (PROSPERO). We searched Medline All, Embase, and PsychINFO in Ovid from inception to June 2019 for articles pertaining to AE and seizure. Included studies reported seizure and/or EEG data in cohorts of ≥10 AE patients. Patient demographics, antibody type, seizure incidence, and EEG findings were extracted. Review of studies and data extraction were performed in duplicate. In addition to descriptive analysis, quantitative synthesis stratified by autoantibody subtype was performed with logistic regression and chi-square analyses. RESULTS: Our search yielded 3856 abstracts: 1616 were selected for full-text review and 118 studies met eligibility criteria. Of 3722 antibody-positive AE patients, 2601 (69.9%) had clinical seizures during the course of their illness. Of the 2025 patients with antibody-positive AE and available EEG data, 1718 (84.8%) had some EEG abnormality (eg, epileptiform discharges, slowing, and so on). Anti- N-methyl-d-aspartate (NMDA) receptor encephalitis (anti-NMDARE) was the most commonly reported type of AE (1985/3722, 53.3%). Of the anti-NMDARE patients with available seizure or EEG data, 71.8% (n = 1425/1985) had clinical seizures during their illness, and 89.7% (n = 1172/1306) had EEG abnormalities. For all AE patients and in the anti-NMDARE subpopulation, seizures were more common in younger patients (p < .05). SIGNIFICANCE: This systematic review provides an estimate of the proportion of AE patients with seizures, confirming the magnitude of seizure burden in this population. Prospective studies are needed to understand population-based prevalence of seizures, identify factors associated with seizures, and evaluate particular EEG findings as biomarkers of seizures and outcomes in AE.

Pediatric anti-N-methyl-d-aspartate receptor encephalitis in southern China: Analysis of 111 cases.

OBJECTIVE: To study the clinical features of children diagnosed with anti-NMDAR encephalitis in southern China. METHODS: Clinical data of children diagnosed with anti-NMDAR encephalitis from October 2014 to June 2020 from one national regional medical center were analyzed. Neurological disability was assessed by modified Rankin Scale (mRS) throughout the course of disease. RESULTS: 111 children (M/F = 49/62; mean onset age = 6.8 y) with anti-NMDAR encephalitis were involved. Prodromal events occurred in 34.2% of patients with infectious events being the most common. Seizure was the most common initial symptom, though movement disorder served as the most common event throughout the course of disease. 9.9% of patients had overlapped with other neuronal autoantibodies. Electroencephalogram showed abnormalities with slow wave (100.0%), epileptic discharge (31.5%) and delta brush (8.1%) respectively. 41.4% of patients had abnormal brain MRI, with focal lesions being the most common. None patients had tumor. 80.9% of patients had good response to first line therapy (steroid plus immunoglobulin), while 14 patients accepted second-line therapy (Rituximab) and all had a good response. Boys were significantly more likely to need more course of steroid. 13.8% of patients relapsed. 2 male patients died. mRS score was significantly improved after treatment. 51.4% of patients had a full recovery and 81.7% had mRS score ≤ 2. The median mRS score of boys after treatment was higher than that of girls. Non-infectious prodromal event, past medical history, perivascular lesions in brain MRI, hospital stay, initial mRS score higher than 3, and RTX treatment were independent risk factors associated with poor prognosis, defined as mRS score > 2. CONCLUSION: Of pediatric anti-NMDAR encephalitis in southern China: median onset age around 7 years; girls more common; boys might have poor outcome than girls; seizure or movement disorder respectively being most common onset or course symptom; a few overlapped with other neuronal autoantibodies; rare combined with tumor; most had a good response to immunotherapy and a good prognosis; relapse rate relatively high; fatality rate relatively low; some risk factors associated with poor prognosis.

Continuous EEG Findings in Autoimmune Encephalitis.

PURPOSE: Autoimmune encephalitis (AE) is a cause of new-onset seizures, including new-onset refractory status epilepticus, yet there have been few studies assessing the EEG signature of AE. METHODS: Multicenter retrospective review of patients diagnosed with AE who underwent continuous EEG monitoring. RESULTS: We identified 64 patients (male, 39%; white, 49%; median age, 44 years); of whom, 43 (67%) were antibody-proven AE patients. Of the patients with confirmed antibody AE, the following were identified: N-methyl-D-aspartate receptor (n = 17, 27%), voltage-gated potassium channel (n = 16, 25%), glutamic acid decarboxylase (n = 6, 9%), and other (n = 4, 6%). The remaining patients were classified as probable antibody-negative AE (n = 11, 17%), definite limbic encephalitis (antibody-negative) (n = 2, 3%), and Hashimoto encephalopathy (n = 8, 13%). Fifty-three percent exhibited electrographic seizures. New-onset refractory status epilepticus was identified in 19% of patients. Sixty-three percent had periodic or rhythmic patterns; of which, 38% had plus modifiers. Generalized rhythmic delta activity was identified in 33% of patients. Generalized rhythmic delta activity and generalized rhythmic delta activity plus fast activity were more common in anti-N-methyl-D-aspartate AE (P = 0.0001 and 0.0003, respectively). No other periodic or rhythmic patterns exhibited AE subtype association. Forty-two percent had good outcome on discharge. Periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome (OR, 6.4; P = 0.0012; OR, 3; P = 0.0372; OR, 12.3; P = 0.02, respectively). CONCLUSION: Our study confirms a signature EEG pattern in anti-N-methyl-D-aspartate AE, termed extreme delta brush, identified as generalized rhythmic delta activity plus fast activity in our study. We found no other pattern association with other AE subtypes. We also found a high incidence of seizures among patients with AE. Finally, periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome regardless of AE subtype.

Clinical and electrographic features of persistent seizures and status epilepticus associated with anti-NMDA receptor encephalitis (anti-NMDARE).

Based on a multicenter cohort of people with anti-NMDA receptor encephalitis (anti-NMDARE), we describe seizure phenotypes, electroencephalographic (EEG) findings, and anti-seizure treatment strategies. We also investigated whether specific electrographic features are associated with persistent seizures or status epilepticus after acute presentation. In this retrospective cohort study, we reviewed records of children and adults with anti-NMDARE between 2010 and 2014 who were included in the Rare Epilepsy of New York City database, which included the text of physician notes from five academic medical centers. Clinical history (e.g., seizure semiology) and EEG features (e.g., background organization, slowing, epileptiform activity, seizures, sleep architecture, extreme delta brush) were abstracted. We compared clinical features associated with persistent seizures (ongoing seizures after one month from presentation) and status epilepticus, using bivariate and multivariable analyses. Among the 38 individuals with definite anti-NMDARE, 32 (84%) had seizures and 29 (76%) had seizures captured on EEG. Electrographic-only seizures were identified in five (13%) individuals. Seizures started at a median of four days after initial symptoms (IQR: 3-6 days). Frontal lobe-onset focal seizures were most common (n=12; 32%). Most individuals (31/38; 82%) were refractory to anti-seizure medications. Status epilepticus was associated with younger age (15 years [9-20] vs. 23 years [18-27]; p=0.04) and Hispanic ethnicity (30 [80%] vs. 8 [36%]; p=0.04). Persistent seizures (ongoing seizures after one month from presentation) were associated with younger age (nine years [3-14] vs. 22 years [15-28]; p<0.01). Measured electrographic features were not associated with persistent seizures. Seizures associated with anti-NMDARE are primarily focal seizures originating in the frontal lobes. Younger patients may be at increased risk of epileptogenesis and status epilepticus. Continuous EEG monitoring helps identify subclinical seizures, but specific EEG findings may not predict the severity or persistence of seizures during hospitalization.

Paraneoplastic anti-NMDA receptor encephalitis in 1830?

OBJECTIVE: Our aim was to identify patients with probable anti-NMDA receptor encephalitis among historical medical cases. METHOD: A case report published in leading Hungarian-, German- and Italian-language medical journals in the early 1840s was revisited. RESULTS: In 1830, an 18-year-old, healthy woman suffered epileptic seizures, followed by a 6-day-long state characterized by catalepsy, unresponsiveness, motionless, and light breathing. Her symptoms regularly returned in the following 1.5 years. Meanwhile, a progressively growing huge abdominal tumor appeared. One day, she suddenly started vomiting a large amount of foul-smelling pus mixed with blood, accompanied by bone fragments. Pus mixed blood with some membranous substance was also evacuated through the anus and vagina. After this event, she completely recovered; 1.5 years later, she married and later gave birth to 3 healthy children. The patient remained healthy during the 11-year follow-up. CONCLUSIONS: We suggest that in the description of a paraneoplastic case, an anti-NMDA receptor encephalitis can be dated back as far as to the 19th century, with an especially rare type of resolution: the disappearance of the symptoms after the spontaneous elimination of an ovarian teratoma.

Reduced serial dependence suggests deficits in synaptic potentiation in anti-NMDAR encephalitis and schizophrenia.

A mechanistic understanding of core cognitive processes, such as working memory, is crucial to addressing psychiatric symptoms in brain disorders. We propose a combined psychophysical and biophysical account of two symptomatologically related diseases, both linked to hypofunctional NMDARs: schizophrenia and autoimmune anti-NMDAR encephalitis. We first quantified shared working memory alterations in a delayed-response task. In both patient groups, we report a markedly reduced influence of previous stimuli on working memory contents, despite preserved memory precision. We then simulated this finding with NMDAR-dependent synaptic alterations in a microcircuit model of prefrontal cortex. Changes in cortical excitation destabilized within-trial memory maintenance and could not account for disrupted serial dependence in working memory. Rather, a quantitative fit between data and simulations supports alterations of an NMDAR-dependent memory mechanism operating on longer timescales, such as short-term potentiation.

[Research progress on electroencephalogram characteristics of anti-N-methyl-D-aspartate receptor encephalitis].

Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis is a kind of autoimmune disease aiming at NR1 subunit of NMDA receptor. In the early stage, functional damage is the main cause. Electroencephalogram (EEG) can reflect the abnormal brain function by recording the changes of EEG signals. The common EEG patterns of anti NMDA receptor encephalitis are slow wave abnormality, epileptic discharge, a large number of ß activity, extreme delta brush, etc. Here we review the waveform characteristics, origin, pathogenesis and clinical value of EEG in patients with NMDA receptor encephalitis.

Psychiatric Prodrome in Anti-NMDAR-Associated Encephalopathy: Clinical and Pathophysiologic Considerations.

OBJECTIVE: To present a review of the literature on the clinical presentation and pathophysiology of anti-N-methyl-d-aspartate receptor encephalopathy (ANMDARE) with attention to both the more commonly recognized psychotic symptom prodrome and the less well-understood depressive symptom prodrome. DATA SOURCES: The search for clinical neuropsychiatric phenomena and proposed mechanisms involved in ANMDARE pathophysiology was conducted in PubMed. English-language articles published up to September 2019 were identified using a combination of the following search terms: N-methyl-d-aspartate, anti-NMDA receptor encephalitis, schizophrenia, psychosis, depression, major depressive disorder, bipolar I disorder, bipolar II disorder, anxiety, and posttraumatic stress disorder. STUDY SELECTION: From 150 articles identified from the initial search, the 73 most relevant clinical studies, reviews, and case reports related to the study objectives were included. DATA EXTRACTION: Sources were individually analyzed by the 3 authors for the most clinically relevant information. RESULTS: The pathophysiology and mechanisms involved in anti-NMDA receptor antibody delivery to the brain are incompletely characterized, but antibody binding appears to involve the GluN1 subunit in most cases. Psychotic symptoms are the most commonly recognized components of prodromal psychiatric illness in ANMDARE, which may lead to an initial diagnosis of schizophrenia. In addition to psychotic symptoms, there are reports of depressive symptoms occurring before the emergence of, co-occurring with, or instead of psychotic symptoms in ANMDARE. CONCLUSIONS: In addition to the better-known psychotic prodrome, depressive symptomatology can occur in ANMDARE patients. ANMDARE should be considered in patients with initial presentation of either psychotic or atypical depressive illnesses. Early recognition of these psychiatric prodromal states as antecedents to ANMDARE could lead to improved diagnosis and better management of this potentially life-threatening autoimmune disorder.

Optic neuritis associated with anti-NMDA receptor antibody in the remission phase of anti-NMDA receptor encephalitis.

Optic neuritis is an inflammatory demyelinating disorder of the central nervous system. Anti-NMDA receptor (NMDAR) antibodies encephalitis is also mediated by the inappropriate immunological response. We report a girl who was readmitted because of unilateral eye pain and vision impairment in the remission period of anti-NMDAR encephalitis. Based on the limited available literature on the treatment of optic neuritis associated with anti-NMDA receptor antibody, she was treated with a combination of corticosteroids and intravenous immunoglobulin with clinical improvement. Optic neuritis in the remission phase of anti-N-methyl-D-aspartate receptor encephalitis remains relatively uncommon. It is important to document and follow these patients to understand the pathogenesis of optic neuritis in the setting of anti-NMDAR encephalitis and formulate effective therapeutic strategies.

Current Progress on Assessing the Prognosis for Anti-N-Methyl-D-Aspartate Receptor (NMDAR) Encephalitis.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common antineuronal antibody encephalitis in autoimmune encephalitis found at present. It has complex clinical manifestations such as psychiatric and behavioral abnormalities, seizures, movement disorders, consciousness, and autonomic dysfunction. The relationship between those manifestations and prognosis is unclear. Electroencephalography (EEG) is gradually becoming useful in the evaluation of the prognosis of anti-NMDAR encephalitis patients, while imaging and antibody testing have a limited prognostic value. Starting the patients on adequate treatments (such as immunotherapy) in a timely fashion has a positive impact on their prognosis. Nevertheless, research on the prognosis of anti-NMDAR encephalitis remains scarce. Here, we review the current advances of prognosis-related research from the clinical manifestations of the disease and auxiliary examinations such as EEG, magnetic resonance imaging (MRI), 18F fluorodeoxyglucose positron emission tomography (FDG-PET), and antibody measurement. In addition, we also discuss the impact of different treatment options on prognosis. In-depth research on the prognosis of patients with anti-NMDAR encephalitis will contribute to a better understanding of this disease, leading to better treatments options and, ultimately, a better prognosis.

Risk factors for pneumonia in patients with anti-NMDA receptor encephalitis: A single-center retrospective study.

To identify the risk factors of pneumonia in patients with Anti-N-methyl-D-aspartate (Anti-NMDA) receptor encephalitis.This is a retrospective study.Department of Neurology in West China Hospital of Sichuan University.Patients with a definitive diagnosis of anti-NMDA receptor encephalitis.Risk factors associated with pneumonia were examined by bivariate analysis and multivariate logistic regression model.A total of 104 patients were included in this study, of which 41% patients (n = 43) were diagnosed with pneumonia at 7 days (range: 4-40 days) after admission. The occurrence of pneumonia was associated with prolonged hospital stays, a higher rate of poor outcome, and extra healthcare costs. Risk factors associated with pneumonia included Glasgow coma scale score (GCS), abnormal movements and hypokalemia.Pneumonia is a common complication in anti-NMDA receptor encephalitis. In the present study, we found that disorders of consciousness, abnormal movements, and hypokalemia were independent risk factors for pneumonia in inpatients with anti-NMDA receptor encephalitis. Pneumonia prolongs the patients' hospital stay, hospitalization expenditures, and affects the patients' prognosis.