Clinical Characteristics of Anti-GABA-B Receptor Encephalitis

MR Imaging Findings in Anti-Leucine-Rich Glioma Inactivated Protein 1 Encephalitis: A Systematic Review and Meta-analysis

BACKGROUND

Antibodies against leucine-rich glioma inactivated protein 1 (LGI1) constitute a common form of autoimmune encephalitis. On MR imaging, it may show T2 FLAIR hyperintensities of the medial temporal lobe (T2 FLAIR-MTL), involve the basal ganglia, or be unremarkable.

PURPOSE

We performed a systematic review and meta-analysis to obtain prevalence estimates of abnormal findings on MR imaging in anti-LGI1 encephalitis. A human brain map of the LGI1 microarray gene expression was derived from the Allen Human Brain Atlas.

DATA SOURCES

PubMed and Web of Science were searched with the terms "LGI1" and "encephalitis" from inception to April 7, 2022.

STUDY SELECTION

Thirty-one research publications, encompassing case series and retrospective cohort and case-control studies, with >10 patients with anti-LGI1 encephalitis and MR imaging data were included.

DATA ANALYSIS

Pooled prevalence estimates were calculated using Freeman-Tukey double-arcsine transformation. Meta-analysis used DerSimonian and Laird random effects models.

DATA SYNTHESIS

Of 1318 patients in 30 studies, T2 FLAIR-MTL hyperintensities were present in 54% (95% CI, 0.48-0.60; I2 = 76%). Of 394 patients in 13 studies, 27% showed bilateral (95% CI, 0.19-0.36; I2 = 71%) and 24% unilateral T2 FLAIR-MTL abnormalities (95% CI, 0.17-0.32; I2 = 61%). Of 612 patients in 15 studies, basal ganglia abnormalities were present in 10% (95% CI, 0.06-0.15; I2 = 67%). LGI1 expression was highest in the amygdala, hippocampus, and caudate nucleus.

LIMITATIONS

Only part of the spectrum of MR imaging abnormalities in anti-LGI1 encephalitis could be included in a meta-analysis. MR imaging findings were not the main outcomes in most studies, limiting available information. I2 values ranged from 62% to 76%, representing moderate-to-large heterogeneity.

CONCLUSIONS

T2 FLAIR-MTL hyperintensities were present in around one-half of patients with anti-LGI1. The prevalence of unilateral and bilateral presentations was similar, suggesting unilaterality should raise the suspicion of this disease in the appropriate clinical context. Around 10% of patients showed basal ganglia abnormalities, indicating that special attention should be given to this region. LGI1 regional expression coincided with the most frequently reported abnormal findings on MR imaging. Regional specificity might be partially determined by expression levels of the target protein.

Interest of rare autoantibodies in autoimmune encephalitis and paraneoplastic neurological syndromes: the utility (or futility) of rare antibody discovery

PURPOSE OF REVIEW

The increasing recognition and diagnosis of autoimmune encephalitis (AE) and paraneoplastic neurological syndromes (PNS) is partly due to neural autoantibody testing and discovery. The past two decades witnessed an exponential growth in the number of identified neural antibodies. This review aims to summarize recent rare antibody discoveries in the context of central nervous system (CNS) autoimmunity and evaluate the ongoing debate about their utility.

RECENT FINDINGS

In the last 5 years alone 15 novel neural autoantibody specificities were identified. These include rare neural antibody biomarkers of autoimmune encephalitis, cerebellar ataxia or other movement disorders, including multifocal presentations.

SUMMARY

Although the clinical applications of these rare antibody discoveries may be limited by the low number of positive cases, they still provide important diagnostic, prognostic, and therapeutic insights.

Study on clinical features and factors related to long-term outcomes of antibody-negative autoimmune encephalitis

OBJECTIVE

To delineate the clinical characteristics of antibody-negative autoimmune encephalitis (AE) and to investigate factors associated with long-term outcomes among antibody-negative AE.

METHODS

Patients diagnosed with antibody-negative AE were recruited from January 2016 to December 2022 at the Second Xiangya Hospital of Central South University. The study assessed the long-term outcomes of antibody-negative AE using the modified Rankin scale (mRS) and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). Predictors influencing long-term outcomes were subsequently analyzed. External validation of RAPID scores (refractory status epilepticus [RSE], age of onset ≥60 years, ANPRA [antibody-negative probable autoimmune encephalitis], infratentorial involvement, and delay of immunotherapy ≥1 month) was performed.

RESULTS

In total, 100 (47 females and 53 males) antibody-negative AE patients were enrolled in this study, with approximately 49 (49%) experiencing unfavorable long-term outcomes (mRS scores ≥3). Antibody-negative AE was subcategorized into ANPRA, autoimmune limbic encephalitis (LE), and acute disseminated encephalomyelitis (ADEM). Psychiatric symptoms were prevalent in LE and ANPRA subtypes, while weakness and gait instability/dystonia were predominant in the ADEM subtype. Higher peak CASE scores (odds ratio [OR] 1.846, 95% confidence interval [CI]: 1.163-2.930, p = 0.009) and initiating immunotherapy within 30 days (OR 0.210, 95% CI: 0.046-0.948, p = 0.042) were correlated with long-term outcomes. Receiver operating characteristic (ROC) analysis returned that the RAPID scores cutoff of 1.5 best discriminated the group with poor long-term outcomes (sensitivity 85.7%, specificity 56.9%).

INTERPRETATION

The ANPRA subtype exhibited poorer long-term outcomes compared to LE and ADEM subtypes, and early immunotherapy was crucial for improving long-term outcomes in antibody-negative AE. The use of RAPID scoring could aid in guiding clinical decision making.

Comparative Study of Paraneoplastic and Nonparaneoplastic Autoimmune Encephalitis With GABABR Antibodies

BACKGROUND AND OBJECTIVES

While patients with paraneoplastic autoimmune encephalitis (AE) with gamma-aminobutyric-acid B receptor antibodies (GABABR-AE) have poor functional outcomes and high mortality, the prognosis of nonparaneoplastic cases has not been well studied.

METHODS

Patients with GABABR-AE from the French and the Dutch Paraneoplastic Neurologic Syndromes Reference Centers databases were retrospectively included and their data collected; the neurologic outcomes of paraneoplastic and nonparaneoplastic cases were compared. Immunoglobulin G (IgG) isotyping and human leukocyte antigen (HLA) genotyping were performed in patients with available samples.

RESULTS

A total of 111 patients (44/111 [40%] women) were enrolled, including 84 of 111 (76%) paraneoplastic and 18 of 111 (16%) nonparaneoplastic cases (cancer status was undetermined for 9 patients). Patients presented with seizures (88/111 [79%]), cognitive impairment (54/111 [49%]), and/or behavioral disorders (34/111 [31%]), and 54 of 111 (50%) were admitted in intensive care unit (ICU). Nonparaneoplastic patients were significantly younger (median age 54 years [range 19-88] vs 67 years [range 50-85] for paraneoplastic cases, p < 0.001) and showed a different demographic distribution. Nonparaneoplastic patients more often had CSF pleocytosis (17/17 [100%] vs 58/78 [74%], p = 0.02), were almost never associated with KTCD16-abs (1/16 [6%] vs 61/70 [87%], p < 0.001), and were more frequently treated with second-line immunotherapy (11/18 [61%] vs 18/82 [22%], p = 0.003). However, no difference of IgG subclass or HLA association was observed, although sample size was small (10 and 26 patients, respectively). After treatment, neurologic outcome was favorable (mRS ≤2) for 13 of 16 (81%) nonparaneoplastic and 37 of 84 (48%) paraneoplastic cases (p = 0.03), while 3 of 18 (17%) and 42 of 83 (51%) patients had died at last follow-up (p = 0.008), respectively. Neurologic outcome no longer differed after adjustment for confounding factors but seemed to be negatively associated with increased age and ICU admission. A better survival was associated with nonparaneoplastic cases, a younger age, and the use of immunosuppressive drugs.

DISCUSSION

Nonparaneoplastic GABABR-AE involved younger patients without associated KCTD16-abs and carried better neurologic and vital prognoses than paraneoplastic GABABR-AE, which might be due to a more intensive treatment strategy. A better understanding of immunologic mechanisms underlying both forms is needed.

Autoimmune encephalitis: what the radiologist needs to know

Autoimmune encephalitis is a relatively novel nosological entity characterized by an immune-mediated damage of the central nervous system. While originally described as a paraneoplastic inflammatory phenomenon affecting limbic structures, numerous instances of non-paraneoplastic pathogenesis, as well as extra-limbic involvement, have been characterized. Given the wide spectrum of insidious clinical presentations ranging from cognitive impairment to psychiatric symptoms or seizures, it is crucial to raise awareness about this disease category. In fact, an early diagnosis can be dramatically beneficial for the prognosis both to achieve an early therapeutic intervention and to detect a potential underlying malignancy. In this scenario, the radiologist can be the first to pose the hypothesis of autoimmune encephalitis and refer the patient to a comprehensive diagnostic work-up - including clinical, serological, and neurophysiological assessments.In this article, we illustrate the main radiological characteristics of autoimmune encephalitis and its subtypes, including the typical limbic presentation, the features of extra-limbic involvement, and also peculiar imaging findings. In addition, we review the most relevant alternative diagnoses that should be considered, ranging from other encephalitides to neoplasms, vascular conditions, and post-seizure alterations. Finally, we discuss the most appropriate imaging diagnostic work-up, also proposing a suggested MRI protocol.

Brain fog in central disorders of hypersomnolence: a review

Brain fog is an undefined term describing a cluster of symptoms related to fatigue and impaired memory, attention, and concentration. Brain fog or brain fog-like symptoms have been reported in central disorders of hypersomnolence and in a range of seemingly unrelated disorders, including coronavirus disease 2019, major depressive disorder, multiple sclerosis, lupus, and celiac disease. This narrative review summarizes current evidence and proposes a consensus definition for brain fog. Brain fog is prevalent in narcolepsy and idiopathic hypersomnia, with more than three-quarters of patients with either disorder reporting this symptom in a registry study; it has also been reported as particularly difficult to treat in idiopathic hypersomnia. Studies directly evaluating brain fog are rare; tools for evaluating this symptom cluster typically are patient reports, with few objective measures validated in any disorder. Evaluating brain fog is further complicated by confounding symptoms, such as excessive daytime sleepiness, which is a hallmark of hypersomnolence disorders. No treatments specifically address brain fog. The paucity of literature, assessment tools, and medications for brain fog highlights the need for research leading to better disambiguation and treatment. Until a clear consensus definition is established, we propose brain fog in hypersomnia disorders be defined as a cognitive dysfunction that may or may not be linked with excessive sleepiness, related to an underlying neuronal dysfunction, which reduces concentration and impairs information processing, leading to a complaint of lack of clarity of mental thinking and awareness.

CITATION

Rosenberg R, Thorpy MJ, Doghramji K, Morse AM. Brain fog in central disorders of hypersomnolence: a review. J Clin Sleep Med. 2024;20(4):643-651.

Mapping the global research landscape and trends of autoimmune encephalitis: A bibliometric analysis

Background

Autoimmune encephalitis (AE) is a neuroautoimmune disease featured by the presence of antibodies targeting neuronal surface, synaptic, or intracellular antigens. An increasing number of articles on its clinical manifestations, treatments, and prognosis have appeared in recent years. The objectives of this study were to summarize this growing body of literature and provide an overview of hotspots and trends in AE research using bibliometric analysis.

Methods

We retrieved AE-related articles published between 1999 and 2022 from the Web of Science Core Collection. Using bibliometric websites and software, we analyzed the data of AE research, including details about countries, institutions, authors, references, journals, and keywords.

Results

We analyzed 3348 articles, with an average of 32.83 citations per article and an H-index of 141. The USA (1091, 32.587%), China (531, 15.860%), Germany (447, 13.351%), England (266, 7.945%), and Japan (213, 6.362%) had the greatest numbers of publications. The top five institutions by numbers of publications were Oxford (143, 4.271%), the Udice French Research Universities (135, 4.032%), the University of Pennsylvania (135, 4.032%), l'Institut National de la Sante de la Recherche Medicale Inserm (113, 3.375%), and the University of Barcelona (110, 3.286%). The most productive authors were J. Dalmau (98, 2.927%), A. Vincent (65, 2.479%), H. Pruess (64, 1.912%), C. G. Bien (43, 1.284%), and F. Graus (43, 1.284%). "autoimmune encephalitis" was the most frequently used keyword (430), followed by "antibodies" (420), "NMDA receptor encephalitis" (383), and "limbic encephalitis" (368). In recent years, research hotspots have focused on the diagnosis and immunotherapy of NMDAR encephalitis and on limbic encephalitis.

Conclusion

Developed Western countries have made significant contributions to this field. China has shown a steady increase in the number of publications in recent years, but the quality and influence of these articles warrant efforts at improvement. Future directions in AE research lie in two key areas: (i) the clinical manifestations, prevalence, and prognosis of AE (enabled by advances in diagnosis); and (ii) the efficacy and safety of targeted, individualized immunotherapy.

Overview of Paraneoplastic Autoantibody-Mediated Cognitive Impairment and Behavioral Changes: A Narrative Review

Cognitive dysfunction and behavioral change can be some of the manifestations of cancer, occurring as a part of paraneoplastic neurological syndrome, most commonly in small cell lung cancer. Paraneoplastic limbic encephalitis is the leading cause of cognitive disturbance and abnormal behavior in paraneoplastic syndromes, which is usually autoantibody-mediated. Autoantibodies are the main contributors to the development of cognitive dysfunction and behavioral change in cancer patients, with studies suggesting a higher liability for antibody-positive cancer patients to be affected. Anti-NMDAR and anti-AMPAR are antibodies targeted against surface antigens, manifesting predominantly as memory disturbance, abnormal behavior, psychiatric symptoms, and seizures. Other surface antigen-targeted antibodies include anti-GABA, anti-CASPR2, and anti-LGI1, which were shown to have cognitive function impairment and abnormal behavior as some of the main presentations, predominantly affecting memory. Cognitive deterioration and changes in behavior were also relatively common with some of the intracellular antigen-targeted antibodies, including anti-Hu, anti-SOX1, anti-PCA2, and anti-Zic2. Affected behavior and cognition, however, were reported less commonly in other paraneoplastic antibodies against intracellular antigens (anti-Yo, anti-GAD, anti-Ma2, anti-Ri, anti-CV2, and anti-KLHL11). Our article will provide a comprehensive review of the clinical manifestations of cognitive impairment and behavioral changes among cancer patients who develop paraneoplastic syndrome. Additionally, this review will discuss the role of specific paraneoplastic autoantibodies and the clinical spectrum linked to each separately.

A novel classification model based on cerebral 18F-FDG uptake pattern facilitates the diagnosis of acute/subacute seropositive autoimmune encephalitis

PURPOSE

To explore the intrinsic alteration of cerebral 18F-FDG metabolism in acute/subacute seropositive autoimmune encephalitis (AE) and to propose a universal classification model based on 18F-FDG metabolic patterns to predict AE.

METHODS

Cerebral 18F-FDG PET images of 42 acute/subacute seropositive AE patients and 45 healthy controls (HCs) were compared using voxelwise and region of interest (ROI)-based schemes. The mean standardized uptake value ratios (SUVRs) of 59 subregions according to a modified Automated Anatomical Labeling (AAL) atlas were compared using a t-test. Subjects were randomly divided into a training set (70%) and a testing set (30%). Logistic regression models were built based on the SUVRs and the models were evaluated by determining their predictive value in the training and testing sets.

RESULTS

The 18F-FDG uptake pattern in the AE group was characterized by increased SUVRs in the brainstem, cerebellum, basal ganglia, and temporal lobe, and decreased SUVRs in the occipital, and frontal regions with voxelwise analysis (false discovery rate [FDR] p<0.05). Utilizing ROI-based analysis, we identified 15 subareas that exhibited statistically significant changes in SUVRs among AE patients compared to HC (FDR p<0.05). Further, a logistic regression model incorporating SUVRs from the calcarine cortex, putamen, supramarginal gyrus, cerebelum_10, and hippocampus successfully enhanced the positive predictive value from 0.76 to 0.86 when compared to visual assessments. This model also demonstrated potent predictive ability, with AUC values of 0.94 and 0.91 observed for the training and testing sets, respectively.

CONCLUSIONS

During the acute/subacute stages of seropositive AE, alterations in SUVRs appear to be concentrated within physiologically significant regions, ultimately defining the general cerebral metabolic pattern. By incorporating these key regions into a new classification model, we have improved the overall diagnostic efficiency of AE.

Discrimination between leucine-rich glioma-inactivated 1 antibody encephalitis and gamma-aminobutyric acid B receptor antibody encephalitis based on ResNet18

This study aims to discriminate between leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis and gamma-aminobutyric acid B (GABAB) receptor antibody encephalitis using a convolutional neural network (CNN) model. A total of 81 patients were recruited for this study. ResNet18, VGG16, and ResNet50 were trained and tested separately using 3828 positron emission tomography image slices that contained the medial temporal lobe (MTL) or basal ganglia (BG). Leave-one-out cross-validation at the patient level was used to evaluate the CNN models. The receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) were generated to evaluate the CNN models. Based on the prediction results at slice level, a decision strategy was employed to evaluate the CNN models' performance at patient level. The ResNet18 model achieved the best performance at the slice (AUC = 0.86, accuracy = 80.28%) and patient levels (AUC = 0.98, accuracy = 96.30%). Specifically, at the slice level, 73.28% (1445/1972) of image slices with GABAB receptor antibody encephalitis and 87.72% (1628/1856) of image slices with LGI1 antibody encephalitis were accurately detected. At the patient level, 94.12% (16/17) of patients with GABAB receptor antibody encephalitis and 96.88% (62/64) of patients with LGI1 antibody encephalitis were accurately detected. Heatmaps of the image slices extracted using gradient-weighted class activation mapping indicated that the model focused on the MTL and BG for classification. In general, the ResNet18 model is a potential approach for discriminating between LGI1 and GABAB receptor antibody encephalitis. Metabolism in the MTL and BG is important for discriminating between these two encephalitis subtypes.

Case report: Coexistence of Labbe vein thrombosis and autoimmune encephalitis with two different antibodies

Anti-NMDA receptor encephalitis is an autoimmune encephalitis well- known to pediatric neurologists. The characteristic combination of symptoms and detection of NMDA receptor antibody can confirm the diagnosis. Most children respond well to immunosuppressive therapy. Anti-GABAB receptor encephalitis usually occurs in adult patients. Most patients present clinically with symptoms of limbic encephalitis. Cases in pediatric patients are rare. Cerebral venous thrombosis also has a very low incidence in children without underlying diseases. Patients usually present with headaches, convulsions, and focal deficits. Anticoagulants are the first choice treatment. We report a boy initially diagnosed with Labbe vein thrombosis and later tested positive for both NMDA and GABAB receptors. Anticoagulants did not relieve the boy's symptoms, and immunosuppressive therapy achieved good results. The antibody titers were significantly reduced or even turned negative. Although the Labbe vein was not recanalized at four months follow-up, the brain lesion was significantly absorbed. We learn from this case that a child can be inflicted with cerebral venous thrombosis and autoimmune encephalitis simultaneously. Child patients respond well to treatment.

Late-Onset Anti-GABAB Receptor Encephalitis: Clinical Characteristics and Outcomes Differing From Early-Onset Patients

BACKGROUND AND OBJECTIVES

Existing evidence indicates anti-GABA_B receptor encephalitis (GABA_BR-E) seems to occur more commonly later in life, yet the age-associated differences in clinical features and outcomes are not well determined. This study aims to explore the demographic, clinical characteristics, and prognostic differences between late-onset and early-onset GABA_BR-E and identify predictors of favorable long-term outcomes.

METHODS

This is an observational retrospective study conducted in 19 centers from China. Data from 62 patients with GABA_BR-E were compared between late-onset (aged 50 years or older) and early-onset (younger than 50 years) groups and between groups with favorable outcomes (modified Rankin scale (mRS) ≤ 2) and poor outcomes (mRS >2). Logistic regression analyses were applied to identify factors affecting long-term outcomes.

RESULTS

Forty-one (66.1%) patients experienced late-onset GABA_BR-E. A greater proportion of males, a higher mRS score at onset, higher frequencies of ICU admission and tumors, and a higher risk of death were demonstrated in the late-onset group than in the early-onset group. Compared with poor outcomes, patients with favorable outcomes had a younger onset age, a lower mRS score at onset, lower frequencies of ICU admission and tumors, and a greater proportion with immunotherapy maintenance for at least 6 months. On multivariate regression analysis, age at onset (OR, 0.849, 95% CI 0.739-0.974, p = 0.020) and the presence of underlying tumors (OR, 0.095, 95% CI 0.015-0.613, p = 0.013) were associated with poorer long-term outcomes, whereas immunotherapy maintenance for at least 6 months was associated with favorable outcomes (OR, 10.958, 95% CI 1.469-81.742, p = 0.020).

DISCUSSION

These results demonstrate the importance of risk stratification of GABA_BR-E according to age at onset. More attention should be paid to older patients especially with underlying tumors, and immunotherapy maintenance for at least 6 months is recommended to achieve a favorable outcome.

Autoimmune encephalitis : Part 1 (Epidemiology, Pathophysiology and Clinical spectrum)

Since the identification of anti-N-methyl-D-aspartate (NMDA) receptor antibodies about 15 years ago, many patients with rapidly progressing psychiatric symptoms, abnormal movements, seizures or unexplained coma, have been diagnosed with autoimmune encephalitis (AE). The symptom onset is often unspecific and might mimic psychiatric disease, but the later course is frequently characterized by severe disease, often requiring intensive care. Clinical and immunological criteria are helpful in identifying the patients, but no biomarkers exist to guide the clinician in therapy or predict outcome. While persons of all ages can be affected by AE, some types of AE affect more children and young adults and are more prevalent in women. This review will focus on encephalitides associated with neuronal cell-surface or synaptic antibodies, which can result in characteristic syndromes, and are often recognizable on clinical grounds. AE subtypes associated with antibodies against extracellular epitopes can occur with or without tumours. Because the antibodies bind and alter the function of the antigen, the effects are often reversible if immunotherapy is initiated, and the prognosis is favourable in most instances. The first part of this series will introduce the topic, provide an overview of current neuronal surface antibodies and how they present, describe the most common subtype, anti-NMDA receptor encephalitis, and discuss the difficulties in recognizing patients with underlying AE amongst patients with new onset psychiatric disorders.

Clinical characteristics and prognosis of anti-GABABR encephalitis: A single-center experience

The purpose of this study was to assess the demographic data, clinical manifestations, cerebrospinal fluid (CSF), hematology, brain magnetic resonance imaging, electroencephalograms, and therapy and prognosis related to anti-gamma-aminobutyric acid B (anti-GABABR) encephalitis. We retrospectively examined the demographic data, clinical manifestations, laboratory results, brain magnetic resonance imaging, electroencephalograms, and therapy and prognosis of 6 patients with anti-GABABR encephalitis. We used the clinical data of patients with anti-GABABR encephalitis admitted to the Department of Neurology of Mianyang Central Hospital obtained from January 2017 to September 2020. Six patients with anti-GABABR encephalitis were included. Generalized tonic-clonic seizure was the first clinical symptom in 5 patients, while 1 patient first showed behavior disorder. After the first clinical symptom attack, 2 patients developed a memory deficit, 4 cases showed cognitive decline, 3 cases showed behavior disorder, 1 patient developed status epilepticus and only 1 patient returned to normal. CSF testing indicated normal intracranial pressure in 5 patients and elevated pressure in only 1 patient. Additionally, the cerebrospinal fluid tests revealed slight leukocytosis in all patients and elevated protein levels in 5 patients. The anti-GABABR antibody was positive in both serum and CSF in all patients. Brain magnetic resonance imaging showed limbic system lesions in 4 patients. Long-term electroencephalograms revealed abnormal waves in half of the patients. All patients were treated with high dosages of methylprednisolone, which was combined with intravenous immunoglobulin in 2 patients; symptoms were improved in 4 patients, 1 patient showed no significant change and 1 patient with status epilepticus died of severe pneumonia during hospitalization. Epilepsy is the most common initial symptom in patients of anti-GABABR encephalitis. Many patients are also affected by tumors. Early immunotherapy can achieve excellent effects, the long-term prognosis is good for most patients.

Epilepsy, Immunity and Neuropsychiatric Disorders

Several studies have focused on the emerging role of immunity and inflammation in a wide range of neurological disorders. Autoimmune diseases involving central nervous system share well defined clinical features including epileptic seizures and additional neuropsychiatric symptoms, like cognitive and psychiatric disturbances. The growing evidence about the role of immunity in the pathophysiologic mechanisms underlying these conditions lead to the concept of autoimmune epilepsy. This relatively-new term has been introduced to highlight the etiological and prognostic implications of immunity in epileptogenesis. In this review, we aim to discuss the role of autoimmunity in epileptogenesis and its clinical, neurophysiological, neuroimaging and therapeutic implications. Moreover, we wish to address the close relationship between immunity and additional symptoms, particularly cognitive and psychiatric features, which deeply impact clinical outcomes in these patients. To assess these aspects, we first analyzed Rasmussen's encephalitis. Subsequently, we have covered autoimmune encephalitis, particularly those associated with autoantibodies against surface neuronal antigens, as these autoantibodies express a direct immune-mediated mechanism, different from those against intracellular antigens. Then, we discussed the connection between systemic immune disorders and neurological manifestations. This review aims to highlight the need to expand knowledge about the role of inflammation and autoimmunity in the pathophysiology of neurological disorders and the importance to early recognize these clinical entities. Indeed, early identification may result in faster recovery and a better prognosis.

Use of anti-seizure medications in different types of autoimmune encephalitis: A narrative review

Seizures are the main manifestation of the acute phase of autoimmune encephalitis (AE). Anti-seizure medications (ASMs) play an important role in controlling seizures in AE patients, but there is currently a lack of consensus regarding the selection, application, and discontinuation of ASMs. This narrative review focuses on the use of ASMs in patients with AE driven by different antibodies. The PubMed, Embase, and MEDLINE databases were searched up until 30 October 2022 using prespecified search terms. We identified 2,580 studies; 23 retrospective studies, 2 prospective studies and 9 case reports were evaluated based on our inclusion criteria. Anti-N-methyl-D-aspartic-acid-receptor (anti-NMDAR) encephalitis is the type of AE that responds best to ASMs, and long-term or combined use of ASMs may be not required in most patients with seizures; these results apply to both adults and children. Sodium channel blockers may be the best option for seizures in anti-leucine-rich-glioma-inactivated-1 (anti-LGI1) encephalitis, but patients with anti-LGI1 encephalitis are prone to side effects when using ASMs. Cell surface antibody-mediated AE patients are more likely to use ASMs for a long period than patients with intracellular antibody-mediated AE. Clinicians can score AE patients' clinical characteristics on a scale to identify those who may require long-or short-term use of ASMs in the early stage. This review provides some recommendations for the rational use of ASMs in encephalitis mediated by different antibodies with the aim of controlling seizures and avoiding overtreatment.

Cytokines/chemokines and soluble immune checkpoint molecules in anti-GABAB receptor encephalitis

BACKGROUND

Anti-gamma-aminobutyric-acid B receptor (anti-GABA_BR) encephalitis is a rare form of autoimmune limbic encephalitis (ALE) that is closely associated with tumor comorbidity. The purpose of this study is to identify the expressive pattern of cytokines/ chemokines and soluble immune checkpoint molecules (sICMs) in anti-GABA_BR encephalitis in order to evaluate the clinical condition and provide new treatment options.

METHODS

A total of 40 cytokines/chemokines and 10 sICMs in the serum of 10 patients with anti-GABA_BR encephalitis and eight controls were measured. The differentially expressed cytokines/chemokines and sICMs were selected to explore the correlations with disease prognosis, CSF routine and antibody titers.

RESULTS

Eight cytokines/chemokines were found to be more abundant in patients than in healthy donors (HDs), while 14 were found to be less abundant in patients. In terms of sICMs, patients' serum contained higher level of soluble ICOS and ICOSL but lower level of soluble CD86. Unfavorable prognosis was associated with high serum level of PDGFB, IL-17A, and soluble ICOSL but not with low levels of IL-4. Increased levels of IL-17A, CCL15, and soluble ICOS were found frequently in the patients with CSF-exclusive OCBs, while soluble ICOSL and CCL24 expression was lower in these patients. High levels of IL-1 F2 and TCA-3 were correlated with the presence of tumors in patients.

CONCLUSION

The majority of patients with anti- GABA_BR encephalitis had an unfavorable prognosis in one year of follow-up. Serum PDGFB, IL-17A, IL-4 and soluble ICOSL level were associated with the poor clinical outcomes in one-year follow up.

The diagnostic challenge of small cell lung cancer with anti-gamma-aminobutyric-acid B receptor encephalitis: a case report

Background

Anti-gamma-aminobutyric-acid B receptor (anti-GABA_BR) encephalitis is a rare type of encephalitis, with an incidence of only 5% in all autoimmune encephalitis (AE). A third of patients had pathologically confirmed small-cell lung cancer (SCLC). Early identification and treatment of tumors can improve the poor prognosis. Most patients attend hospital for the treatment of neurological disorders and rarely present with any respiratory symptoms, but suffer from an underlying tumor. Thus, early proper diagnosis is very important. In this article, we report a special case of a patient with anti-GABA_BR encephalitis with delayed SCLC pulmonary behavior, whose diagnosis prosses was tortuous and complicated.

Case Description

A 62-year-old man with a history of anti-GABA_BR encephalitis presented with respiratory symptoms. His chest computed tomography (CT) scan showed significant progression of right superior lobe consolidation. A bronchoscopy was performed with no histopathological result, but the microbiological examination of the bronchial lavage fluid showed Aspergillus niger infection. With antifungal therapy, the patient's respiratory symptoms were significantly relieved. Given the close relationship between SCLC and anti-GABA_BR encephalitis, we insisted to clarify the pulmonary lesions. The other three biopsies were performed successively, including lung biopsy, endobronchial ultrasonography (EBUS), and transbronchial needle aspiration (TBNA). SCLC was finally proven by pathology, and the patient received systemic chemotherapy.

Conclusions

SCLC is the most common pulmonary neuroendocrine tumor. It secretes onconeural antibodies and is closely associated with paraneoplastic neurologic syndromes (PNSs). Lung tumors, especially SCLC, should be a concern in patients presenting with AE or neurological symptoms, even if they have not any abnormal sign in respiratory system. The early diagnosis and intervention for underlying tumors will improve the clinical outcomes of patients significantly. Thus, the close follow-up is helpful and it is imperative to select and combine the most appropriate examinations for proper diagnosis.

An Unusual Case of Two Paraneoplastic Neurological Syndromes in a Patient With Lung Cancer

Paraneoplastic immune-mediated disorders have been well described in the literature. However, it is still relatively rare. The incidence has increased over the past decade due largely to the discovery of more autoantibodies. With a better understanding of the pathophysiology of different autoantibodies and clinical phenotypes, we are often able to diagnose clinically some specific paraneoplastic autoimmune neurological syndromes. We may also predict the response to treatment based on the autoantibody class. We are presenting a very unusual case of two completely different paraneoplastic syndromes with two different autoantibodies, gamma-aminobutyric acid-B (GABA_B) and collapsin response mediator protein 5 (CRMP5), in a patient with underlying small-cell lung cancer. We will discuss the differences in the two antibody syndromes, their significance, and their management.

Anti–Gamma Aminobutyric Acid B Autoimmune Encephalitis in an Indian Child with Early-Onset Seizures, Neurodegeneration, and Brain Calcification due to NRROS Variation: The First Reported Case Worldwide

A 1.5-year-old boy presented to us with a history of normal growth and developmental parameters until 6 months of age. However, at 7 months of age, he developed multiple types of seizures consisting initially of complex febrile seizures, followed by afebrile seizures. Multifocal clonic, generalized tonic–clonic, and myoclonic (multifocal and generalized) were the evolving seizure types. He had truncal hypotonia, but his appendicular hypotonia progressed to hypertonia over the next few months and further to decorticate posturing. Brain magnetic resonance imaging (MRI) showed generalized atrophy, predominantly frontotemporal, without any focal signal abnormalities or contrast enhancement. Computed tomography (CT) showed speckled calcification in subcortical white matter. Electroencephalogram showed bilateral frontotemporal epileptiform discharges with secondary generalization. His cerebrospinal fluid had normal cytology and biochemical results but was positive for anti–gamma aminobutyric acid B antibodies. Whole exome sequencing showed likely pathogenic, novel autosomal recessive homozygous variation of NRROS gene on chromosome 3 [c.1487G > A (p.Trp496Ter)], which impairs the functioning of anti-inflammatory cytokine transforming growth factor beta, resulting in a proinflammatory state within the central nervous system and thereby promoting autoimmune encephalitis. Parental Sanger sequencing validated the variation in both his parents. He was treated with both pulse methylprednisolone (30 mg/kg/day for 5 days) and intravenous immunoglobulin (2 g/kg), followed by slowly tapering of oral prednisolone and monthly intravenous immunoglobulin infusion (1 g/kg). There was significant reduction in seizure frequency and disappearance of epileptiform discharges from the electroencephalogram. However, the motor and cognitive improvement did not occur, and he had microcephaly and growth failure at the last follow-up. This is the 11th case report of neurodegeneration associated with NRROS gene variations, but the first report of autoimmune encephalitis being triggered by the variation in a child.

Herpes Simplex Encephalitis: Detection, Management, and Outcomes

The pathophysiology of herpes simplex encephalitis (HSE) is incompletely understood and proposed to be secondary to the retrograde transport of the herpes simplex virus type 1 (HSV-1) via the trigeminal and/or olfactory nerves to the central nervous system (CNS). In this case report, we present a 68-year-old female who presents to our emergency department after a fall. Upon initial admission, her neurological examination was benign, and a computer tomography (CT) scan of her brain showed a subdural hematoma for which she was treated conservatively. Day 4 of her hospitalization marked a rapid decline in her course of illness, beginning with confusion and hallucinations, progressing to subclinical seizures, and culminating in irreversible brain damage and palliative extubation on day 16 of hospitalization. This case report discusses our insight into the challenges of early diagnosis and treatment of herpes encephalitis and their impact on improving patient outcomes.

Heterogeneity and Functions of Tumor-Infiltrating Antibody Secreting Cells: Lessons from Breast, Ovarian, and Other Solid Cancers

Simple Summary

B cells are gaining increasing recognition as important contributors to the tumor microenvironment, influencing, positively or negatively, tumor growth, patient survival, and response to therapies. Antibody secreting cells (ASCs) constitute a variable fraction of tumor-infiltrating B cells in most solid tumors, and they produce tumor-specific antibodies that can drive distinct immune responses depending on their isotypes and specificities. In this review, we discuss the current knowledge of the heterogeneity of ASCs infiltrating solid tumors and how both their canonical and noncanonical functions shape antitumor immunity, with a special emphasis on breast and ovarian cancers.

Abstract

Neglected for a long time in cancer, B cells and ASCs have recently emerged as critical actors in the tumor microenvironment, with important roles in shaping the antitumor immune response. ASCs indeed exert a major influence on tumor growth, patient survival, and response to therapies. The mechanisms underlying their pro- vs. anti-tumor roles are beginning to be elucidated, revealing the contributions of their secreted antibodies as well as of their emerging noncanonical functions. Here, concentrating mostly on ovarian and breast cancers, we summarize the current knowledge on the heterogeneity of tumor-infiltrating ASCs, we discuss their possible local or systemic origin in relation to their immunoglobulin repertoire, and we review the different mechanisms by which antibody (Ab) subclasses and isoforms differentially impact tumor cells and anti-tumor immunity. We also discuss the emerging roles of cytokines and other immune modulators produced by ASCs in cancer. Finally, we propose strategies to manipulate the tumor ASC compartment to improve cancer therapies.

Clinical characteristics and prognosis of anti-γ-aminobutyric acid-B receptor encephalitis: A single-center, longitudinal study in China

Objective

Anti-γ-aminobutyric acid-B receptor (GABA_BR) encephalitis is a rare type of autoimmune encephalitis. There are only a few, small, published studies regarding prognosis, so prediction of prognosis is of limited accuracy. We identified 37 cases of anti-GABA_BR encephalitis in China. Here, we present these patients' clinical characteristics and long-term outcomes.

Methods

We collected and retrospectively analyzed the clinical data of 37 patients with anti-GABA_BR encephalitis from Beijing Fengtai You'anmen Hospital.

Results

The study cohort comprised 37 patients of anti-GABA_BR encephalitis of median age 61 years (range: 11–77), 28 of whom were male. The main clinical manifestations were epilepsy (91.9%, 34/37), psychiatric disorders (94.6%, 35/37) and cognitive impairment (97.3%, 36/37). Tumors were identified in 18 (48.6%) patients. First-line immunotherapy was administered to 34 patients, 31 of whom (90.6%) responded favorably. During a median follow-up of 18 months (range: 1–72 months), 21 patients had good outcomes [Modified Ranking Scale (mRS ≤2)], 16 (43.2%) died (mRS 6), and 7 (18.9%) relapsed. Age (P = 0.005), disturbance of consciousness (P = 0.018), admission to the Neurology Intensive Care Unit (P = 0.003), mechanical ventilation (P = 0.009), more numerous clinical manifestations (P = 0.008), comorbid malignancy (P = 0.008), multiple anti-neuronal antibodies (P = 0.029), and hyponatremia (P = 0.023) differed significantly between patients with good outcomes (mRS 0–2) and those with poor outcomes (mRS 3–6).

Conclusion

Men aged 50–70 years accounted for most of the patients with anti-GABA_BR encephalitis in our case series. The main clinical manifestations were epilepsy and neuropsychiatric dysfunction. The participants often had concomitant lung cancer, particularly small-cell lung cancer. Patients with lung tumors and/or serious manifestations usually had a poor prognosis with high mortality. Early identification and treatment of tumors improved the poor prognosis to some extent.

Postvaccinal GABA-B receptor antibody encephalitis after ChAdOx1 nCoV-19 vaccination

Several cases of autoimmune encephalitis have been reported after ChAdOx1 nCoV-19 (AZD1222) vaccination. We encountered a male patient who presented with generalized tonic-clonic seizures, cognitive decline, and gait disturbance that occurred suddenly after the second dose of the ChAdOx1 nCoV-19 vaccine. Clinical presentation and magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) test results were compatible with limbic encephalitis. Synaptic autoantibody tests confirmed serum and CSF GABA B receptor antibodies were present. The patient was treated with immunotherapy with intravenous immunoglobulin and rituximab. This GABA-B receptor antibody encephalitis case occurred presumably due to transient autoantibody production following vaccine administration.

Coexistence of anti-SOX1 and anti-GABAB receptor antibodies with paraneoplastic limbic encephalitis presenting with seizures and memory impairment in small cell lung cancer: A case report

Purpose

Paraneoplastic neurological syndromes associated with autoantibodies are rare diseases that cause abnormal manifestations of the nervous system. Early diagnosis of paraneoplastic neurological syndromes paves the way for prompt and efficient therapy.

Case report

we reported a 56-year-old man presenting with seizures and rapidly progressive cognitive impairment diagnosed as paraneoplastic limbic encephalitis (PLE) with anti-SRY-like high-mobility group box-1 (SOX-1) and anti-γ-aminobutyric acid B (GABAB) receptor antibodies and finally confirmed by biopsy as small cell lung cancer (SCLC). At the first admission, brain magnetic resonance imaging (MRI) showed no abnormal signal in bilateral hippocampal regions and no abnormal enhancement of enhanced scan. The serum anti-GABAB receptor antibody was 1:100 and was diagnosed as autoimmune encephalitis (AE). The computed tomography (CT) scans of the chest showed no obvious tumor signs for the first time. Although positron emission tomography-computed tomography (PET-CT) revealed hypermetabolism in the para mid-esophageal, the patient and his family declined to undertake a biopsy. The patient improved after receiving immunoglobulin, antiepileptic therapy, and intravenous methylprednisolone (IVMP) pulse treatment. However, after 4 months, the symptoms reappeared. Brain MRI revealed abnormal signals in the hippocampal regions. Reexamination of the cerebral fluid revealed anti-GABAB receptor and anti-SOX-1 antibodies, which contributed to the diagnosis of PLE. SCLC was found in a para mid-esophageal pathological biopsy. Antiepileptic medications and immunoglobulin were used to treat the patient, and the symptoms were under control.

Conclusion

Our findings increase the awareness that patients with limbic encephalitis with cognitive dysfunction and epileptic seizures should be enhanced to detect latent malignancy. Our case also highlights the importance of anti-SOX1 antibodies in the detection of underlying neoplasm, particularly SCLC. Our findings raise awareness of the cognitive impairment seen by patients with limbic encephalitis.

Psychiatric manifestations of autoimmune encephalitis

Autoimmune encephalitis is increasingly recognized as a cause of psychiatric symptoms. A wide spectrum of psychiatric manifestations have been described which may precede, follow or occur independently of neurologic features. Patients typically respond to immunotherapy, however diagnosis is challenging due to phenotypic heterogeneity. The aim of this review is to provide an overview of the psychiatric features associated with encephalitis mediated by autoantibodies targeting neuronal cell-surface antigens and describe indicators of potential immunopathology underlying psychiatric manifestations.

Case Report: Anti-GABAA Receptor Encephalitis in a Dog

Autoantibodies against neurotransmitter receptors detected in cerebrospinal fluid (CSF) and serum are increasingly recognized in people with human autoimmune encephalitis causing severe neurological deficits, such as seizures and behavioral abnormalities. This case report describes the first encephalitis associated with antibodies against the γ-aminobutyric acid-A receptor (GABA_AR) in a dog. A young male intact Cavalier King Charles Spaniel was presented with recent onset of initial multiple generalized tonic-clonic seizures progressing into a status epilepticus. Interictally, he showed alternating stupor and hyperexcitability, ataxia, pleurothotonus and circling behavior to the left side. Magnetic resonance imaging (MRI) of the brain showed breed-specific anatomical abnormalities. Standard CSF analysis was unremarkable. Despite treatment with multiple antiseizure medications (ASMs) seizures and behavior abnormalities sustained. Immunotherapy with dexamethasone was started on the fifth day after disease manifestation. This led to rapid improvement of clinical signs. An extensive antibody search in CSF and serum demonstrated a neuropil staining pattern on a tissue-based assay compatible with GABA_AR antibodies. The diagnosis was confirmed by binding of serum and CSF antibodies to GABA_AR transfected Human Embryonic Kidney cells. The serum titer was 1:320, the CSF titer 1:2. At the control visit 4.5 weeks after start of immunotherapy, the dog was clinically normal. The GABA_AR antibody titer in serum had strongly decreased. The antibodies were no longer detectable in CSF. Based on clinical presentation and testing for GABA_AR binding antibodies, this describes the first veterinary patient with an anti-GABA_AR encephalitis with a good outcome following ASM and corticosteroid treatment.

18 F-fluorodeoxy-glucose positron emission tomography pattern and prognostic predictors in patients with anti-GABAB receptor encephalitis

Aims

To identify the metabolic pattern and prognostic predictors in anti‐gamma‐aminobutyric‐acid B (GABAB) receptor encephalitis using ¹⁸F‐fluorodeoxy‐glucose positron emission tomography (¹⁸F‐FDG‐PET).

Methods

Twenty‐one patients diagnosed anti‐GABAB receptor encephalitis who underwent ¹⁸F‐FDG‐PET at first hospitalization were retrospectively reviewed. ¹⁸F‐FDG‐PET images were analyzed in comparison with controls. Further group comparisons of ¹⁸F‐FDG‐PET data were carried out between prognostic subgroups.

Results

¹⁸F‐FDG‐PET was abnormal in 81% patients with anti‐GABAB receptor encephalitis and was more sensitive than MRI (81% vs. 42.9%, p = 0.025). Alter limbic lobe glucose metabolism (mostly hypermetabolism) was observed in 14 patients (66.7%), of whom 10 (10/14, 71.4%) demonstrated hypermetabolism in the medial temporal lobe (MTL). Group analysis also confirmed MTL hypermetabolism in association with relative frontal and parietal hypometabolism was a general metabolic pattern. After a median follow‐up of 33 months, the group comparisons revealed that patients with poor outcome demonstrated increased metabolism in the MTL compared to those with good outcome.

Conclusion

¹⁸F‐FDG‐PET may be more sensitive than MRI in the early diagnosis of anti‐GABAB receptor encephalitis. MTL hypermetabolism was associated with relative frontal or parietal hypometabolism and may serve as a prognostic biomarker in anti‐GABAB receptor encephalitis.

GABAB Receptors and Cognitive Processing in Health and Disease

GABA_B receptors are implicated in numerous central nervous system-based behaviours and mechanisms, including cognitive processing in preclinical animal models. Homeostatic changes in the expression and function of these receptors across brain structures have been found to affect cognitive processing. Numerous preclinical studies have focused on the role of GABA_B receptors in learning, memory and cognition per se with some interesting, although sometimes contradictory, findings. The majority of the existing clinical literature focuses on alterations in GABA_B receptor function in conditions and disorders whose main symptomatology includes deficits in cognitive processing. The aim of this chapter is to delineate the role of GABA_B receptors in cognitive processes in health and disease of animal models and human clinical populations. More specifically, this review aims to present literature on the role of GABA_B receptors in animal models with cognitive deficits, especially those of learning and memory. Further, it aims to capture the progress and advances of research studies on the effects of GABA_B receptor compounds in neurodevelopmental and neurodegenerative conditions with cognitive dysfunctions. The neurodevelopmental conditions covered include autism spectrum disorders, fragile X syndrome and Down's syndrome and the neurodegenerative conditions discussed are Alzheimer's disease, epilepsy and autoimmune anti-GABA_B encephalitis. Although some findings are contradictory, results indicate a possible therapeutic role of GABA_B receptor compounds for the treatment of cognitive dysfunction and learning/memory impairments for some of these conditions, especially in neurodegeneration. Moreover, future research efforts should aim to develop selective GABA_B receptor compounds with minimal, if any, side effects.

Autoimmune Limbic Encephalitis: A Review of Clinicoradiological Features and the Challenges of Diagnosis

Limbic encephalitis is an autoimmune cause of encephalitis. In addition to the usual symptoms of encephalitis such as altered consciousness, fever, and focal neurological deficits, limbic encephalitis can present with neuropsychiatric manifestations and seizures. Making a formal diagnosis involves a difficult and prolonged workup phase. The purpose of this review is to help readers delineate limbic encephalitis from other illnesses. This is done by presenting a spectrum of potential organic differential diagnoses and pertinent findings that distinguish them from limbic encephalitis. Instead of presenting a variety of psychiatric differential diagnoses, the authors present a review of psychiatric manifestations known to be associated with limbic encephalitis, as naturally, any psychiatric disorder could be a potential comorbid disease.

Sleep Disturbances Associated with Neurological Autoimmunity

Associations between sleep disorders and neurological autoimmunity have been notably expanding recently. Potential immune-mediated etiopathogenesis has been proposed for various sleep disorders including narcolepsy, Kleine-Levin syndrome, and Morvan syndrome. Sleep manifestations are also common in various autoimmune neurological syndromes, but may be underestimated as overriding presenting (and potentially dangerous) neurological symptoms often require more urgent attention. Even so, sleep dysfunction has been described with various neural-specific antibody biomarkers, including IgLON5; leucine-rich, glioma-inactivated protein 1 (LGI1); contactin-associated protein 2 (CASPR2); N-methyl-D-aspartate (NMDA)-receptor; Ma2; dipeptidyl-peptidase-like protein-6 (DPPX); alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R); anti-neuronal nuclear antibody type-1 (ANNA-1, i.e., Hu); anti-neuronal nuclear antibody type-2 (ANNA-2, i.e., Ri); gamma-aminobutyric acid (GABA)-B-receptor (GABA-B-R); metabotropic glutamate receptor 5 (mGluR5); and aquaporin-4 (AQP-4). Given potentially distinctive findings, it is possible that sleep testing could potentially provide objective biomarkers (polysomnography, quantitative muscle activity during REM sleep, cerebrospinal fluid hypocretin-1) to support an autoimmune diagnosis, monitor therapeutic response, or disease progression/relapse. However, more comprehensive characterization of sleep manifestations is needed to better understand the underlying sleep disruption with neurological autoimmunity.

Anti-LGI1, anti-GABABR, and Anti-CASPR2 encephalitides in Asia: A systematic review

AIM

We aim to review the literature to collate and describe features of encephalitides arising from autoantibodies against leucine-rich glioma-inactivated 1 (LGI1), gamma aminobutyric acid receptor (GABABR), and contactin-associated protein-like 2 (CASPR2) in Asian populations and compare them with findings of Western studies.

METHODS

Peer-reviewed articles published till 24 May 2020 were searched, and original, full-text studies from Asia with serum/CSF antibody-based diagnosis and at least 2 patients were selected. Twenty-four studies with 263 patients (139 anti-LGI1, 114 anti-GAGABR, and 10 anti-CASPR2) were included. Data were pooled to produce descriptive information on demographics, clinical characteristics, diagnostics, treatments, and outcome.

RESULTS

The mean age was 54.2 (anti-LGI1), 55.2 (anti-GABABR), and 47.7 years (anti-CASPR2), with an overall male predominance of 62.0%. Commonest clinical features across all types were seizures (87.5%), memory deficits (80.7%), psychiatric disturbances (75.9%), and altered consciousness (52.9%). Four anti-LGI1, 40 anti-GABABR, and 1 anti-CASPR2 patients had tumors. CSF, MRI, and EEG were abnormal in 33.3%, 54.1%, and 75% patients in anti-LGI1; 60.0%, 49.6%, and 85.7% in anti-GABABR; and 50%, 44.4%, and 100% in anti-CASPR2 patients, respectively. 95.6% patients received first-line therapy alone (steroids/IVIG/Plasma therapy), and 4.4% received second-line therapy (rituximab/cyclophosphamide). 91.7%, 63.6%, and 70% of patients had favorable outcomes (modified Rankin Score 0-2) with mortality rates at 2.5%, 23.2%, and 0% in the three types, respectively.

CONCLUSION

Our findings suggest that these disorders present in Asian patients at a relatively young age often with features of seizures, memory deficits, and psychiatric disturbances and usually demonstrate a favorable clinical outcome.

Comparisons Between Infectious and Autoimmune Encephalitis: Clinical Signs, Biochemistry, Blood Counts, and Imaging Findings

OBJECTIVE

Infectious encephalitis (IE) and autoimmune encephalitis (AE) are symptomatically similar in clinic, however essentially different in pathogenesis. Therefore, the objective of this study was to identify specific features to distinguish the two types of encephalitis for early effective diagnosis and treatments through a comparative analysis.

METHODS

Fifty-nine IE patients and 36 AE patients were enrolled. The patients with IE were divided into viral encephalitis (VE) and bacterial encephalitis (BE) according to the pathogens in cerebrospinal fluid (CSF). Patients with AE were categorized by with or without neural autoantibodies (NAAb). We further divided patients with NAAb into those with neural cell-surface antibodies (NSAbs) or intracellular antibodies (Abs). Clinical features, laboratory data, and imaging findings were compared between AE, IE, and subgroups.

RESULTS

Memory deficits, involuntary movement, and seizures were relatively more commonly presenting symptoms in AE patients (p < 0.05). The positive rate of Pandy test was higher in IE patients (p = 0.007). Decreased leukocyte, erythrocyte, and platelet counts in blood were found in IE patients (p < 0.05). Lower serum calcium level was found in VE compared to BE (p = 0.027). Meanwhile, higher serum calcium level was found in patients with NSAbs compared with intracellular Abs (p = 0.034). However, higher levels of LDH in CSF were found in patients with intracellular Abs (p = 0.009). In magnetic resonance imaging, hippocampus lesions were more commonly present in patients with AE (p = 0.042). Compared with AE patients, more IE patients displayed the background electroencephalogram rhythm of slow-frequency delta (p = 0.013).

CONCLUSION

Involuntary movement and memory deficits were more specifically present in AE patients. CSF Pandy, blood routine test and hippocampus lesions detections were potential markers for distinguishing AE and IE. Further, CSF LDH, and serum calcium levels were potentially useful to distinguish subgroups of encephalitis.