Subgroup comparison according to clinical phenotype and serostatus in autoimmune encephalitis: a multicenter retrospective study

Human stem cell-derived neurons and astrocytes to detect novel auto-reactive IgG response in immune-mediated neurological diseases

Background and objectives

Up to 46% of patients with presumed autoimmune limbic encephalitis are seronegative for all currently known central nervous system (CNS) antigens. We developed a cell-based assay (CBA) to screen for novel neural antibodies in serum and cerebrospinal fluid (CSF) using neurons and astrocytes derived from human-induced pluripotent stem cells (hiPSCs).

Methods

Human iPSC-derived astrocytes or neurons were incubated with serum/CSF from 99 patients [42 with inflammatory neurological diseases (IND) and 57 with non-IND (NIND)]. The IND group included 11 patients with previously established neural antibodies, six with seronegative neuromyelitis optica spectrum disorder (NMOSD), 12 with suspected autoimmune encephalitis/paraneoplastic syndrome (AIE/PNS), and 13 with other IND (OIND). IgG binding to fixed CNS cells was detected using fluorescently-labeled antibodies and analyzed through automated fluorescence measures. IgG neuronal/astrocyte reactivity was further analyzed by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were used as CNS-irrelevant control target cells. Reactivity profile was defined as positive using a Robust regression and Outlier removal test with a false discovery rate at 10% following each individual readout.

Results

Using our CBA, we detected antibodies recognizing hiPSC-derived neural cells in 19/99 subjects. Antibodies bound specifically to astrocytes in nine cases, to neurons in eight cases, and to both cell types in two cases, as confirmed by microscopy single-cell analyses. Highlighting the significance of our comprehensive 96-well CBA assay, neural-specific antibody binding was more frequent in IND (15 of 42) than in NIND patients (4 of 57) (Fisher's exact test, p = 0.0005). Two of four AQP4+ NMO and four of seven definite AIE/PNS with intracellular-reactive antibodies [1 GFAP astrocytopathy, 2 Hu+, 1 Ri+ AIE/PNS)], as identified in diagnostic laboratories, were also positive with our CBA. Most interestingly, we showed antibody-reactivity in two of six seronegative NMOSD, six of 12 probable AIE/PNS, and one of 13 OIND. Flow cytometry using hiPSC-derived CNS cells or PBMC-detected antibody binding in 13 versus zero patients, respectively, establishing the specificity of the detected antibodies for neural tissue.

Conclusion

Our unique hiPSC-based CBA allows for the testing of novel neuron-/astrocyte-reactive antibodies in patients with suspected immune-mediated neurological syndromes, and negative testing in established routine laboratories, opening new perspectives in establishing a diagnosis of such complex diseases.

Pediatric Autoimmune Encephalitis: A Nationwide Study in Latvia

BACKGROUND

 Autoimmune encephalitis (AE) is the third most common encephalitis in children. Diagnosis can be challenging due to overlapping and diverse clinical presentations as well as various investigation results. This study aims to characterize the clinical, diagnostic features, as well as treatment and outcomes of AE in children and determine the incidence of pediatric AE in Latvia.

METHODS

 The study was conducted at the Children's Clinical University Hospital in Riga. The study participants were patients under the age of 18 years diagnosed with AE from 2014 to 2022. Data regarding clinical characteristics, investigation findings, treatment strategy, and outcomes were retrospectively collected from the medical history data system.

RESULTS

 We included 18 pediatric patients diagnosed with AE. The mean incidence of pediatric AE in Latvia was 0.56 per 100,000 children. Most patients (66.6%) had seronegative AE. In the seropositive group, the most common was anti-methyl-D-aspartate receptor AE, with two patients having other antibodies. The most prevalent clinical features were personality change, cognitive impairment, autonomic dysfunction, and movement disorders. The majority of patients (58.8%) received first-line treatment only. More than half (55.6%) of our AE patient group had long-term sequelae.

CONCLUSIONS

 Our study shows that the pediatric AE incidence in Latvia is similar to what has been previously reported in other studies. A relatively high proportion of seronegative AE was present in our cohort, indicating that awareness of possible misdiagnosis should be raised. Further research is needed to better understand the underlying mechanisms, characterize clinical features, and determine the treatment of choice in different situations to improve long-term outcomes.

The clinical and predictive value of 18F-FDG PET/CT metabolic patterns in a clinical Chinese cohort with autoimmune encephalitis

AIMS

To investigate the diagnostic and predictive role of 18F-FDG PET/CT in patients with autoimmune encephalitis (AE) as a whole group.

METHODS

Thrty-five patients (20 females and 15 males) with AE were recruited. A voxel-to-voxel semi-quantitative analysis based on SPM12 was used to analyze 18F-FDG PET/CT imaging data compared to healthy controls. Further comparison was made in different prognostic groups categorized by modified Rankin Scale (mRS).

RESULTS

In total, 24 patients (68.6%) were tested positive neuronal antibodies in serum and/or CSF. Psychiatric symptoms and seizure attacks were major clinical symptoms. In the acute stage, 13 patients (37.1%) demonstrated abnormal brain MRI results, while 33 (94.3%) presented abnormal metabolism patterns. 18F-FDG PET/CT was more sensitive than MRI (p < 0.05). Patients with AE mainly presented mixed metabolism patterns compared to the matched controls, demonstrating hypermetabolism mainly in the cerebellum, BG, MTL, brainstem, insula, middle frontal gyrus, and relatively hypometabolism in the frontal cortex, occipital cortex, temporal gyrus, right parietal gyrus, left cingulate gyrus (p < 0.05, FWE corrected). After a median follow-up of 26 months, the multivariable analysis identified a decreased level of consciousness as an independent risk factor associated with poor outcome of AE (HR = 3.591, p = 0.016). Meanwhile, decreased metabolism of right superior frontal gyrus along with increased metabolism of the middle and upper brainstem was more evident in patients with poor outcome (p < 0.001, uncorrected).

CONCLUSION

18F-FDG PET/CT was more sensitive than MRI to detect neuroimaging abnormalities of AE. A mixed metabolic pattern, characterized by large areas of cortical hypometabolism with focal hypermetabolism was a general metabolic pattern. Decreased metabolism of right superior frontal gyrus with increased metabolism of the middle and upper brainstem may predict poor long-term prognosis of AE.

Steroid-Responsive Parkinsonism and Encephalopathy: A Case Report

We describe a patient who presented with rapidly progressive parkinsonism and encephalopathy and was diagnosed with seronegative autoimmune encephalitis (AE). Subacute parkinsonism as a manifestation of seronegative AE is uncommon with only a handful of similar cases published in literature. A 71-year-old man presented with severe flu like symptoms, rapidly progressive cognitive decline and was found to have parkinsonian features on examination. Initial brain magnetic resonance imaging (MRI) was unremarkable however, cerebrospinal fluid (CSF) analysis revealed a lymphocytic pleocytosis and elevated protein level. Thorough searches for neural antibodies and infectious pathogens were negative. His symptoms fluctuated initially but markedly improved within days of starting prednisone and dramatically worsened after prednisone was tapered off. His CSF pleocytosis also improved on prednisone. Relapses again resolved with resumption of prednisone. The scope of autoimmune neurology Is constantly evolving, and physicians should be aware of the diverse and heterogenous clinical presentations of autoimmune encephalitis. We aim to emphasize the importance of ruling out autoimmune encephalitis in patients presenting with acute or subacute parkinsonism. This case additionally reinforces that negative antibody tests do not exclude the diagnosis of AE.

Paraneoplastic encephalitis

The first reports of encephalitis associated with cancer date to the 1960s and were characterized by clinical and pathologic involvement of limbic areas. This specific association was called limbic encephalitis (LE). The subsequent discovery of several "onconeural" antibodies (Abs), i.e., Abs targeting an antigen shared by neurons and tumor cells, supported the hypothesis of an autoimmune paraneoplastic etiology of LE and other forms of rapidly progressive encephalopathy. Over the past 20 years, similar clinical pictures with different clinical courses have been described in association with novel Abs-binding neuronal membrane proteins and proved to be pathogenic. The most well-known encephalitis in this group was described in 2007 as an association of a complex neuro-psychiatric syndrome, N-methyl-d-aspartate (NMDA) receptor-Abs, and ovarian teratoma in young women. Later on, nonparaneoplastic cases of NMDA receptor encephalitis were also described. Since then, the historical concept of LE and Ab associated encephalitis has changed. Some of these occur in fact more commonly in the absence of a malignancy (e.g., anti-LG1 Abs). Lastly, seronegative cases were also described. The term paraneoplastic encephalitis nowadays encompasses different syndromes that may be triggered by occult tumors.

General features, pathogenesis, and laboratory diagnostics of autoimmune encephalitis

Autoimmune encephalitis (AE) is a group of inflammatory conditions that can associate with the presence of antibodies directed to neuronal intracellular, or cell surface antigens. These disorders are increasingly recognized as an important differential diagnosis of infectious encephalitis and of other common neuropsychiatric conditions. Autoantibody diagnostics plays a pivotal role for accurate diagnosis of AE, which is of utmost importance for the prompt recognition and early treatment. Several AE subgroups can be identified, either according to the prominent clinical phenotype, presence of a concomitant tumor, or type of neuronal autoantibody, and recent diagnostic criteria have provided important insights into AE classification. Antibodies to neuronal intracellular antigens typically associate with paraneoplastic neurological syndromes and poor prognosis, whereas antibodies to synaptic/neuronal cell surface antigens characterize many AE subtypes that associate with tumors less frequently, and that are often immunotherapy-responsive. In addition to the general features of AE, we review current knowledge on the pathogenic mechanisms underlying these disorders, focusing mainly on the potential role of neuronal antibodies in the most frequent conditions, and highlight current theories and controversies. Then, we dissect the crucial aspects of the laboratory diagnostics of neuronal antibodies, which represents an actual challenge for both pathologists and neurologists. Indeed, this diagnostics entails technical difficulties, along with particularly interesting novel features and pitfalls. The novelties especially apply to the wide range of assays used, including specific tissue-based and cell-based assays. These assays can be developed in-house, usually in specialized laboratories, or are commercially available. They are widely used in clinical immunology and in clinical chemistry laboratories, with relevant differences in analytic performance. Indeed, several data indicate that in-house assays could perform better than commercial kits, notwithstanding that the former are based on non-standardized protocols. Moreover, they need expertise and laboratory facilities usually unavailable in clinical chemistry laboratories. Together with the data of the literature, we critically evaluate the analytical performance of the in-house vs commercial kit-based approach. Finally, we propose an algorithm aimed at integrating the present strategies of the laboratory diagnostics in AE for the best clinical management of patients with these disorders.

Survival Analysis of Immunotherapy Effects on Relapse Rate in Pediatric and Adult Autoimmune Encephalitis

BACKGROUND AND OBJECTIVES

Prior observational studies for autoimmune encephalitis (AE) have mostly focused on outcomes after acute immunotherapies with better outcomes associated with earlier immunotherapy use. However, the impact of long-term immunotherapy and its association with clinical relapse is not well known.

METHODS

We conducted a retrospective study of consecutive patients meeting published clinical criteria for AE evaluated at UC San Diego and Rady Children's Hospital from January 2007 to November 2021. Survival analysis and Cox multivariable regression models were used to evaluate relapse risk using rituximab exposure as a time-dependent variable. Pooled and age-stratified analyses were performed.

RESULTS

A total of 204 pediatric and 380 adult participants were screened of which 30 pediatric and 75 adult participants were included. The most common antibody subtype in both cohorts was anti-NMDA receptor (76% in pediatric, 34% in adult). Relapses occurred in 31% of pediatric antibody-positive, 40% of adult antibody-positive, and 20% of adult antibody-negative cases. Times to first relapse (TTFR) were 10.6 ± 7.4 months (pediatric antibody-positive), 13.1 ± 24.5 months (adult antibody-positive), and 6.9 ± 3.8 months (adult antibody-negative). Rituximab was the most common second-line immunotherapy used. Combining pediatric and adult data, rituximab use was associated with a 71% lower hazard for time to first relapse (hazard ratio [HR] 0.29, 95% CI 0.09-0.85) and 51% lower hazard for recurring relapses (HR 0.49, 95% CI 0.9-1.26). The HR for TTFR with rituximab use in children was 0.30 (95% CI 0.05-1.69), 0.29 (95% CI 0.07-1.29) in adults, 0.32 in non-NMDA antibody-positive encephalitis (95% CI 0.07-1.39), and 0.42 (95% CI 0.07-2.67) for anti-NMDAR.

DISCUSSION

Relapses are common in pediatric and adult patients with AE, although less frequently in anti-NMDARE. Using a rigorous survival model, we demonstrate a substantial benefit of rituximab use for reducing relapse rates in AE, especially for the adult population.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that rituximab is associated with a lower hazard to relapse in patients with AE.

Predictive value of the neutrophil-to-lymphocyte ratio for treatment response in patients diagnosed with definite or probable autoimmune encephalitis/encephalopathy

Introduction

Autoimmune encephalitis/encephalopathy (AE) is a complex and heterogeneous disease, making it difficult to predict the prognosis. The neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential prognostic tool, but its usefulness remains a matter of debate. This study aimed to explore prognostic factors in cases of clinically definite or probable AE, including those with autoantibody-negative, or unknown status.

Methods

Data on patients diagnosed with definite or probable AE, including those with autoantibody-negative, or unknown status, were retrospectively collected from the admission records of our department between January 2013 and December 2022. These patients were then categorized into either a good- or poor-response group, based on their short-term treatment response. Clinical characteristics, auxiliary examinations, and treatments were compared between the two groups. A multivariable logistic regression model was constructed to identify independent predictors of poor short-term treatment response by Akaike information criterion backward stepwise method.

Results

A total of 31 patients were included in the final analysis, with 18 of them included in the poor-response group. In the univariable analysis, the poor-response group had a higher proportion of patients with a modified Rankin Scale (mRS) high score upon admission, female, epileptic seizures, or NLRs of 3.93 or higher than the good-response group (all p < 0.10). Furthermore, the multivariable logistic regression analysis revealed that the mRS score upon admission [OR: 5.51, 95% confidence intervals (CI): 1.29-23.50, p = 0.02], epileptic seizures (OR: 10.01, 95% CI: 1.16-86.66, p = 0.04), and NLRs of 3.93 or higher (OR: 11.37, 95% CI: 1.12-114.68, p = 0.04) were significantly associated with poor short-term treatment response.

Conclusion

The NLR may play a supplementary role in predicting the short-term treatment response in patients diagnosed with definite or probable AE, including those with autoantibody-negative, or unknown status.

Diagnostic criteria for autoimmune encephalitis: utility and pitfalls for antibody-negative disease

Increased awareness of autoimmune encephalitis has led to two unintended consequences: a high frequency of misdiagnoses and the inappropriate use of diagnostic criteria for antibody-negative disease. Misdiagnoses typically occur for three reasons: first, non-adherence to reported clinical requirements for considering a disorder as possible autoimmune encephalitis; second, inadequate assessment of inflammatory changes in brain MRI and CSF; and third, absent or limited use of brain tissue assays along with use of cell-based assays that include only a narrow range of antigens. For diagnosis of possible autoimmune encephalitis and probable antibody-negative autoimmune encephalitis, clinicians should adhere to published criteria for adults and children, focusing particularly on exclusion of alternative disorders. Moreover, for diagnosis of probable antibody-negative autoimmune encephalitis, the absence of neural antibodies in CSF and serum should be well substantiated. Neural antibody testing should use tissue assays along with cell-based assays that include a broad range of antigens. Live neuronal studies in specialised centres can assist in resolving inconsistencies with respect to syndrome-antibody associations. Accurate diagnosis of probable antibody-negative autoimmune encephalitis will identify patients with similar syndromes and biomarkers, which will provide homogeneous populations for future assessments of treatment response and outcome.

Therapy response in seronegative versus seropositive autoimmune encephalitis

Background

Autoimmune encephalitis (AE) might be seropositive or seronegative, depending on whether antibodies targeting well-characterized neuronal antigens can be detected or not. Since data on treatment efficacy in seronegative cases, are scarce, the main rationale of this study was to evaluate immunotherapy response in seronegative AE in comparison to seropositive cases.

Methods

An electronic database search retrospectively identified 150 AE patients, treated in our tertiary care university hospital between 2010 and 2020 with an AE. Therapy response was measured using both general impression and the modified Rankin Scale (mRS).

Results

Seventy-four AE patients (49.3%) were seronegative and 76 (50.7%) seropositive. These cases were followed up for a mean of 15.3 (standard deviation, SD, 24.9) and 24.3 months (SD 28.1), respectively. Both groups were largely similar on the basis of numerous clinical and paraclinical findings including cerebrospinal fluid, electroencephalography, magnetic resonance imaging, and 18-F-fluor-desoxy-glucose-positron-emmission-tomography pathologies. The majority of patients (80.4%) received at least one immunotherapy, which were glucocorticoids in most cases (76.4%). Therapy response on general impression was high with 49 (92.5%) of treated seronegative, and 57 (86.4%) of treated seropositive AE cases showing improvement following immunotherapies and not significantly different between both groups. Notably, the proportion of patients with a favorable neurological deficit (mRS 0-2) was twice as high during long-term follow-up as compared to baseline in both groups.

Conclusion

Since both, patients with seronegative and seropositive AE, substantially benefitted from immunotherapies, these should be considered in AE patients irrespective of their antibody results.

Spatial and Ecological Factors Modulate the Incidence of Anti-NMDAR Encephalitis-A Systematic Review

Anti-NMDAR encephalitis has been associated with multiple antigenic triggers (i.e., ovarian teratomas, prodromal viral infections) but whether geographic, climatic, and environmental factors might influence disease risk has not been explored yet. We performed a systematic review and a meta-analysis of all published papers reporting the incidence of anti-NMDAR encephalitis in a definite country or region. We performed several multivariate spatial autocorrelation analyses to analyze the spatial variations in the incidence of anti-NMDA encephalitis depending on its geographical localization and temperature. Finally, we performed seasonal analyses in two original datasets from France and Greece and assessed the impact of temperature using an exposure-lag-response model in the French dataset. The reported incidence of anti-NMDAR encephalitis varied considerably among studies and countries, being higher in Oceania and South America (0.2 and 0.16 per 100,000 persons-year, respectively) compared to Europe and North America (0.06 per 100,000 persons-year) (p < 0.01). Different regression models confirmed a strong negative correlation with latitude (Pearson's R = -0.88, p < 0.00001), with higher incidence in southern hemisphere countries far from the equator. Seasonal analyses showed a peak of cases during warm months. Exposure-lag-response models confirmed a positive correlation between extreme hot temperatures and the incidence of anti-NMDAR encephalitis in France (p = 0.03). Temperature analyses showed a significant association with higher mean temperatures and positive correlation with higher ultraviolet exposure worldwide. This study provides the first evidence that geographic and climatic factors including latitude, mean annual temperature, and ultraviolet exposure, might modify disease risk.

Paraneoplastic neurological syndromes of the central nervous system: a single institution 7-year case series

BACKGROUND

Paraneoplastic neurological syndromes (PNSs) are nonmetastatic complications of malignancy, defined by the presence of onconeural antibodies (ONAs). ONAs may be found in 60% of patients with central nervous system (CNS) involvement, and they are directed against intraneuronal antigens or channels, receptors or associated proteins located at the synaptic or extra-synaptic neuronal cell membrane. Given its rare incidence, there are few epidemiological case series on CNS-PNS. We aim to discuss the variability of CNS-PNSs etiology, clinical features, management and outcome, highlighting the importance of early recognition and appropriate treatment, leading to significant reduction of mortality and morbidity.

METHODS

We retrospectively reviewed our 7-years single-center experience, and specifically discussed the underlying etiology, parenchymal CNS involvement, and the acute treatment response. Only cases fulfilling PNS Euronetwork criteria for definitive PNS were included.

RESULTS

A total of 26 probable PNSs cases involving CNS were identified. We reported medical records of eleven (42.3%) illustrative cases, meeting the criteria of definite PNS and presenting variable clinical spectrum and different radiological appearances. Our series has a relative paucity of the most common syndromes and larger portion of clinical diagnosis with ONAs. Well-characterized ONAs had been detected in CSF of six patients.

CONCLUSIONS

Our case series supports the utmost importance of early recognition of CNS-PNSs. Screening for occult malignancies should not be limited to patients with classical CNS syndrome. Empiric immunomodulatory therapy may be considered before the diagnostic evaluation is completed, in order to prevent unfavorable outcome. Late presentations should not discourage initiation of treatment.

mNGS facilitates the accurate diagnosis and antibiotic treatment of suspicious critical CNS infection in real practice: A retrospective study

Whether metagenomic next-generation sequencing (mNGS) could benefit patients with suspected severe central nervous system (CNS) infection in terms of diagnosis and antibiotic treatment remains unknown. We retrospectively analyzed 79 patients with suspected CNS infection and undertook mNGS. The value of mNGS was investigated in terms of identification of pathogen and guidance for the adjustment of antibiotic treatment. The relationship between the time of initiating mNGS since onset and the Glasgow Outcome Scale (GOS) score after 90-day follow-up were analyzed. Fifty out of 79 cases with suspicious severe CNS infection were finally diagnosed. Despite previous routine laboratory tests, mNGS further promoted the accurate identification of pathogens in 23 cases (47.9%). The sensitivity, specificity, and accuracy of mNGS test in this study were 84.0, 79.3, and 82.3%, respectively. Furthermore, mNGS facilitated the adjustment of empirical antibiotic treatments in 38 cases (48.1%). The time of taking mNGS since onset had an insignificant weak positive correlation with GOS after 90-day follow-up (r = -0.73, P = 0.08). mNGS facilitated the accurate identification of pathogens in suspicious severe CNS infections and promoted the accurate antibiotic therapy even empirical antibiotics were administrated. It should be taken as early as possible to improve the clinical outcome of patients with suspicious severe CNS infection.

The study of neural antibodies in neurology: A practical summary

The field of Autoimmune Neurology is expanding rapidly, with new neural antibodies being identified each year. However, these disorders remain rare. Deciding when to test for these antibodies, when and what samples are to be obtained, how to handle and study them correctly, and how to interpret test results, is complex. In this article we review current diagnostic techniques and provide a comprehensive explanation on the study of these patients, in an effort to help with correct diagnosis minimizing false positive and false negative results. We also propose routine storage of samples and referral of certain cases to specialized research laboratories.

Second-line immunotherapy and functional outcomes in autoimmune encephalitis: A systematic review and individual patient data meta-analysis

Autoimmune encephalitis (AE) is a neurological disorder caused by autoimmune attack on cerebral proteins. Experts currently recommend staged immunotherapeutic management, with first-line immunotherapy followed by second-line immunotherapy if response to first-line therapy is inadequate. Meta-analysis of the evidence base may provide higher quality evidence to support this recommendation. We undertook a systematic review of observational cohort studies reporting AE patients treated with either second-line immunotherapy or first-line immunotherapy alone, and outcomes reported using the modified Rankin Scale (mRS; search date: April 22, 2020). We performed several one-stage multilevel individual patient data (IPD) meta-analyses to examine the association between second-line immunotherapy and final mRS scores (PROSPERO ID CRD42020181805). IPD were obtained for 356 patients from 25 studies. Most studies were rated as moderate to high risk of bias. Seventy-one patients (71/356, 19%) were treated with second-line immunotherapy. We did not find a statistically significant association between treatment with second-line immunotherapy and final mRS score for the cohort overall (odds ratio [OR] = 1.74, 95% confidence interval [CI] = .98-3.08, p = .057), or subgroups with anti-N-methyl-D-aspartate receptor encephalitis (OR = 1.03, 95% CI = .45-2.38, p = .944) or severe AE (maximum mRS score > 2; OR = 1.673, 95% CI = .93-3.00, p = .085). Treatment with second-line immunotherapy was associated with higher final mRS scores in subgroups with anti-leucine-rich glioma-inactivated 1 AE (OR = 6.70, 95% CI = 1.28-35.1, p = .024) and long-term (at least 12 months) follow-up (OR = 3.94, 95% CI = 1.67-9.27, p = .002). We did not observe an association between treatment with second-line immunotherapy and lower final mRS scores in patients with AE. This result should be interpreted with caution, given the risk of bias, limited adjustment for disease severity, and insensitivity of the mRS in estimating psychiatric and cognitive disability.

Clinical Characteristics and Prognosis of Antibody-Negative Autoimmune Encephalitis in Children: A Single-Center Retrospective Study

BACKGROUND

Autoimmune encephalitis (AE) is a group of immune-mediated brain diseases. However, new diagnostic criteria for AE in children indicate that partial pediatric patients with AE may be diagnosed without evidence of positive autoantibodies. Therefore, the clinical characteristics and prognosis of children with antibody-negative but probable AE require further investigation.

METHODS

Forty-one children with AE admitted to our hospital from April 2014 to January 2021 were retrospectively enrolled in this study. Children were divided into two groups according to positive or negative antibody tests. Clinical characteristics, cerebrospinal fluid, video electroencephalography, brain magnetic resonance imaging, and prognosis were analyzed, and the correlation between modified Rankin scale (mRS) and neutrophil-to-lymphocyte ratio (NLR) was examined.

RESULTS

Of 41 children, 16 cases tested positive for autoantibodies. The main features were psychiatric symptoms, cognitive disturbances, speech disturbances, movement disorders, and seizures. All the children were given a combination of intravenous methylprednisolone pulses with intravenous immunoglobulin therapy; 26 cases (63%) had a good outcome, and 15 cases (37%) had a poor outcome. Antibody-positive and antibody-negative but probable AE were analyzed by univariate analysis and showed lower lymphocyte counts and higher NLR and mRS scores in the antibody-negative group (P < 0.05). The Spearman rank correlation analysis showed a positive correlation between NLR level and mRS scores (P < 0.05).

CONCLUSIONS

Antibody-negative but possible AE is frequent in children who may have a more severe neurological impairment and higher NLR than antibody-positive AE. Aggressive immunotherapy in antibody-negative AE is essential to achieve a good prognosis.

Seronegative autoimmune diseases: A challenging diagnosis

Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.

Paraneoplastic Neurological Syndromes: Transitioning Between the Old and the New

PURPOSE OF REVIEW

Paraneoplastic neurological syndromes (PNS) are caused by nervous system-targeting aberrant anti-tumoral immune responses. We review the updated criteria for PNS diagnosis, incorporating novel information on clinical phenotypes, neuronal autoantibodies (Nabs), and tumors. The impact of the oncologic use of immune checkpoint inhibitors (ICI) on PNS occurrence is also addressed.

RECENT FINDINGS

Clinical phenotypes and Nabs are redefined as "high/intermediate/low" risk, following the frequency of cancer association. Nabs, the diagnostic hallmark of PNS, can target intracellular or surface neuronal proteins, with important prognostic and pathogenic implications. Many novel assays have been incorporated into laboratory diagnostics, that is becoming increasingly complex. ICI fight tumors, but favor autoimmunity, thus increasing the incidence of PNS-like disorders. Overcoming the old PNS criteria, the new ones are centered around the presence of tumor. Clinical presentation, Nabs, and tumor findings are translated in diagnostic scores, providing a useful tool for PNS diagnosis and management.

Diagnosis and Management of Suspected Pediatric Autoimmune Encephalitis: A Comprehensive, Multidisciplinary Approach and Review of Literature

Autoimmune encephalitis is an increasingly recognized entity in children. When treated promptly, favorable outcomes are seen in a majority of pediatric patients. However, recognition of autoimmune encephalitis in young patients is challenging. Once autoimmune encephalitis is suspected, additional difficulties exist regarding timing of treatment initiation and duration of treatment, as evidence to guide management of these patients is emerging. Here, we review available literature regarding pediatric autoimmune encephalitis and present our institution's comprehensive approach to the evaluation and management of the disease. These guidelines were developed through an iterative process involving both pediatric neurologists and rheumatologists.

Psychiatric symptoms as initial manifestation in neuromyelitis optica spectrum disorder without cortical lesions: A report of two cases

Diagnosing neuromyelitis optica spectrum disorder (NMOSD) remains a challenge, especially in patients with atypical presentations. Here, we describe two NMOSD patients who initially presented psychiatric symptoms without cortical lesions. This report expands our understanding of the possible presentations of NMOSD. Knowledge of rare initial symptoms may allow timely diagnosis and early therapeutic intervention, preventing more severe attacks affecting the spinal cord or eyes.

Diagnostic utility of cerebrospinal fluid (CSF) findings in seizures and epilepsy with and without autoimmune-associated disease

Patients with seizures and epilepsy routinely undergo multiple diagnostic tests, which may include cerebrospinal fluid (CSF) analysis. This review aims to outline different CSF parameters and their alterations in seizures or epilepsy. We then discuss the utility of CSF analysis in seizure patients in different clinical settings in depth. Some routine CSF parameters are frequently altered after seizures, but are not specific such as CSF protein and lactate. Pleocytosis and CSF specific oligoclonal bands are rare and should be considered as signs of infectious or immune mediated seizures and epilepsy. Markers of neuronal damage show conflicting results, and are as yet not established in clinical practice. Parameters of neuronal degeneration and more specific immune parameters are less well studied, and are areas of further research. CSF analysis in new-onset seizures or status epilepticus serves well in the differential diagnosis of seizure etiology. Here, considerations should include autoimmune-associated seizures. CSF findings in these disorders are a special focus of this review and are summarized in a comprehensive overview. Until now, CSF analysis has not yielded clinically helpful biomarkers for refractory epilepsy or for assessment of neuronal damage which is a subject of further studies.

Clinical Features and Treatment Outcomes of Seronegative Pediatric Autoimmune Encephalitis

Background and Purpose

New diagnostic criteria for pediatric autoimmune encephalitis (AIE) have been introduced recently. A substantial proportion of cases of pediatric AIE are diagnosed as seronegative based on these criteria, and so the clinical characteristics of this group remain to be investigated.

Methods

This study included 46 pediatric patients younger than 18 years with suspected AIE. Clinical features, laboratory or radiological findings, and treatment outcomes were compared between seronegative and seropositive patients.

Results

Nine (19.6%) of the 46 patients were diagnosed as seropositive AIE. All of the patients with seropositive AIE had anti-N-methyl-D-aspartate receptor antibodies. Commonly identified neuropsychiatric symptoms were altered mental status, cognitive dysfunction, seizure, speech dysfunction, and psychotic disorder in both the seronegative and seropositive groups. Immunotherapy produced favorable treatment outcomes in both the seropositive (n=7, 77.8%) and seronegative (n=35, 94.6%) AIE patients. Treatment outcomes for first-line immunotherapy were better in seronegative AIE than seropositive AIE patients (p=0.003), and hence a smaller proportion of seronegative patients required second-line treatment (p=0.015).

Conclusions

Pediatric seronegative AIE patients showed clinical presentations similar to those of seropositive AIE patients, with favorable treatment outcomes after immunotherapy.

Diagnosis of pediatric anti-NMDAR encephalitis at the onset: A clinical challenge

BACKGROUNDS

To investigate the clinical and instrumental features at the onset addressing to the diagnosis of anti-NMDAR encephalitis.

METHODS

Twenty children (age: 15 months-17 years; 7 males, 13 females) with initial suspected diagnosis of autoimmune encephalitis, observed between January 2008 and March 2018, were included. The final diagnosis was anti-NMDAR encephalitis in 7 children, other/probable autoimmune encephalitis in 7 children, and primary psychosis in the remaining 6 children.

RESULTS

At the clinical onset, anxiety disorder was the main symptom that helped in distinguishing the group of psychotic children from children with non-infectious encephalitis (P = 0.05 OR = 0.001), while epileptic seizures strongly predicted anti-NMDAR encephalitis (P = 0.04 OR = 28.6). At the onset, anti-NMDAR encephalitis could be distinguished from other/probable autoimmune encephalitis for the presence of sleep/wake rhythm alteration (P = 0.05 OR = 15). Among the symptoms occurring during the hospitalization, movement disorders (P = 0.031 OR = 12) were predictive of non-infectious encephalitis rather than primary psychosis. More specifically, the occurrence of language impairment (P = 0.03 OR = 33), epileptic seizures (P = 0.04 OR = 28.6) and catatonia (P = 0.03, OR = 33), were predictive of anti-NMDAR encephalitis. Also at this stage, anxiety disorder (P = 0.03 OR = 0.033) was predictive of primary psychosis.

CONCLUSION

Our findings suggest that at the clinical onset epileptic seizures and sleep/wake rhythm alteration represent the main features addressing to the diagnosis of anti-NMDAR encephalitis rather than primary psychosis and other/probable autoimmune encephalitis, while anxiety disorder could be a solid predictor of primary psychosis.

Antibody-negative autoimmune encephalitis as a complication of long-term immune-suppression for liver transplantation

Autoimmune encephalitis is a rare spectrum of disease that can be a complication of chronic immunosuppression. Diagnosis often requires the presence of antineuronal antibodies, but many causative antibodies have not yet been identified. Antibody-negative autoimmune encephalitis (AbNAE) is especially difficult to diagnose and must rely largely on exclusion of other causes. In chronically immune-suppressed transplant recipients, the differential is broad, likely resulting in underdiagnosis and worse outcomes. Here, we present a 58-year-old liver transplant recipient taking tacrolimus for prevention of chronic rejection who presented with 5 days of confusion, lethargy and lightheadedness. He was diagnosed with AbNAE after an extensive workup and recovered fully after high-dose corticosteroids. Our case highlights the importance of recognising the association between chronic immunosuppression and autoimmune encephalitis. Autoimmune encephalitis, even in the absence of characterised antibodies, should be considered when transplant recipients present with central neurologic symptoms.

Anti-N-methyl-D-aspartate-receptor antibody encephalitis combined with syphilis: A case report

BACKGROUND

Anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis is a common type of autoimmune encephalitis characterized by complex clinical signs and variable imaging manifestations. The pathogenesis of the disease is unclear. Syphilis is an infectious disease caused by Treponema pallidum that can invade the nervous and immune systems and cause systemic symptoms. There are few reports of anti-NMDAR encephalitis with syphilis, and the association between them is unknown; both diseases are related to immune system damage. We report a case of anti-NMDAR encephalitis with syphilis.

CASE SUMMARY

A 32-year-old man was admitted to our hospital with complaints of cognitive decline, diplopia, and walking instability during the previous 6 mo. He developed dysarthria, difficulty swallowing, and involuntary shaking of his head, neck, and limbs during the month prior to presentation. Cranial magnetic resonance imaging showed symmetrical abnormal signals in the pons, midbrain, and bilateral basal ganglia, and inflammatory demyelination was considered. The diagnosis of syphilis was confirmed based on the syphilis diagnosis test and the syphilis rapid test. He was given anti-syphilis treatment, but the above symptoms gradually worsened. Anti-NMDAR antibody was positive in cerebrospinal fluid but was negative in serum. Due to the cerebrospinal fluid findings, anti-NMDAR encephalitis was a consideration. According to the patient’s weight, he was treated with intravenous methylprednisolone 1 g QD for 5 d, with the dose gradually decreased for 6 mo, and immunoglobulin 25 g QD for 5 d; his symptoms improved after treatment.

CONCLUSION

This case shows that anti-NMDAR encephalitis may be combined with syphilis, which should be recognized to avoid misdiagnosis and treatment delay.