Autoimmune encephalitis update

Antibody-secreting cells as a source of NR1-IgGs in N-methyl-D-aspartate receptor-antibody encephalitis

BACKGROUND

The pathogenicity of NR1-IgGs in N-methyl-D-aspartate receptor (NMDAR)-antibody encephalitis is known, but the immunobiological mechanisms underlying their production remain unclear.

METHODS

For the first time, we explore the origin of NR1-IgGs and evaluate the contribution of B-cells to serum NR1-IgGs levels. Peripheral blood mononuclear cells (PBMCs) were obtained from patients and healthy controls (HCs). Naïve, unswitched memory (USM), switched memory B cells (SM), antibody-secreting cells (ASCs), and PBMC depleted of ASCs were obtained by fluorescence-activated cell sorting and cultured in vitro.

RESULTS

For some patients, PBMCs spontaneously produced NR1-IgGs. Compared to the patients in PBMC negative group, the positive group had higher NR1-IgG titers in cerebrospinal fluid and Modified Rankin scale scores. The proportions of NR1-IgG positive wells in PBMCs cultures were correlated with NR1-IgGs titers in serum and CSF. The purified ASCs, SM, USM B cells produced NR1-IgGs in vitro. Compared to the patients in ASCs negative group, the positive group exhibited a worse response to second-line IT at 3-month follow-up. Naïve B cells also produce NR1-IgGs, implicating that NR1-IgGs originate from naïve B cells and a pre-germinal centres defect in B cell tolerance checkpoint in some patients. For HCs, no NR1-IgG from cultures was observed. PBMC depleted of ASCs almost eliminated the production of NR1-IgGs.

CONCLUSIONS

These collective findings suggested that ASCs might mainly contribute to the production of peripheral NR1-IgG in patients with NMDAR-antibody encephalitis in the acute phase. Our study reveals the pathogenesis and helps develop tailored treatments (eg, anti-CD38) for NMDAR-antibody encephalitis.

Prediction of Seropositivity in Suspected Autoimmune Encephalitis by Use of Radiomics: A Radiological Proof-of-Concept Study

In this study, we sought to evaluate the capabilities of radiomics and machine learning in predicting seropositivity in patients with suspected autoimmune encephalitis (AE) from MR images obtained at symptom onset. In 83 patients diagnosed with AE between 2011 and 2022, manual bilateral segmentation of the amygdala was performed on pre-contrast T2 images using 3D Slicer open-source software. Our sample of 83 patients contained 43 seropositive and 40 seronegative AE cases. Images were obtained at our tertiary care center and at various secondary care centers in North Rhine-Westphalia, Germany. The sample was randomly split into training data and independent test data. A total of 107 radiomic features were extracted from bilateral regions of interest (ROIs). Automated machine learning (AutoML) was used to identify the most promising machine learning algorithms. Feature selection was performed using recursive feature elimination (RFE) and based on the determination of the most important features. Selected features were used to train various machine learning algorithms on 100 different data partitions. Performance was subsequently evaluated on independent test data. Our radiomics approach was able to predict the presence of autoantibodies in the independent test samples with a mean AUC of 0.90, a mean accuracy of 0.83, a mean sensitivity of 0.84 and a mean specificity of 0.82, with Lasso regression models yielding the most promising results. These results indicate that radiomics-based machine learning could be a promising tool in predicting the presence of autoantibodies in suspected AE patients. Given the implications of seropositivity for definitive diagnosis of suspected AE cases, this may expedite diagnostic workup even before results from specialized laboratory testing can be obtained. Furthermore, in conjunction with recent publications, our results indicate that characterization of AE subtypes by use of radiomics may become possible in the future, potentially allowing physicians to tailor treatment in the spirit of personalized medicine even before laboratory workup is completed.

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.

Differential effects of bilateral hippocampal CA3 damage on the implicit learning and recognition of complex event sequences

Learning regularities in the environment is a fundament of human cognition, which is supported by a network of brain regions that include the hippocampus. In two experiments, we assessed the effects of selective bilateral damage to human hippocampal subregion CA3, which was associated with autobiographical episodic amnesia extending ~50 years prior to the damage, on the ability to recognize complex, deterministic event sequences presented either in a spatial or a non-spatial configuration. In contrast to findings from related paradigms, modalities, and homologue species, hippocampal damage did not preclude recognition memory for an event sequence studied and tested at four spatial locations, whereas recognition memory for an event sequence presented at a single location was at chance. In two additional experiments, recognition memory for novel single-items was intact, whereas the ability to recognize novel single-items in a different location from that presented at study was at chance. The results are at variance with a general role of the hippocampus in the learning and recognition of complex event sequences based on non-adjacent spatial and temporal dependencies. We discuss the impact of the results on established theoretical accounts of the hippocampal contributions to implicit sequence learning and episodic memory.

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.

Controversies in immunotherapy for anti-NMDA receptor encephalitis: a scoping review with a proposal of operational definitions

Anti-NMDA receptor encephalitis (NMDARE), an autoimmune encephalitis associated with autoantibodies against the N-methyl-D-aspartate (NMDA) receptor, affects predominantly young women and is associated with psychiatric symptoms, seizures, movement disorders, and autonomic instability. Traditional treatments of anti-NMDA receptor encephalitis involve corticosteroids, intravenous immunoglobulin, plasmapheresis, cyclophosphamide, and rituximab. However, many controversies remain in the treatment for NMDA receptor encephalitis, such as optimal timing and combination of different immunotherapies, the role of newer strategies (e.g., bortezomib or tocilizumab) for severe and refractory patients, and the need or not for long-term immunosuppression. Our goal was to perform a scoping review to discuss the controversial topics of immunotherapy for NMDA receptor encephalitis and propose operational definitions to guide clinical practice and future research in the field.

Autoimmune encephalitis during pregnancy: A diagnostic and therapeutic challenge-A systematic review with individual patients' analysis and clinical recommendations

Several reports have described the autoimmune encephalitis' (AE) possible onset during pregnancy. In this systematic review, we summarize the available data on the diagnostic and therapeutic approach to AE during pregnancy, highlighting the associated maternal and fetal clinical outcomes. A systematic search of the literature was performed. The following databases were used: PubMed, Google Scholar, EMBASE, and CrossRef. The revision was registered on the PROSPERO platform (CRD42022336357). Forty-nine patients were included. AE onset was mainly observed during the first and the second trimester of pregnancy with psychiatric manifestations and seizures as main onset symptoms. CSF analysis showed AE-specific autoantibody positivity in 33 patients (anti-NMDA receptor as the most frequent). EEG generally showed normal findings. MRI revealed pathological findings in less than half of patients. Tumor screening was positive in 14 cases. First-line immunotherapy (single or combined) was generally employed while second line was administered in a minority of patients. Levetiracetam was the most used antiseizure medication. Cesarean section was performed in 18 women. Most of the women had an excellent early outcome after delivery but 22 showed persistent neurological deficits in long-term follow-up. Fetal outcome was positive in 33 cases, whereas 12 cases of fetal death were reported. A logistic regression showed that no variable significantly influenced the odds of good/bad maternal and fetal clinical outcome. Diagnosis and treatment of AE during pregnancy is challenging. The rate of miscarriage in women with AE seems to be higher than the general population. In addition, mothers may show long-term neurological deficits.

The Management and Diagnosis of Anti-NMDA Receptor Autoimmune Encephalitis in Pregnant Women: A Case Report and Literature Review

Rationale: Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a form of autoimmune synaptic encephalitis, often mediated by neuronal surface antibodies. Clinically, it manifests through a diverse range of neurological and psychiatric symptoms, primarily affecting young women with ovarian teratoma, which is rare in pregnant women. Patient concerns: We report a case of a 35-year-old multiparous pregnant patient at 38 weeks of gestation presented to the emergency room with seizure, psychiatric symptoms like delirious speech with mystical visual and auditory hallucinations, bradylalia, and retrograde amnesia. Diagnosis: The diagnosis of autoimmune encephalitis with anti-NMDA antibodies was concluded by considering the lumbar puncture results, brain imaging, and the patient's persistent symptoms. Outcomes: This case is noteworthy for its rarity and the symptoms' breadth. At 38 weeks of gestation, the patient underwent a cesarean section, resulting in excellent maternal recovery observed during the 6-month follow-up and good neonatal adaptation. Lessons: Our goals include raising awareness about this condition and emphasizing the significance of early diagnosis. This encephalitis is treatable and potentially reversible, underscoring the importance of prompt identification.

Cerebrospinal fluid uric acid levels associated with disease severity in patients with anti-N-methyl-d-aspartate receptor encephalitis

INTRODUCTION

Uric acid (UA) is an important natural antioxidant and strong peroxynitrite scavenger, but little is known about central nervous system (CNS) levels of UA in patients with anti-N-methyl-d-aspartate receptor encephalitis (NMDARE).

METHODS

Cerebrospinal fluid (CSF) and serum levels of UA were determined in 72 patients with anti-NMDARE and 111 controls with non-inflammatory neurological diseases (NINDs). Serum UA levels were also evaluated in 132 healthy controls (HCs). CSF neuron-specific enolase (NSE) and blood-brain barrier (BBB) index were evaluated in patients with anti-NMDARE. The association of CSF UA levels with anti-NMDARE and its clinical parameters were evaluated in the patients.

RESULTS

CSF UA levels were lower in patients with anti-NMDARE than in patients with NINDs, especially in patients with severe impairments (modified Rankin Scale [mRS] scores >3 vs. ≤ 3, p = 0.006). Furthermore, serum UA levels in patients with anti-NMDARE were significantly lower than in patients with NINDs and HCs. CSF UA levels were significantly associated with mRS scores, and serum UA levels in patients with anti-NMDARE. Furthermore, CSF/serum UA ratio was significantly associated with BBB index.

CONCLUSIONS

CSF UA levels associated with disease severity and serum UA levels in patients with anti-NMDARE. And CSF/serum UA ratio correlated with BBB index, indicating that CSF and serum UA levels change similarly with BBB permeability in anti-NMDARE patients.

Clinical study of autonomic dysfunction in patients with autoimmune encephalitis

BACKGROUND

Autoimmune encephalitis (AE) is a collective name, covering an emerging spectrum of autoimmune-mediated neurological diseases related to antibodies and synaptic or intracellular proteins. Anti-NMDAR, anti-LGI1, and anti-GABABR are three types of neuronal cell surface antibodies. Autonomic dysfunction represents a frequently occurring clinical manifestation. This observational study purposes to investigate comparisons between two groups with or without autonomic dysfunction and detect the autonomic dysfunction and other indexes in anti-NMDAR, anti-LGI1, and anti-GABABR cohorts.

METHODS

Patients with anti-NMDAR, anti-LGI1 and anti-GABABR encephalitis were recruited from the May 2017 to the April 2022. The following information was recorded: age, age at onset, tumor presence, gender, prodromal symptoms, clinical manifestations, cranial magnetic resonance imaging, cerebrospinal fluid and blood examinations, and immunotherapy.

RESULTS

There were totally 161 patients enrolled in this study. Among these participants, 104 individuals (64.6%) presented autonomic dysfunction and the remaining 57 (35.4%) were free of autonomic dysfunction. Sinus tachycardia was the most common autonomic dysfunction, followed by pollakiuria/uroclepsia, feverscence, central hypoventilation, sinus bradycardia, constipation, uroschesis, hyperhidrosis, hypersalivation, hypotension, and early satiety/emesis. Compared to patients without autonomic dysfunction, those with autonomic dysfunction had a higher incidence of central hypoventilation and ICU admissions. Meanwhile, in both groups with or without autonomic dysfunction, meatal behavior disorder, cognitive impairment, and epileptic seizure were three most common clinical manifestations. There were no significant differences in cranial magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) examination, antibody titers and number of immunotherapy types. Further analysis of AE mediated by distinct neuronal surface antibodies demonstrated that there were 85 anti-NMDAR, 56 anti-LGI1, and 20 anti-GABABR encephalitis patients. The significant differences between these three cohorts appeared in age, tumor presence, fervescence presence and antibody titers.

CONCLUSION

This study demonstrated the comparisons between autonomic dysfunction group and autonomic dysfunction-free group and provided insights into better diagnosis and treatment.

Long-term efficacy and safety of different corticosteroid courses plus mycophenolate mofetil for autoimmune encephalitis with neuronal surface antibodies without tumor

Objective

To compare the efficacy and safety of different-course corticosteroids plus mycophenolate mofetil (MMF) as maintenance therapy in autoimmune encephalitis (AE) with neuronal surface antibodies (NSAbs) without tumor and explore the optimal course of corticosteroids.

Methods

Fifty-five patients with definite AE without tumor were enrolled consecutively between June 2015 and November 2020 and retrospectively divided three groups according to the course of treatment with corticosteroid, i.e., a group of patients with a course of 3-6 months (Group 3-6mo), 6-12 months (Group 6-12mo), and >12 months (Group >12mo). Demographic data, clinical manifestation and ancillary tests results were recorded. The dosage and courses of corticosteroid treatment, the recovery of neurological function, the occurrence of adverse effects, and relapses were followed up.

Results

A total of 55 patients were included in the final analysis. The numbers of patients in Group 3-6 mo, Group 6-12 mo, and Group >12 mo was 14, 17, and 24, respectively. A significantly higher proportion of patients in Group >12 mo showed a decreased level of consciousness at the onset (12, 50%) than in Group 3-6 mo and Group 6-12 mo (2,14.3%; 3, 17.6%) (p = 0.033). The incidence of MRI abnormalities was significantly higher in Group 6-12 mo and Group >12 mo (10, 58.8%; 16, 66.7%) than in Group 3-6 mo (3, 21.4%) (P=0.023). Ordinal regression analysis indicated that decreased level of consciousness was associated with the course of corticosteroid (OR=3.838, 95% CI: 1.103-13.323, P=0.035). No significant difference was observed between the three groups regarding the cumulative dose of corticosteroids administered during the first three months of long-term treatment (P>0.05). Additionally, no significant difference in the cumulative dosage of corticosteroids was found between patients in Group 6-12 months and Group >12 months during the first 6 months after beginning long-term treatment. The mRS scores of the three groups were not statistically significant before and after first-line treatment or at the last follow-up. Bonferroni multiple comparison test indicated that the mRS scores of patients in Group 6-12 months and Group >12 months were not statistically significant at 3 months and 12 months after the start of long-term treatment. During the follow-up, 50 (90.9%) patients achieved satisfactory neurological function (mRS score ≤2). Five patients (9.1%) experienced a first relapse and 2 of them were overlapped with both anti-NMDA receptor and glial antibodies. The incidence of adverse effects was significantly higher in Group >12 mo (17, 70.8%) than in Group 3-6 mo (3, 21.4%) and Group 6-12 mo (5, 29.4%) (P=0.003).

Conclusions

The beneficial effects of oral corticosteroid treatment may do not persist beyond 12 months and may even contribute to an increased incidence of adverse effects. In order to optimize the effectiveness and safety of treatment, we recommend a corticosteroid course of 3-12 months. Patients with reduced levels of consciousness may be more inclined to choose longer courses of corticosteroids for long-term treatment. Patients with an "overlapping syndrome" may require more intense immunotherapy to prevent relapse.

MR Imaging Findings in a Large Population of Autoimmune Encephalitis

BACKGROUND AND PURPOSE

Autoimmune encephalitis is a rare condition in which autoantibodies attack neuronal tissue, causing neuropsychiatric disturbances. This study sought to evaluate MR imaging findings associated with subtypes and categories of autoimmune encephalitis.

MATERIALS AND METHODS

Cases of autoimmune encephalitis with specific autoantibodies were identified from the medical record (2009-2019). Cases were excluded if no MR imaging of the brain was available, antibodies were associated with demyelinating disease, or >1 concurrent antibody was present. Demographics, CSF profile, antibody subtype and group (group 1 intracellular antigen or group 2 extracellular antigen), and MR imaging features at symptom onset were reviewed. Imaging and clinical features were compared across antibody groups using χ2 and Wilcoxon rank-sum tests.

RESULTS

Eighty-five cases of autoimmune encephalitis constituting 16 distinct antibodies were reviewed. The most common antibodies were anti-N-methyl-D-aspartate (n = 41), anti-glutamic acid decarboxylase (n = 7), and anti-voltage-gated potassium channel (n = 6). Eighteen of 85 (21%) were group 1; and 67/85 (79%) were group 2. The median time between MR imaging and antibody diagnosis was 14 days (interquartile range, 4-26 days). MR imaging had normal findings in 33/85 (39%), and 20/33 (61%) patients with normal MRIs had anti-N-methyl-D-aspartate receptor antibodies. Signal abnormality was most common in the limbic system (28/85, 33%); 1/68 (1.5%) had susceptibility artifacts. Brainstem and cerebellar involvement were more common in group 1, while leptomeningeal enhancement was more common in group 2.

CONCLUSIONS

Sixty-one percent of patients with autoimmune encephalitis had abnormal brain MR imaging findings at symptom onset, most commonly involving the limbic system. Susceptibility artifact is rare and makes autoimmune encephalitis less likely as a diagnosis. Brainstem and cerebellar involvement were more common in group 1, while leptomeningeal enhancement was more common in group 2.

Epidemic Japanese B encephalitis combined with contactin-associated protein-like 2 antibody-positive autoimmune encephalitis: A case report

BACKGROUND

It is not uncommon to develop viral encephalitis. Epidemic Japanese B encephalitis infection combined with contactin-associated protein-like 2 (CASPR-2) antibody-positive autoimmune encephalitis has not been reported at present. In clinical work, we need to consider more options.

CASE SUMMARY

A 32-year-old male worker presented with headache, fever and call-unresponsive presentation. Complete cranial magnetic resonance image showed symmetrical abnormal signals in bilateral medial temporal lobe, bilateral thalamus and basal ganglia. Improved lumbar puncture showed that cerebrospinal fluid protein and cell count increased significantly. Viral encephalitis was considered, and the patient's consciousness still increased rapidly after antiviral treatment. Further detection of Cerebrospinal fluid Japanese B encephalitis virus Polymerase Chain Reaction positive, serum autoimmune encephalitis antibody showed CASPR-2 antibody positive (1:320), the patient's condition gradually improved after plasma exchange treatment. 3 mo later, the serum CASPR-2 antibody was negative and the patient's condition was stable.

CONCLUSION

This article reports the world’s first case of Epidemic Japanese B encephalitis infection combined with CASPR-2 antibody-positive autoimmune encephalitis, with a view to raising awareness.

Immune Mechanisms in Epileptogenesis: Update on Diagnosis and Treatment of Autoimmune Epilepsy Syndromes

Seizures and epilepsy can result from various aetiologies, yet the underlying cause of several epileptic syndromes remains unclear. In that regard, autoimmune-mediated pathophysiological mechanisms have been gaining attention in the past years and were included as one of the six aetiologies of seizures in the most recent classification of the International League Against Epilepsy. The increasing number of anti-neuronal antibodies identified in patients with encephalitic disorders has contributed to the establishment of an immune-mediated pathophysiology in many cases of unclear aetiology of epileptic syndromes. Yet only a small number of patients with autoimmune encephalitis develop epilepsy in the proper sense where the brain transforms into a state where it will acquire the enduring propensity to produce seizures if it is not hindered by interventions. Hence, the term autoimmune epilepsy is often wrongfully used in the context of autoimmune encephalitis since most of the seizures are acute encephalitis-associated and will abate as soon as the encephalitis is in remission. Given the overlapping clinical presentation of immune-mediated seizures originating from different aetiologies, a clear distinction among the aetiological entities is crucial when it comes to discussing pathophysiological mechanisms, therapeutic options, and long-term prognosis of patients. Moreover, a rapid and accurate identification of patients with immune-mediated epilepsy syndromes is required to ensure an early targeted treatment and, thereby, improve clinical outcome. In this article, we review our current understanding of pathogenesis and critically discuss current and potential novel treatment options for seizures and epilepsy syndromes of underlying or suspected immune-mediated origin. We further outline the challenges in proper terminology.

Autoimmune-mediated encephalitis and mimics: A neuroimaging review

Autoimmune encephalitis is a category of autoantibody-mediated neurological disorders that often presents a diagnostic challenge due to its variable clinical and imaging findings. The purpose of this image-based review is to provide an overview of the major subtypes of autoimmune encephalitis and their associated autoantibodies, discuss their characteristic clinical and imaging features, and highlight several disease processes that may mimic imaging findings of autoimmune encephalitis. A literature search on autoimmune encephalitis was performed and publications from neuroradiology, neurology, and nuclear medicine literature were included. Cases from our institutional database that best exemplify major imaging features were presented.

Advances in the Pathogenesis of Auto-antibody-Induced Cerebellar Synaptopathies

The presence of auto-antibodies that target synaptic machinery proteins was documented recently in immune-mediated cerebellar ataxias. The autoantigens include glutamic acid decarboxylase 65 (GAD65), voltage-gated Ca²⁺ channel (VGCC), metabotropic glutamate receptor type 1 (mGluR1), and glutamate receptor delta (GluRdelta). GAD65 is involved in the synthesis, packaging, and release of GABA, whereas the other three play important roles in the induction of long-term depression (LTD). Thus, the auto-antibodies toward these synaptic molecules likely impair fundamental synaptic machineries involved in unique functions of the cerebellum, potentially leading to the development of cerebellar ataxias (CAs). This concept has been substantiated recently by a series of physiological studies. Anti-GAD65 antibody (Ab) acts on the terminals of inhibitory neurons that suppress GABA release, whereas anti-VGCC, anti-mGluR1, and anti-GluR Abs impair LTD induction. Notably, the mechanisms that link synaptic dysfunction with the manifestations of CAs can be explained by disruption of the "internal models." The latter can be divided into three levels. First, since chained inhibitory neurons shape the output signals through the mechanism of disinhibition/inhibition, impairments of GABA release and LTD distort the conversion process from the "internal model" to the output signals. Second, these antibodies impair the induction of synaptic plasticity, rebound potentiation, and LTD, on Purkinje cells, resulting in loss of restoration and compensation of the distorted "internal models." Finally, the cross-talk between glutamate and microglia/astrocytes could involve a positive feedback loop that accelerates excitotoxicity. This mini-review summarizes the pathophysiological mechanisms and aims to establish the basis of "auto-antibody-induced cerebellar synaptopathies."

Neurosyphilis: The Great Imitator

Syphilis is a sexually transmitted disease caused by spirochete Treponema pallidum, with a growing incidence documented in recent years. Its clinical course is divided into three phases - primary, secondary, and tertiary syphilis - and virtually any organ can be affected, resulting in diverse clinical manifestations, making the diagnosis challenging. Neurosyphilis is a progressive, destructive disease of the central nervous system (CNS) that can develop at any stage of the infection, leading to meningeal involvement, meningovascular disease, or parenchymal syphilis (including tabes dorsalis and general paresis). Its clinical manifestations are heterogeneous and vary from focal neurologic signs to neuropsychiatric manifestations. The diagnosis is based mainly on the clinical picture and study of cerebrospinal fluid. Neuroimaging is helpful and sometimes essential, with magnetic resonance imaging being the most sensitive radiologic method, although there are no pathognomonic radiologic signs. Treatment of all forms of neurosyphilis is based on parenteral penicillin. We present a case of neurosyphilis in a patient presenting with a subacute confusional state and initial imaging findings suggestive of metastatic CNS lesions.

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.

Rare Etiologies in Immune-Mediated Cerebellar Ataxias: Diagnostic Challenges

The cerebellum is particularly enriched in antigens and represents a vulnerable target to immune attacks. Immune-mediated cerebellar ataxias (IMCAs) have diverse etiologies, such as gluten ataxia (GA), post-infectious cerebellitis (PIC), Miller Fisher syndrome (MFS), paraneoplastic cerebellar degeneration (PCD), opsoclonus myoclonus syndrome (OMS), and anti-GAD ataxia. Apart from these well-established entities, cerebellar ataxia (CA) occurs also in association with autoimmunity against ion channels and related proteins, synaptic adhesion/organizing proteins, transmitter receptors, glial cells, as well as the brainstem antigens. Most of these conditions manifest diverse neurological clinical features, with CAs being one of the main clinical phenotypes. The term primary autoimmune cerebellar ataxia (PACA) refers to ataxic conditions suspected to be autoimmune even in the absence of specific well-characterized pathogenic antibody markers. We review advances in the field of IMCAs and propose a clinical approach for the understanding and diagnosis of IMCAs, focusing on rare etiologies which are likely underdiagnosed. The frontiers of PACA are discussed. The identification of rare immune ataxias is of importance since they are potentially treatable and may lead to a severe clinical syndrome in absence of early therapy.

Pulmonary infection and baseline mRS scores predict poor prognosis in anti-GABABR encephalitis

Purpose

Anti-gamma-aminobutyric-acid type B receptor (anti-GABABR) encephalitis is a rare autoimmune condition caused by the presence of GABABR antibodies in the limbic system. However, its clinical features and prognostic factors are poorly understood. In this study, we aimed to explore factors that affect the response to first-line treatment in patients with anti-GABABR encephalitis.

Methods

Thirty-four patients with an initial diagnosis of anti-GABABR encephalitis were retrospectively enrolled from December 2015 to June 2021. Clinical features and experimental data recorded within 24 h of admission were extracted from the patients’ medical records. The modified Rankin Scale (mRS) was utilized to assess disease severity at admission and functional recovery after immunotherapy. Independent prognostic factors were determined by ordinal logistic regression analysis.

Results

Of the 34 anti-GABABR encephalitis patients, 12 (35%) presented with cancer; all of these patients had lung cancer. According to multivariate regression analysis, the cancer group exhibited a decrease in the peripheral blood absolute lymphocyte count (ALC) (odds ratio [OR]: 0.063, 95% confidence interval [CI]: 0.006-0.639, P=0.019) and hyponatremia (OR: 9.268, 95% CI: 1.054-81.502, 0.045). In addition, the neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR) and platelet/lymphocyte ratio (PLR) did not significantly differ according to mRS scores in patients receiving first-line treatment. No patients with mild or moderate mRS scores (0-2) at admission developed symptoms after treatment; in contrast, only 11 patients with a severe mRS scores (≥3, 11/18) experienced symptom alleviation. Ordinal regression analysis indicated that worse prognosis was associated with pulmonary infection (OR=9.885, 95% CI: 1.106-88.323, P=0.040) and baseline mRS scores (OR= 24.047, 95% CI: 3.294-175.739, P=0.002) in the adjusted model.

Conclusion

Our findings demonstrate that pulmonary infection and baseline mRS scores are independent risk factors for poor prognosis in patients with anti-GABABR encephalitis after first-line treatment. ALC and hyponatremia are potential biomarkers for anti-GABABR encephalitis cases accompanied by lung cancer.

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.

Advances in Potential Cerebrospinal Fluid Biomarkers for Autoimmune Encephalitis: A Review

Autoimmune encephalitis (AE) is a severe inflammatory disease of the brain. Patients with AE demonstrate amnesia, seizures, and psychosis. Recent studies have identified numerous associated autoantibodies (e.g., against NMDA receptors (NMDARs), LGI1, etc.) involved in the pathogenesis of AE, and the levels of diagnosis and treatment are thus improved dramatically. However, there are drawbacks of clinical diagnosis and treatment based solely on antibody levels, and thus the application of additional biomarkers is urgently needed. Considering the important role of immune mechanisms in AE development, we summarize the relevant research progress in identifying cerebrospinal fluid (CSF) biomarkers with a focus on cytokines/chemokines, demyelination, and nerve damage.

The Neutrophil-to-Lymphocyte and Monocyte-to-Lymphocyte Ratios Are Independently Associated With the Severity of Autoimmune Encephalitis

Background

The neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) are biomarkers that may reflect inflammatory status in some immune-related diseases. This study aims to investigate the association of NLR and MLR with the severity and prognosis of autoimmune encephalitis (AE).

Methods

A total of 199 patients diagnosed with AE in the First Affiliated Hospital of Zhengzhou University from October 2015 to October 2021 were retrospectively analyzed. The Clinical Assessment Scale for Autoimmune Encephalitis (CASE) and the modified Rankin Scale (mRS) were used to evaluate the severity of the patients at admission, and the patients were divided into mild group (CASE ≤ 4) and severe group (CASE ≥ 5) according to the CASE score. Poor prognosis was described as an mRS of 3 or more at 12 months. Binary logistic regression analysis was performed to assess risk factors for the severity and prognosis of AE.

Results

NLR and MLR of severe group were significantly higher than that of mild group. NLR and MLR were positively correlated with the CASE score (r = 0.659, P < 0.001; r = 0.533, P < 0.001) and the mRS score (r = 0.609, P < 0.001;r = 0.478, P < 0.001) in AE patients. Multivariate logistic analysis showed that NLR (OR = 1.475, 95%CI: 1.211-1.796, P < 0.001) and MLR (OR = 15.228, 95%CI: 1.654-140.232, P = 0.016) were independent risk factors for the severity of AE. In addition, the CASE score and the mRS score were positively correlated (r = 0.849, P < 0.001). Multivariate logistic analysis showed that the CASE at admission (OR = 1.133, 95%CI: 1.043-1.229, P = 0.003) and age (OR = 1.105, 95%CI: 1.062-1.150, P < 0.001) were independent risk factors for the poor prognosis of AE patients. The NLR and MLR at admission and whether they decreased after immunotherapy were not associated with the prognosis of AE patients (P > 0.05).

Conclusions

NLR and MLR, readily available and widespread inflammatory markers, were helpful for clinicians to monitor disease progression and identify potentially severe patients of AE early to optimize clinical treatment decisions.

Anti-dipeptidyl-peptidase-like protein 6 encephalitis with pure cerebellar ataxia: a case report

Background

Anti-dipeptidyl-peptidase-like protein 6 (DPPX) encephalitis is a rare autoimmune encephalitis. The clinical symptoms of anti-DPPX encephalitis are often severe, manifested as diarrhea/weight loss, central nervous system hyperexcitability and cognitive dysfunction.

Case presentation

An 18-year-old boy was admitted for 1-week-long cerebellar symptoms including dizziness, unsteady gait and frequent vomiting. Magnetic resonance imaging (MRI) displayed no abnormal findings. However, autoimmune encephalitis panel revealed anti-DPPX antibody was positive in the serum. This patient completely recovered after immunoglobulin and corticoids therapy. In addition, repeat serum antibody test for DPPX was negative within one month.

Conclusion

In addition to the classic triad, anti-DPPX encephalitis may manifest as mild and rare symptoms due to lower antibody titers. Fast identification of rare symptoms can help to quickly diagnosis and effective treatment.

Serum-Derived Exosomal miR-140-5p as a Promising Biomarker for Differential Diagnosis of Anti-NMDAR Encephalitis With Viral Encephalitis

Background

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is the most common type of autoimmune encephalitis. Early recognition and treatment, especially distinguishing from viral encephalitis (VE) in the early stages, are crucial for the outcomes of patients with anti-NMDAR encephalitis. Compared with plasma microRNAs (miRNAs), exosomal miRNAs are more abundant and not easy to degrade. Moreover, exosomes can pass through the blood–brain barrier. This study aimed to explore the clinical value of serum exosomal miRNAs in the differential diagnosis of anti-NMDAR encephalitis with VE.

Method

Serum samples from a total of 30 patients with anti-NMDAR encephalitis, 30 patients with VE, and 30 cases of control patients hospitalized in the same period were collected. Firstly, the serum exosomes were isolated and identified by transmission electron microscope (TEM), nanoparticle-tracking analyzer (NTA), and Western blot (WB). The expression levels of let-7b and miR-140-5p from serum exosomes were detected by real-time quantitative PCR (qPCR). At the same time, we also detected complement 3 (C3), complement 4 (C4), and high sensitivity CRP (hs-CRP) expression levels in three groups. Finally, we analyzed the difference and diagnostic value of the test results.

Results

Isolated particles showed identical characteristics to the exosomes through TEM, NTA, and WB analyses. Compared with the VE group and control group, the expression of miR-140-5p was significantly upregulated in serum exosomes of the NMDAR group. In contrast, the serum C3 in the NMDAR group was significantly lower than the other two groups. ROC curve analysis showed the area under the curve (AUC) of serum exosomal miR-140-5p and serum C3 was 0.748 (76.67% sensitivity and 73.33% specificity) and 0.724 (76.67% sensitivity and 60% specificity) to distinguish anti-NMDAR encephalitis from VE, respectively. The AUC of serum exosomal miR-140-5p combined with serum C3 was 0.811, the sensitivity was 70.00%, and the specificity was 86.67%.

Conclusion

Serum exosomal miR-140-5p combined with serum C3 would be a promising marker in the differential diagnosis of anti-NMDAR encephalitis with VE.

Imaging Aspects of the Hippocampus

The hippocampus is one of the most sophisticated structures in the brain, owing to its complex anatomy, intriguing functions, relationship with other structures, and relevant associated symptoms. Despite being a structure analyzed for centuries, its anatomy and physiology in the human body are still being extensively studied, as well as associated pathologic conditions and potential biomarkers. It can be affected by a broad group of diseases that can be classified as congenital, degenerative, infectious or inflammatory, neoplastic, vascular, or toxic-metabolic disease. The authors present the anatomy and close structures, function, and development of the hippocampus, as well as an original algorithm for imaging diagnosis. The algorithm includes pathologic conditions that typically affect the hippocampus and groups them into nodular (space occupying) and nonnodular pathologic conditions, serving as a guide to narrow the differential diagnosis. MRI is the imaging modality of choice for evaluation of the hippocampus, and CT and nuclear medicine also improve the analysis. The MRI differential diagnosis depends on anatomic recognition and careful characterization of associated imaging findings such as volumetric changes, diffusion restriction, cystic appearance, hyperintensity at T1-weighted imaging, enhancement, or calcification, which play a central role in diagnosis along with clinical findings. Some pathologic conditions arising from surrounding structures such as the amygdala are also important to recognize. Pathologic conditions of the hippocampus can be a challenge to diagnose because they usually manifest as similar clinical syndromes, so the imaging findings play a potential role in guiding the final diagnosis. Online supplemental material is available for this article. ^©RSNA, 2022.

Autoantibody-associated psychiatric syndromes: a systematic literature review resulting in 145 cases

BACKGROUND

Autoimmune encephalitis (AE) is an important consideration during the diagnostic work-up of secondary mental disorders. Indeed, isolated psychiatric syndromes have been described in case reports of patients with underlying AE. Therefore, the authors performed a systematic literature review of published cases with AE that have predominant psychiatric/neurocognitive manifestations. The aim of this paper is to present the clinical characteristics of these patients.

METHODS

The authors conducted a systematic Medline search via Ovid, looking for case reports/series of AEs with antineuronal autoantibodies (Abs) against cell surface/intracellular antigens combined with predominant psychiatric/neurocognitive syndromes. The same was done for patients with Hashimoto encephalopathy/SREAT. Only patients with signs of immunological brain involvement or tumors in their diagnostic investigations or improvement under immunomodulatory drugs were included.

RESULTS

We identified 145 patients with AE mimicking predominant psychiatric/neurocognitive syndromes. Of these cases, 64% were female, and the mean age among all patients was 43.9 (±22.1) years. Most of the patients had Abs against neuronal cell surface antigens (55%), most frequently against the NMDA-receptor (N = 46). Amnestic/dementia-like (39%) and schizophreniform (34%) syndromes were the most frequently reported. Cerebrospinal fluid changes were found in 78%, electroencephalography abnormalities in 61%, and magnetic resonance imaging pathologies in 51% of the patients. Immunomodulatory treatment was performed in 87% of the cases, and 94% of the patients responded to treatment.

CONCLUSIONS

Our findings indicate that AEs can mimic predominant psychiatric and neurocognitive disorders, such as schizophreniform psychoses or neurodegenerative dementia, and that affected patients can be treated successfully with immunomodulatory drugs.

Validation of the Clinical Assessment Scale in Autoimmune Encephalitis in Chinese Patients

Background and Objectives

The Clinical Assessment Scale in Autoimmune Encephalitis (CASE) is a scale for assessing severity in autoimmune encephalitis. We aimed to validate the CASE score in a Chinese population and evaluate its clinical significance.

Methods

Patients diagnosed with autoimmune encephalitis were recruited between June 2014 and May 2019 from two hospitals. CASE and modified Rankin Scale (mRS) scores were obtained. Data regarding clinical features, treatment, and available information were gathered from the hospital information system.

Results

Of the 176 patients with autoimmune encephalitis, 11 died and 14 had tumors. Ten patients received second-line treatment. The CASE scores of patients receiving second-line treatment were significantly higher (median CASE: 15) than in those receiving first-line treatment (median CASE: 8) (p<0.001). Twenty-two patients had poor functional status (mRS>2). Areas under the curve of CASE on whether functional status was poor at 1 year were 0.89 (p<0.001). Sixty patients were admitted to the intensive care unit (ICU), and the CASE scores were positively correlated with days in the ICU (r=0.58, p<0.001). There was no statistically significant association between the CASE scores and relapse (p=0.39>0.05). Additionally, the CASE scores were positively associated with the mRS scores (r=0.85 p<0.001).

Conclusions

The CASE score is suitable for the comprehensive assessment of Chinese patients with autoimmune encephalitis, which may help clinicians to select the appropriate intervention and estimate the disease severity and prognosis.

SCLC and anti‐GABABR encephalitis: A retrospective analysis of 60 cases in China

Background

Methods

Results

Conclusions

Efficacy and tolerability of intravenous immunoglobulin versus intravenous methylprednisolone treatment in anti- N-methyl-D-aspartate receptor encephalitis

OBJECTIVES

To compare the effectiveness and safety of intravenous immunoglobulin (IVIg) or intravenous methylprednisolone (IVMP) vs and IVIg plus IVMP (IPI) as initial therapy in anti- N-methyl-D-aspartate receptor (NMDAR) encephalitis.

METHODS

A multicenter study of prospectively identified NMDAR encephalitis individuals who presented from October, 2011, to August, 2020, to the study hospitals of western China, with a median follow-up of 3.9 years. Prespecified candidate variables were the prescriptions of IVIg, IVMP, or a combination of both. Propensity score matching was also performed to control potential confounders.

RESULTS

A total of 347 NMDAR encephalitis patients were finally analyzed in this study. After the TriMatch for NMDAR encephalitis, 37 triplets were generated. Compared to IVIg or IVMP, the administration of IPI exhibited a significant benefit of a higher response rate (86.5% vs. 55.6% vs. 68.7%, p^corr <0.01); improved mRS score at 3, 6, and 12 months (p^corr <0.05); and reduced further recurrence rate (10 of 37 [27.0%] vs 9 of 37 [24.3%] vs 2 of 37 [5.4%]; p log rank = 0.01). There was no association between treatment superiority and patient sex or the presence of tumors (p≥0.05). Patients treated with IVMP had a significantly higher number of adverse events, but 99% of adverse events were mild to moderate and did not lead to a change in treatment.

CONCLUSION

In patients with NMDAR encephalitis, adequate response, favorable outcome, and less recurrence were each more likely to occur in individuals treated with a combined immunotherapy than in monotherapy individuals.

More than just anti-NMDAR: the many facets of autoimmune encephalitis

This editorial expands on a Praxis article published by Beattie and colleagues in the trainees' section of this journal. The authors describe an interesting case of anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis, outline the clinical presentation and make suggestions on ways to approach this rare disorder. Here we provide an overview of autoimmune conditions that result in the production of autoantibodies targeting central nervous system proteins mediating autoimmune encephalitis and offer a perspective on approaches to diagnosis and treatment.

Systemic Inflammation Index Values Are Associated With Worsened Disease Severity and Poor Response to Autoimmune Encephalitis Treatment

Both specific and innate immune responses play important roles in autoimmune encephalitis (AE). We aimed to explore the predictive value of the systemic inflammation index (SII) at admission as a peripheral biomarker of treatment response of AE. A total of 146 patients diagnosed with AE in the First Affiliated Hospital of Zhengzhou University from January 1, 2018 to September 22, 2020 were retrospectively and consecutively analyzed as per the inclusion criteria and divided into two groups according to their response to immunotherapy after 30 days. The predictive value of the SII as a peripheral biomarker for AE treatment response was calculated using the receiver operating characteristic curve analysis, which showed that the best SII cut-off value for predicting poor response to AE treatment was 863.3; the area under the curve was 0.75, with 83.0% sensitivity and 72.0% specificity. The risk factors for poor response to AE treatment were analyzed; univariable analysis showed that the rate of decreased level of consciousness, rate of cognitive or mental behavior abnormality, cerebrospinal fluid pressure, blood neutrophils, platelets, time until treatment initiation, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio, and SII were significantly higher in patients with poor response to AE immunotherapy after 30 days than in patients with good response. Meanwhile, the blood lymphocyte counts and Glasgow Coma Scale (GCS) scores in patients with poor response were significantly lower than those in patients with good response (all p < 0.05), and multivariable binary logistic regression with backward stepwise method showed that decreased levels of consciousness, time until treatment initiation and SII were associated with poor response to immunotherapy. Moreover, the SII ≤ 863.3 group had lower rates of decreased consciousness levels, admission to the intensive care unit, and mechanical ventilation; lower cerebrospinal fluid pressure, blood neutrophil count, and platelet count; and higher blood lymphocyte count and GCS scores. The SII was associated with worsened disease severity and poor response to treatment after 30 days of the initially diagnosed AE, and patients with an SII > 863.3 were more likely to have poor response to immunotherapy.

Association of serum Gasdermin D with anti-N-methyl-D-aspartate receptor encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disease of the central nervous system. Gasdermin D (GSDMD) is associated with autoimmune disorders and neuroinflammatory disorders, but its role in anti-NMDAR encephalitis is unclear. In this study, we measured serum levels of GSDMD in 42 patients with anti-NMDAR encephalitis and 25 healthy controls. Of the 42 patients, 17 had follow-up evaluation of GSDMD levels and modified Rankin scale (mRS) scores at 3 months. Association of GSDMD with anti-NMDAR encephalitis and its clinical parameters were evaluated. Serum GSDMD levels were significantly higher in patients with anti-NMDAR encephalitis than in healthy controls (p = 0.002, p_adjusted  = 0.009), especially in males (p = 0.001, p_adjusted  = 0.022). This was also evident in patients with severe impairment (mRS >3 vs mRS ≤3; p < 0.001). Serum GSDMD was associated with mRS before and after adjustment for age and gender (r = 0.440 and 0.430, p = 0.004 and 0.006, respectively) as well as serum CH50 (r = -0.419 and -0.426, p = 0.011 and 0.012, respectively). Furthermore, 3-month follow-up evaluation revealed that after treatment, anti-NMDAR encephalitis patients had significantly decreased serum GSDMD levels (p = 0.007) and significantly decreased mRS scores (p = 0.002) compared with before treatment. Furthermore, the changes in mRS scores were negatively associated with changes in GSDMD levels, although the associations were not significant (r = -0.222, p = 0.393). Our findings show that serum GSDMD levels are elevated in anti-NMDAR encephalitis and are associated with disease prognosis.

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.

Clinical Course and Features of Seizures Associated With LGI1-Antibody Encephalitis

OBJECTIVE

To determine risk factors associated with clinical relapses and development of chronic epilepsy in patients with anti-leucine-rich glioma-inactivated 1 (LGI1) IgG encephalitis.

METHODS

Patients with seizures related to LGI1-antibody encephalitis with ≥ 24 months of follow-up from disease onset were identified in the Mayo Clinic electronic medical record and Neuroimmunology lab records. Charts were reviewed to determine clinical factors, seizure types, imaging, treatment, occurrence of relapse, and outcome. Binary logistic regression analysis was performed to identify predictors of the development of chronic epilepsy. Univariate Cox proportional hazards regression was used to examine the influence of baseline characteristics on relapse risk.

RESULTS

Forty-nine patients with LGI1-antibody encephalitis and acute symptomatic seizures were identified. Almost all patients (n=48, 98%) were treated with immunotherapy. Eight had definite, and two had possible chronic epilepsy at last follow-up (10/49, 20.4%). Female sex (P=0.048) and younger age at disease onset (P=0.02) were associated with development of chronic epilepsy. Relapses occurred in 20 (40.8%), with a median time to first relapse of 7.5 months (range 3-94 months). Initial treatment with chronic steroid sparing immunotherapy was associated with reduced risk of relapse (hazards ratio=0.28, 95% CI 0.11-0.73, P=0.009).

CONCLUSIONS

Chronic epilepsy occurred in 20.4% of our patients with LGI1-antibody encephalitis despite aggressive immunotherapy. Risk factors for chronic epilepsy were female sex and earlier age of onset. Relapses occurred in 40.8% of patients with prolonged follow-up, and chronic steroid sparing immunotherapy was associated with a lower relapse rate.

The Effectiveness of Electroconvulsive Therapy on Catatonia in a Case of Anti-N-Methyl-D-Aspartate (Anti-NMDA) Receptor Encephalitis

Catatonia is a symptom seen in a variety of neuropsychiatric conditions, including anti-N-Methyl D-aspartate receptor (NMDAR) encephalitis. When associated with anti-NMDAR encephalitis, catatonia is resistant to standard therapy. However, electroconvulsive therapy (ECT) has shown promising success in management. This case report presents a 25-year-old African American female who presented to the emergency room with nervousness, sweating, insomnia, and visual and auditory hallucinations. She was treated symptomatically for anxiety but returned to the hospital after she continued to experience worsening symptoms. Her anxiety worsened, and she became more agitated, warranting an extensive workup, including magnetic resonance imaging (MRI) and electroencephalogram (EEG), which showed normal findings. She also had an anti-NMDA receptor antibodies titer done, which showed a positive titer result. She was treated with intravenous steroids, intravenous immunoglobulin G (IgG), plasma exchange, and rituximab, which did not improve her symptoms, and she was discharged home after a prolonged hospital stay. On follow-up visits, she reported worsening confusion, aggression, and suicidal behaviors. The patient was readmitted, during which she experienced catatonia and psychiatric symptoms, and her anti-NMDAR titer had increased to 1:1280. Further treatments with intravenous steroids, intravenous IgG, plasma exchange, and rituximab, including haloperidol and clonazepam, failed to improve her condition. However, her condition improved remarkably following treatment with 12 rounds of ECT. No randomized control trial has been done to demonstrate the effectiveness of ECT in the treatment of anti-NMDAR encephalitis despite various reports of the effectiveness of this treatment modality. This case report adds to the growing clinical evidence in support of the use of ECT in anti-NMDAR encephalitis patients with catatonia. ECT can be incorporated as standard protocol in the treatment of catatonia and associated psychiatric symptoms when managing a patient with anti-NMDAR encephalitis associated with catatonic features.

Autoimmune encephalitis in a tertiary hospital in the Philippines

BACKGROUND

Autoimmune encephalitis (AE) is an emerging disorder in adults and children. Due to its potentially reversible nature, prompt recognition and intervention are of utmost importance.

OBJECTIVE

To describe the clinical and paraclinical features, as well as treatment outcomes of patients with AE admitted in a Philippine tertiary hospital.

METHODS

Retrospective case series of patients with definite AE.

RESULTS

Eighteen (18) patients were included (12 adults, 6 children), majority of whom had anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. The median age of onset was 32 (IQR: 10.8) years old and 13 (IQR: 4.8) years old in the adult and pediatric population, respectively. In both age groups, most presented with psychiatric symptoms and normal imaging findings. Cerebrospinal fluid (CSF) pleocytosis was detected in 8/12 (66.7%) adults and 2/6 (33.3%) children, while CSF protein elevation was only seen in 6/12 (50%) adults. Most patients presented with seizures, and the most frequent electroencephalography (EEG) abnormality detected was slow activity (70.5%). A high proportion of patients received high dose steroids, alone (35.3%) or in combination with intravenous immunoglobulin (IVIG, 52.9%). Overall, 66.7% had improved outcomes, mostly seen in the pediatric population.

CONCLUSION

This study highlighted the broad clinical phenotype, as well as the similarities and differences of AE manifestations in adults and children. It demonstrated the limited but supportive role of laboratory investigations in the diagnosis of AE. It also underscored the importance of early intervention in AE and highlighted factors influencing treatment practices and discharge outcomes in the local setting.

Autoimmune Encephalitis in Late-Onset Seizures: When to Suspect and How to Treat

Objective: This study was conducted to elucidate prevalence, clinical features, outcomes, and best treatment in patients with late-onset seizures due to autoimmune encephalitis (AE). Methods: This is a single-institution prospective cohort study (2012-2019) conducted at the Epilepsy Center at the University of Greifswald, Germany. A total of 225 patients aged ≥50 years with epileptic seizures were enrolled and underwent an MRI/CT scan, profiling of neural antibodies (AB) in serum and cerebrospinal fluid (CSF), and neuropsychological testing. On the basis of their work-up, patients were categorized into the following three cohorts: definite, suspected, or no AE. Patients with definite and suspected AE were subsequently treated with immunosuppressive therapy (IT) and/or anti-seizure drug (ASD) therapy and were followed up (FU) regarding clinical and seizure outcome. Results: Of the 225 patients, 17 (8%) fulfilled the criteria for definite or suspected AE according to their AB profile and MRI results. Compared with patients with no evidence of AE, those with AE were younger (p = 0.028), had mesial temporal neuropsychological deficits (p = 0.001), frequently had an active or known malignancy (p = 0.006) and/or a pleocytosis (p = 0.0002), and/or had oligoclonal bands in CSF (p = 0.001). All patients with follow-up became seizure-free with at least one ASD. The Modified Rankin scale (mRS) at hospital admission was low for patients with AE (71% with mRS ≤2) and further decreased to 60% with mRS ≤2 at last FU. Significance: AE is an important etiology in late-onset seizures, and seizures may be the first symptom of AE. Outcome in non-paraneoplastic AE was favorable with ASD and IT. AB testing in CSF and sera, cerebral MRI, CSF analysis, and neuropsychological testing for mesial temporal deficits should be part of the diagnostic protocol for AE following late-onset seizures.

Seronegative limbic encephalitis manifesting as subacute amnestic syndrome: a case report and review of the literature

Background

Limbic encephalitis (LE), a variant of autoimmune encephalitis, is inflammation of the limbic system of the brain. The disorder presents with subacute impairment of short-term memory, psychiatric manifestations, confusion and seizures. “Seronegative LE” is a challenging diagnosis in the absence of well-characterized autoantibodies.

Case presentation

A 33-year-old Kuwaiti woman with no relevant past history presented with subacute progressive amnesia of 6-month duration. Magnetic resonance imaging (MRI) showed bilateral hyperintensity of the limbic structures. An extensive workup of the blood and cerebrospinal fluid (CSF) failed to identify paraneoplastic or autoimmune antibodies. The diagnosis of seronegative LE was made, and immunotherapy was initiated, with improvement in cognitive function.

Conclusion

Seronegative LE is a challenging diagnosis. Inability to detect autoantibodies, especially early in the disease course, should not rule out the diagnosis of autoimmune encephalitis. Early diagnosis and treatment with immunotherapy may prevent irreversible brain damage.

When Mind Meets the Brain: Essentials of Well-Coordinated Management of Psychiatric Disorders in Neurological Diseases

BACKGROUND

The management of psychiatric disorders in neurological diseases (PDND) creates special challenges that cannot be adequately addressed by either psychiatry or neurology alone. However, the literature on clinician-friendly recommendations on how to coordinate neurological and psychiatric care is limited.

OBJECTIVE

This narrative review will provide practical instructions on how to efficiently integrate psychiatric and neurological care in inpatient management of PDND.

METHODS

We reviewed articles published as recently as January, 2021 in five electronic databases. We included articles that assessed human care, focused on adults, and examined how to better coordinate care between different medical specialties, particularly, between psychiatry and neurology.

RESULTS

Eighty-four manuscripts were included in this review, of which 23 (27%) discussed general principles of well-coordinated care of PDND in inpatient settings (first part of this review), and 61 (73%) were used to provide recommendations in specific neurological diseases (second part of this review).

CONCLUSIONS

General principles of well-coordinated care of PDND include recommendations for both the primary team (usually neurology) and the consulting team (psychiatry). Primary teams should delineate a specific question, establish roles, and follow up on the recommendations of the consulting team. Consultants should do their independent assessment, be organized and specific in their recommendations, and anticipate potential problems. One of the most important aspect to develop well-coordinated care is the establishment of clear, frank and, preferably oral, communication between the teams. Practical difficulties in the management of PDND include pharmacodynamic and pharmacokinetic interactions as well as mutual dependency between psychiatry and neurology.

Autoimmune encephalitis: proposed recommendations for symptomatic and long-term management

The objective of this paper is to evaluate available evidence for each step in autoimmune encephalitis management and provide expert opinion when evidence is lacking. The paper approaches autoimmune encephalitis as a broad category rather than focusing on individual antibody syndromes. Core authors from the Autoimmune Encephalitis Alliance Clinicians Network reviewed literature and developed the first draft. Where evidence was lacking or controversial, an electronic survey was distributed to all members to solicit individual responses. Sixty-eight members from 17 countries answered the survey. The most popular bridging therapy was oral prednisone taper chosen by 38% of responders while rituximab was the most popular maintenance therapy chosen by 46%. Most responders considered maintenance immunosuppression after a second relapse in patients with neuronal surface antibodies (70%) or seronegative autoimmune encephalitis (61%) as opposed to those with onconeuronal antibodies (29%). Most responders opted to cancer screening for 4 years in patients with neuronal surface antibodies (49%) or limbic encephalitis (46%) as opposed to non-limbic seronegative autoimmune encephalitis (36%). Detailed survey results are presented in the manuscript and a summary of the diagnostic and therapeutic recommendations is presented at the conclusion.

The Efficacy and Safety of Immune Checkpoint Inhibitors in Patients With Cancer and Preexisting Autoimmune Disease

Immune checkpoint inhibitor (ICI) is a revolutionary breakthrough in the field of cancer treatment. Because of dysregulated activation of the immune system, patients with autoimmune disease (AID) are usually excluded from ICI clinical trials. Due to a large number of cancer patients with preexisting AID, the safety and efficacy of ICIs in these patients deserve more attention. This review summarizes and analyzes the data regarding ICI therapy in cancer patients with preexisting AID from 17 published studies. Available data suggests that the efficacy of ICIs in AID patients is comparable to that in the general population, and the incidence of immune-related adverse events (irAEs) is higher but still manageable. It is recommended to administer ICIs with close monitoring of irAEs in patients with a possibly high benefit-risk ratio after a multidisciplinary discussion based on the patient's AID category and severity, the patient's tumor type and prognosis, alternative treatment options, and the patient's intention. Besides, the prevention and management of irAEs in AID patients have been discussed.

Long-term Functional Outcomes and Relapse of Anti-NMDA Receptor Encephalitis: A Cohort Study in Western China

Objective

To study the factors associated with relapse and functional outcomes in patients with anti-NMDA receptor encephalitis in Western China.

Methods

The Outcome of the anti-NMDA receptor Encephalitis Study in Western China was initiated in October 2011 to collect prospective observational data from consecutively enrolled patients with anti-NMDA receptor encephalitis.

Results

We consecutively enrolled 244 patients (median age: 26 years, range: 9–78 years; females: 128 [52.45%]) between October 2011 and September 2019. Fatality occurred in 17 (6.96%) patients, and tumors were found in 38 (15.57%) patients. The median follow-up duration was 40 (6–96) months. Of these patients, 84.8% showed clinical improvements within 4 weeks after immunotherapy, with a median modified Rankin Scale of 2 (interquartile range [IQR]: 2–3), and 80.7% (median: 1, IQR: 0–2) and 85.7% (median: 0, IQR: 0–1) had substantial recovery (i.e., mild or no residual symptoms) at 12 and 24 months, respectively. The overall prognosis was still improving at 42 months after onset. Disturbance of consciousness during the first month was the only independent predictor (OR: 2.91, 95% CI: 1.27–6.65; p = 0.01) of a poor functional neurologic outcome. Overall, 15.9% of the patients had one or multiple relapses, with 82.0% experiencing the first relapse within 24 months and 76.9% experiencing relapses that were less severe than the initial episodes. Relapse-related risk factors included the female sex and delayed treatment (p < 0.05).

Conclusions

Most patients achieved favorable long-term functional outcomes. Some patients experienced one or multiple relapses, especially female patients. Timely immunotherapy at onset may reduce the risk of relapse.

Anti-gamma-aminobutyric acid receptor type A encephalitis: a review

PURPOSE OF REVIEW

To systematically review the clinical features, diagnosis, and management of anti-gamma-aminobutyric acid receptor Type A (GABAA) autoimmune encephalitis with a focus on recent data.

RECENT FINDINGS

In a review of published reports, we identified 50 cases of anti-GABAA receptor encephalitis with clinical features reported. The median age at presentation was 47 years old (range, 2.5 months-88 years old), 64% were adults, 36% were children and it occurred in both males and females. Eight-two percent (41/50) presented with seizures, 72% (36/50) with encephalopathy, and 58% (29/50) with both. Of those presenting with seizures, 42% developed status epilepticus during their disease course. Ninety-six percent (48/50) had MRI results reported, with 83% of these cases having abnormal findings, most commonly multifocal/diffuse cortical and subcortical T2/FLAIR hyperintense lesions without associated gadolinium enhancement. Almost one-third, 28% (14/50), had an associated malignancy detected by the time of diagnosis, 64% (9/14) of which was thymoma. Of 44 patients with outcomes reported, 80% had partial or complete recovery, whereas 20% had poor outcomes including 11% (5/44) who died. Of the 42 patients with type of treatment(s) and outcomes reported, 54% (23/42) received only first-line immunotherapy and 31% (13/42) received first-line and second-line immunotherapy. Receiving a combination of first-line and second-line immunotherapy may be associated with higher likelihood of complete recovery. When follow-up MRIs were reported, all showed improvement, and sometimes complete resolution, of T2/FLAIR hyperintensities.

SUMMARY

Anti-GABAA receptor encephalitis can present across the age spectrum and should be considered in patients who present with rapidly progressive encephalopathy and/or seizures. Brain MRI often shows a distinctive pattern of multifocal cortical and subcortical T2/FLAIR hyperintense lesions, generally not typical of other known central nervous system autoantibody associated encephalitis syndromes. High clinical suspicion and early diagnosis are important given the potential for clinical improvement with immunotherapy.

Autoimmune Encephalitis in Latin America: A Critical Review

Autoimmune encephalitis is an increasingly recognized cause of encephalitis. The majority of case series report patients residing in developed countries in the northern hemisphere. The epidemiologic features of autoimmune encephalitis in Latin America are still unclear. The aim of the study was to perform a review of the clinical presentation of autoimmune encephalitis in Latin America and compare to world literature. References were identified by an in-depth literature search and selected on the basis of relevance to the topic and authors' judgment. We selected clinical studies and case reports published from 2007 to July, 2020 including patients from Latin American countries. Of the 379 patients included, the majority were cases of anti-NMDA receptor encephalitis (93.14%), followed by anti-VGKC-complex encephalitis (N = 17; 4.48%), anti-GAD encephalitis (N = 9; 2.37%), anti-AMPA receptor encephalitis (N = 1; 0.26%), anti-GABA receptor encephalitis (N = 1; 0. 26%), anti-mGluR5 encephalitis (N = 1; 0. 26%), and anti-mGluR1 encephalitis (N = 1; 0. 26%). Reported cases of Anti-NMDA encephalitis in Latin-America had a very slight female predominance, lower prevalence of associated tumors and a lower incidence of extreme delta brush on electroencephalogram. Autoimmune encephalitis is possibly underdiagnosed in underdeveloped countries. Its outcome after treatment, however, appears to be similarly favorable in Latin American patients as has been reported in developed countries based on available case reports and case series. Regional specificities in the manifestation of autoimmune encephalitis could be related to epidemiologic factors, such as the presence of different triggers and different genetic and immunologic background, that need to be studied by future research.

Cerebellar long-term depression and auto-immune target of auto-antibodies: the concept of LTDpathies

There is general agreement that auto-antibodies against ion channels and synaptic machinery proteins can induce limbic encephalitis. In immune-mediated cerebellar ataxias (IMCAs), various synaptic proteins, such as GAD65, voltage-gated Ca channel (VGCC), metabotropic glutamate receptor type 1 (mGluR1), and glutamate receptor delta (GluR delta) are auto-immune targets. Among them, the pathophysiological mechanisms underlying anti-VGCC, anti-mGluR1, and anti-GluR delta antibodies remain unclear. Despite divergent auto-immune and clinical profiles, these subtypes show common clinical features of good prognosis with no or mild cerebellar atrophy in non-paraneoplastic syndrome. The favorable prognosis reflects functional cerebellar disorders without neuronal death. Interestingly, these autoantigens are all involved in molecular cascades for induction of long-term depression (LTD) of synaptic transmissions between parallel fibers (PFs) and Purkinje cells (PCs), a crucial mechanism of synaptic plasticity in the cerebellum. We suggest that anti-VGCC, anti-mGluR1, and anti-GluR delta Abs-associated cerebellar ataxias share one common pathophysiological mechanism: a deregulation in PF-PC LTD, which results in impairment of restoration or maintenance of the internal model and triggers cerebellar ataxias. The novel concept of LTDpathies could lead to improvements in clinical management and treatment of cerebellar patients who show these antibodies.

Infiltration of plasma cells in colorectal adenocarcinoma associated with autoimmune encephalitis

Paraneoplastic autoimmune encephalitis (PAE) represents a group of rare neurological syndromes associated with neoplastic diseases. Here, we report a case that multiple anti‐neuronal antibodies were present in a patient with PAE who developed both small cell lung cancer and colorectal adenocarcinoma. Furthermore, the immunopathological investigation of the colorectal adenocarcinoma revealed the formation of abnormal neuronal antigens and a massive infiltration of plasma cells in the tumor tissue. These findings support the hypothesis that expression of neuronal antigens in neoplasm initiates autoimmune responses in PAE.