Advances in Autoimmune Epilepsy Associated with Antibodies, Their Potential Pathogenic Molecular Mechanisms, and Current Recommended Immunotherapies

Low triiodothyronine (T3) levels predict worse outcomes in autoimmune encephalitis-A meta-analysis of current literature

INTRODUCTION

An unusual association between thyroid dysfunction and autoimmune encephalitis (AE) was noticed when patients presented with low free triiodothyronine (fT3) levels and antithyroid antibodies. We conducted a meta-analysis to investigate whether thyroid dysfunction, that is, lower fT3 levels are associated with worsening clinical manifestations and prognosis in patients with AE.

METHODS

Literature search of five electronic databases was performed till April 5, 2023. Inclusion criteria were as follows: Observational studies reporting patients with all subtypes of AE and assessing thyroid dysfunction categorized as low fT3 and non-low fT3. Primary endpoints included modified Rankin scale (mRS) at admission, abnormal magnetic resonance imaging, length of stay, seizures, and consciousness declination.

RESULTS

Comprehensive literature search resulted in 5127 studies. After duplicate removal and full-text screening, six observational studies were included in this analysis. Patients with low fT3 were 2.95 times more likely to experience consciousness declination (p = .0003), had higher mRS at admission (p < .00001), had 3.14 times increased chances of having a tumor (p = .003), were 3.88 times more likely to experience central hypoventilation, and were 2.36 times more likely to have positivity for antithyroid antibodies (p = .009) as compared to patients with non-low fT3.

CONCLUSION

The findings of our study suggest that low fT3 levels might be related to a more severe disease state, implying the significance of thyroid hormones in AE pathogenesis. This finding is crucial in not only improving the early diagnosis of severe AE but also in the efficient management of the disease.

Utilization of APE2 and RITE2 scores in autoimmune encephalitis patients with seizures

PURPOSE

Immune-mediated seizures are rare but are increasingly recognized as an etiology of seizures resistant to anti-seizure medications (ASMs). Antibody Prevalence in Epilepsy 2 (APE2) and Response to Immunotherapy in Epilepsy 2 (RITE2) scores were developed recently to identify patients who may be seropositive for serum central nervous system (CNS) specific antibodies (Ab) and may benefit from immunotherapy (Dubey et al. 2018). The goal of this study was to apply APE2 and RITE2 scores to an independent cohort of patients with seizures secondary to autoimmune encephalitis (AE) and to further verify the sensitivity and specificity of the scores.

PRINCIPAL RESULTS

We conducted a retrospective study at Stanford University Hospital between 2008 and 2021 and included patients who had acute seizures and AE using diagnostic criteria from Graus (n = 34 definite AE, 10 probable AE, and 12 possible AE) (Graus et al. 2016). Patients were excluded if they did not have a serum Ab panel investigated or had alternate diagnoses (n = 55). APE2 and RITE2 scores were calculated based on clinical and diagnostic data (n = 56). Serum Ab were positive in 73 % of patients, in which 63 % cases carried CNS specific Ab. An APE2 score ≥ 4 had a sensitivity of 97 % and specificity of 14 % to predict a positive serum CNS specific Ab. A RITE2 score ≥ 7 had a sensitivity of 93 % and specificity of 60 % to predict seizure responsiveness to immunotherapy.

CONCLUSION

APE2 and RITE2 scores had high sensitivities but low specificities to predict seropositivity and seizure responsiveness to immunotherapy in patients with autoimmune encephalitis with seizures.

Autoimmune Encephalitis-A Multifaceted Pathology

Autoimmune encephalitis is a complex and multifaceted pathology that involves immune-mediated inflammation of the brain. It is characterized by the body's immune system attacking the brain tissue, leading to a cascade of inflammatory processes. What makes autoimmune encephalitis vast is the wide range of causes, mechanisms, clinical presentations, and diagnostic challenges associated with the condition. The clinical presentations of autoimmune encephalitis are broad and can mimic other neurological disorders, making it a challenging differential diagnosis. This diverse clinical presentation can overlap with other conditions, making it crucial for healthcare professionals to maintain a high level of suspicion for autoimmune encephalitis when evaluating patients. The diagnostic challenges associated with autoimmune encephalitis further contribute to its vastness. Due to the variable nature of the condition, there is no definitive diagnostic test that can confirm autoimmune encephalitis in all cases. In this context, personalized patient management is crucial for achieving favorable outcomes. Each patient's treatment plan should be tailored to their specific clinical presentation, underlying cause, and immune response. Our objective is to raise awareness about the frequent yet underdiagnosed nature of autoimmune encephalitis by sharing five cases we encountered, along with a brief literature review.

Autoimmune Encephalitis: A Physician’s Guide to the Clinical Spectrum Diagnosis and Management

The rapidly expanding spectrum of autoimmune encephalitis in the last fifteen years is largely due to ongoing discovery of many neuronal autoantibodies. The diagnosis of autoimmune encephalitis can be challenging due to the wide spectrum of clinical presentations, prevalence of psychiatric features that mimic primary psychiatric illnesses, frequent absence of diagnostic abnormalities on conventional brain MR-imaging, non-specific findings on EEG testing, and the lack of identified IgG class neuronal autoantibodies in blood or CSF in a subgroup of patients. Early recognition and treatment are paramount to improve outcomes and achieve complete recovery from these debilitating, occasionally life threatening, disorders. This review is aimed to provide primary care physicians and hospitalists who, together with neurologist and psychiatrists, are often the first port of call for individuals presenting with new-onset neuropsychiatric symptoms, with up-to-date data and evidence-based approach to the diagnosis and management of individuals with neuropsychiatric disorders of suspected autoimmune origin.

Cytokines as a marker of central nervous system autoantibody associated epilepsy

OBJECTIVE

Autoantibodies to central nervous system (CNS) antigens are increasingly identified in patients with epilepsy. Alterations in cytokines and chemokines have also been demonstrated in epilepsy, but this has not been explored in subjects with autoantibodies. If antibody positive and antibody negative subjects show a difference in immune activation, as measured by cytokine levels, this could improve diagnostic and therapeutic approaches, and provide insights into the underlying pathophysiology. We aimed to evaluate serum and CSF cytokines and chemokines in patients with and without autoantibody positivity to identify any differences between the two groups.

METHODS

We studied participants who had undergone serum and CSF testing for CNS autoantibodies, as part of their clinical evaluation. Cases were classified as antibody positive or antibody negative for comparison. Stored CSF and sera were analysed for cytokine and chemokine concentrations.

RESULTS

25 participants underwent testing. 8 were antibody positive, 17 were antibody negative. Significant elevations in the mean concentration of IL-13 and RANTES in CSF were found in the antibody positive cases and significant elevation of CSF VEGF was found in the antibody negative cases. Significant elevations in the mean concentrations of serum TNFβ, INFγ, bNGF, IL-8, and IL-12 were seen in the antibody negative group, and there was poor correlation between the majority of serum and CSF concentrations.

SIGNIFICANCE

Measurement of cytokines and chemokines such as IL-13 and RANTES could be useful in diagnosis of autoimmune associated epilepsy. Such markers might also guide targeted immunotherapy to improve seizure control and provide insights into the underlying pathophysiology of epilepsy associated with CNS autoantibodies.

Genetic or Autoimmune: POLG-Related Epilepsy Initially Treated as an Autoimmune Encephalitis, a Case Report

Hospital neurologists participate at the forefront of managing fulminant acute and subacute onset epilepsy, frequently attributed to autoimmune encephalitis (AE). As the recognition of antibody-mediated AE grows, there is a growing number of patients who are treated as antibody-negative AE. While antibody-negative autoimmune processes should be considered in the setting of acute and subacute onset of fulminant epilepsy, other causes must be considered before subjecting patients to long-term immunomodulatory treatments and other potential therapeutic toxicities. We present the case of a previously healthy young man who presented with new-onset refractory seizures treated with escalating doses of anti-epileptic drugs as well as immunosuppression for presumed autoimmune epilepsy. He developed valproic acid induced hepatotoxicity requiring liver transplantation and was later found to have a POLG mutation. We discuss the presentation of POLG mutations as well as the diagnosis of seronegative autoimmune encephalitis. We highlight the need for a broad differential when evaluating new onset refractory seizures in an otherwise healthy person.

Anti-Hu-related epilepsy diagnosed after surgical management

Autoimmune epilepsy (AE) refers to epilepsy mediated by autoantibodies or immune cells, and a large proportion of drug-resistant epilepsy cases are classified as AE. AE lacks standardized management guidelines. At present, little research has been conducted on the effectiveness of surgical treatment of AE. This paper reports a patient whose surgical treatment was ineffective before AE was diagnosed and who improved after immunotherapy. A literature review was conducted to examine the progress of surgical treatment of epilepsy, the relationship of temporal lobe epilepsy to neuronal antibodies, surgical and prognostic factors, research progress on the anti-Hu antibody, and treatment of autoimmune encephalitis to provide a clinical reference.

Relevance of Surface Neuronal Protein Autoantibodies as Biomarkers in Seizure-Associated Disorders

The detection of neuronal surface protein autoantibody-related disorders has contributed to several changes in our understanding of central nervous system autoimmunity. The clinical presentation of these disorders may be associated (or not) with tumors, and often patients develop an inexplicable onset of epilepsy, catatonic or autistic features, or memory and cognitive dysfunctions. The autoantigens in such cases have critical roles in synaptic transmission and plasticity, memory function, and process learning. For months, patients with such antibodies may be comatose or encephalopathic and yet completely recover with palliative care and immunotherapies. This paper reviews several targets of neuronal antibodies as biomarkers in seizure disorders, focusing mainly on autoantibodies, which target the extracellular domains of membrane proteins, namely leucine-rich glioma-inactivated-1 (LGI1), contactin-associated protein-like 2 (CASPR2), the N-methyl-D-aspartate receptor (NMDAR), γ-aminobutyric acid receptor-B (GABA_BR), the glycine receptor (GlyR), and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). In order to restore health status, limit hospitalization, and optimize results, testing these antibodies should be done locally, using internationally certified procedures for a precise and rapid diagnosis, with the possibility of initiating therapy as soon as possible.

Identifying the culprits in neurological autoimmune diseases

The target organ of neurological autoimmune diseases (NADs) is the central or peripheral nervous system. Multiple sclerosis (MS) is the most common NAD, whereas Guillain-Barré syndrome (GBS), myasthenia gravis (MG), and neuromyelitis optica (NMO) are less common NADs, but the incidence of these diseases has increased exponentially in the last few years. The identification of a specific culprit in NADs is challenging since a myriad of triggering factors interplay with each other to cause an autoimmune response. Among the factors that have been associated with NADs are genetic susceptibility, epigenetic mechanisms, and environmental factors such as infection, microbiota, vitamins, etc. This review focuses on the most studied culprits as well as the mechanisms used by these to trigger NADs.

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Neurological autoimmune diseases are caused by a complex interaction between genes, environmental factors, and epigenetic deregulation.

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Infectious agents can cause an autoimmune reaction to myelin epitopes through molecular mimicry and/or bystander activation.

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Gut microbiota dysbiosis contributes to neurological autoimmune diseases.

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Smoking increases the risk of NADs through inflammatory signaling pathways, oxidative stress, and Th17 differentiation.

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Deficiency in vitamin D favors NAD development through direct damage to the central and peripheral nervous system.

Protein biomarkers of epileptogenicity after traumatic brain injury

Traumatic brain injury (TBI) is a major risk factor for acquired epilepsy. Post-traumatic epilepsy (PTE) develops over time in up to 50% of patients with severe TBI. PTE is mostly unresponsive to traditional anti-seizure treatments suggesting distinct, injury-induced pathomechanisms in the development of this condition. Moderate and severe TBIs cause significant tissue damage, bleeding, neuron and glia death, as well as axonal, vascular, and metabolic abnormalities. These changes trigger a complex biological response aimed at curtailing the physical damage and restoring homeostasis and functionality. Although a positive correlation exists between the type and severity of TBI and PTE, there is only an incomplete understanding of the time-dependent sequelae of TBI pathobiologies and their role in epileptogenesis. Determining the temporal profile of protein biomarkers in the blood (serum or plasma) and cerebrospinal fluid (CSF) can help to identify pathobiologies underlying the development of PTE, high-risk individuals, and disease modifying therapies. Here we review the pathobiological sequelae of TBI in the context of blood- and CSF-based protein biomarkers, their potential role in epileptogenesis, and discuss future directions aimed at improving the diagnosis and treatment of PTE.

Precision in pediatric epilepsy

Epilepsy in infants and children is one of the most common and devastating neurological disorders. In the past, we had a limited understanding of the causes of epilepsy in pediatric patients, so we treated pediatric epilepsy according to seizure type. Now with new tools and tests, we are entering the age of precision medicine in pediatric epilepsy. In this review, we use the new etiological classification system proposed by the International League Against Epilepsy to review the advances in the diagnosis of pediatric epilepsy, describe new tools to identify seizure foci for epilepsy surgery, and define treatable epilepsy syndromes.