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

Clinical analysis of Bornavirus Encephalitis cases demonstrates a small time window for Etiological Diagnostics and treatment attempts, a large case series from Germany 1996-2022

PURPOSE

The emerging zoonotic Borna disease virus 1 (BoDV-1) and the variegated squirrel bornavirus 1 (VSBV-1) cause severe and fatal human encephalitis in Germany. We conducted the first systematic clinical analysis of acute, molecularly confirmed fatal bornavirus encephalitis cases comprising 21 BoDV-1 and four VSBV-1 patients to identify options for better diagnosis and timely treatment.

METHODS

Analyses were based on medical records and, for BoDV-1, on additional medical interviews with patients' relatives.

RESULTS

Disease onset was unspecific, often with fever and headache, inconsistently mixed with early fluctuating neurological symptoms, all rapidly leading to severe encephalopathy and progressive vigilance decline. Very shortly after seeking the first medical advice (median time interval 2 and 0 days for BoDV-1 and VSBV-1, respectively), all except one patient were hospitalised upon manifest neurological symptoms (median 10 and 16 days respectively after general symptom onset). Neurological symptoms varied, always progressing to coma and death. BoDV-1 and VSBV-1 patients required ventilation a median of three and five days, and died a median of 32 and 72 days, after hospitalisation. Death occurred mostly after supportive treatment cessation at different points in time based on poor prognosis. Disease duration therefore showed a wide, incomparable range.

CONCLUSION

The extremely rapid progression is the most obvious clinical characteristic of bornavirus encephalitis and the timeframe for diagnosis and targeted therapy is very short. Therefore, our results demand an early clinical suspicion based on symptomatology, epidemiology, imaging, and laboratory findings, followed by prompt virological testing as a prerequisite for any potentially effective treatment.

Anti-LGI1 Autoimmune Limbic Encephalitis: An Easy-To-Miss Diagnosis

Background

Autoimmune limbic encephalitis (ALE) is a rare inflammatory disorder characterised by a subacute onset, usually within weeks. The presence of multiple neuropsychiatric symptoms such as seizures, short-term memory deficits, anxiety and depression often leads to misdiagnosis as another medical condition, contributing to poor prognosis and reduced long-term survival.

Case description

A 60-year-old man, with no chronic illnesses, presented at the emergency department with daily episodes of palpitations, shivering, piloerection and a sense of impending doom lasting two months. Initially diagnosed with anxiety disorder and treated with venlafaxine 50 mg daily, he showed no improvement and developed memory loss. Hospitalised three months later, he exhibited both temporal and spatial disorientation, along with short-term memory loss. Key findings included elevated serum sedimentation rate, hyponatraemia, increased cerebrospinal fluid (CSF) protein levels and cranial magnetic resonance imaging evidence of bilateral temporal intra-parenchymal lesions, suggesting limbic encephalitis. After ruling out alternative diagnoses, screening of autoantibodies in the CSF was requested, which was positive for anti-LGI1 antibodies. The diagnosis of anti-LGI1 ALE was assumed, and treatment was initiated with significant clinical and imaging improvement.

Conclusions

ALE's broad clinical spectrum contributes to underdiagnosis. Therefore, in patients with new onset of neuropsychiatric symptoms and no prior psychiatric history, ALE should be considered, as prompt diagnosis and treatment are pivotal to achieve a good prognosis.

LEARNING POINTS

Autoimmune limbic encephalitis is a rare inflammatory neurological disease that affects the limbic system particularly the hippocampus, leading to memory impairment and neuropsychiatric symptoms.Due to its wide range of neuropsychiatric symptoms, the diagnosis of autoimmune limbic encephalitis may go unnoticed, leading to misdiagnosis as another medical disorder.Early diagnosis is essential to prevent potential neurological sequelae through appropriate treatment.

An Unusual Case of Limbic Encephalitis Caused by Whipple Disease

Whipple disease (WD), a multisystemic infectious disorder caused by Tropheryma whipplei (T. whipplei), typically presents with gastrointestinal (GI) symptoms such as abdominal pain, diarrhea, GI bleeding, and weight loss. Uncommonly, it can also involve the central nervous system (CNS) and may present with a range of symptoms, including personality changes, dementia, and rhombencephalitis. Prompt antibiotic treatment and careful follow-up are crucial for favorable patient outcomes and a reduction in morbidity and mortality. In this case, we describe a 46-year-old male with primary CNS-WD and discuss the symptomatic manifestations, diagnostic findings, differential diagnosis, and management. This patient initially presented with arthritic complaints and, over a five-year period, developed progressive neurocognitive symptoms, including anxiety, panic attacks, retrograde amnesia, personality changes, aphasia, anhedonia, dysarthria, and rapidly progressive dementia. Magnetic resonance imaging (MRI) revealed symmetric T2 fluid-attenuated inversion recovery (FLAIR) hyperintensities in the bilateral medial temporal lobes, hippocampi, and hypothalamus. A lumbar puncture (LP) showed mild pleocytosis and elevated protein, with no autoimmune or paraneoplastic causes. Temporal lobe biopsy revealed rod-like structures, and T. whipplei DNA was confirmed by polymerase chain reaction (PCR). This case underscores the importance of maintaining a high index of suspicion for WD in patients presenting with atypical symptoms with rapidly progressive dementia, as early detection and management are key to circumventing irreversible neurological damage and death.

Sudden unexpected death in epilepsy and ictal asystole in patients with autoimmune encephalitis: a systematic review

OBJECTIVE

As autoimmune encephalitis (AE) often involves the mesial temporal structures which are known to be involved in both sudden unexpected death in epilepsy (SUDEP) and ictal asystole (IA), it may represent a good model to study the physiopathology of these phenomena. Herein, we systematically reviewed the occurrence of SUDEP and IA in AE.

METHODS

We searched 4 databases (MEDLINE, Scopus, Embase, and Web of Science) for studies published between database inception and December 20, 2022, according to the PRISMA guidelines. We selected articles reporting cases of definite/probable/possible/near-SUDEP or IA in patients with possible/definite AE, or with histopathological signs of AE.

RESULTS

Of 230 records assessed, we included 11 cases: 7 SUDEP/near-SUDEP and 4 IA. All patients with IA were female. The median age at AE onset was 30 years (range: 15-65), and the median delay between AE onset and SUDEP was 11 months; 0.9 months for IA. All the patients presented new-onset seizures, and 10/11 also manifested psychiatric, cognitive, or amnesic disorders. In patients with SUDEP, 2/7 were antibody-positive (1 anti-LGI1, 1 anti-GABABR); all IA cases were antibody-positive (3 anti-NMDAR, 1 anti-GAD65). Six patients received steroid bolus, 3 intravenous immunoglobulin, and 3 plasmapheresis. A pacemaker was implanted in 3 patients with IA. The 6 survivors improved after treatment.

DISCUSSION

SUDEP and IA can be linked to AE, suggesting a role of the limbic system in their pathogenesis. IA tends to manifest in female patients with temporal lobe seizures early in AE, highlighting the importance of early diagnosis and treatment.

An Unusual Case of GRIN2A Mutation Presenting as Progressive Limbic Encephalopathy in an Adult

The glutamate ionotropic receptor NMDA (N-methyl-D-aspartate) type subunit 2A gene (GRIN2A) encodes the GluN2A subunit of NMDA receptors, which are essential for synaptic plasticity and memory consolidation. Mutations in GRIN2A can disrupt these processes, often affecting the pediatric population and causing various neurological disorders characterized by epilepsy, intellectual disability, and aphasia, among other neuropsychiatric findings. We report an unusual presentation of adult-onset GRIN2A mutation-associated progressive limbic encephalopathy (LE), characterized by rapidly progressive cortical atrophy, seizures, aphasia, and neuropsychiatric abnormalities, which ultimately led to the patient's sudden demise. Further research into GRIN2A mutations will improve our understanding of such presentations, guiding enhancements in diagnostic methods and therapeutic approaches.

Paraneoplastic neurological syndromes of small cell lung cancer

Purpose

This article reviews the relevant literature on paraneoplastic neurological syndromes of small cell lung cancer and discusses the clinical presentation, pathophysiology, and diagnosis of these syndromes. It also includes a summary of the current treatment options for the management of them.

Views

Paraneoplastic syndromes are a group of signs and symptoms that develop due to cancer in a remote site, mainly triggered by an autoantibody produced by the tissues involved or lymphocytes during anti-cancer defense. Among the cancers associated with paraneoplastic syndromes, lung cancers are the most common type, with small cell lung cancer being the most common subtype. The most common antibody associated with paraneoplastic syndromes is anti-Hu. Neurological and neuroendocrine syndromes comprise the majority of small cell lung cancer-related paraneoplastic syndromes. Classical paraneoplastic neurological syndromes include inappropriate antidiuretic hormone secretion, Cushing's syndrome, myasthenia gravis, Lambert-Eaton myasthenic syndrome, limbic encephalitis, paraneoplastic cerebellar degeneration, opsoclonus myoclonus ataxia, sensory neuropathy, and chorea.

Conclusions

Antibodies mediate paraneoplastic syndromes, and antibody detection is a crucial part of diagnosing these entities. Managing the underlying tumor is the best treatment approach for most paraneoplastic syndromes. Therefore, early diagnosis of small cell lung cancer may significantly improve the prognosis of paraneoplastic syndromes associated with it.

General features, pathogenesis, and laboratory diagnostics of autoimmune encephalitis

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

The role of the CD8+ T cell compartment in ageing and neurodegenerative disorders

CD8+ lymphocytes are adaptive immunity cells with the particular function to directly kill the target cell following antigen recognition in the context of MHC class I. In addition, CD8+ T cells may release pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), and a plethora of other cytokines and chemoattractants modulating immune and inflammatory responses. A role for CD8+ T cells has been suggested in aging and several diseases of the central nervous system (CNS), including Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, limbic encephalitis-induced temporal lobe epilepsy and Susac syndrome. Here we discuss the phenotypic and functional alterations of CD8+ T cell compartment during these conditions, highlighting similarities and differences between CNS disorders. Particularly, we describe the pathological changes in CD8+ T cell memory phenotypes emphasizing the role of senescence and exhaustion in promoting neuroinflammation and neurodegeneration. We also discuss the relevance of trafficking molecules such as selectins, mucins and integrins controlling the extravasation of CD8+ T cells into the CNS and promoting disease development. Finally, we discuss how CD8+ T cells may induce CNS tissue damage leading to neurodegeneration and suggest that targeting detrimental CD8+ T cells functions may have therapeutic effect in CNS disorders.

Autoimmune Encephalitis Associated with Anti-N-methyl-D-aspartate Receptor and Anti-Hu Antibodies Successfully Treated with Carboplatin and Etoposide for Small-cell Lung Cancer

The coexistence of multiple autoantibodies associated with autoimmune encephalitis (AE) is rare. A 63-year-old woman developed psychosis and consciousness disorder. Her cerebrospinal fluid was positive for anti-N-methyl-D-aspartate receptor antibodies, and her serum was positive for anti-Hu antibodies. Enhanced computed tomography revealed a mass in the right pulmonary hilum. AE complicated with small-cell lung cancer was diagnosed. Immunotherapy (steroid therapy and intravenous immunoglobulin) and four courses of carboplatin-etoposide chemotherapy were required to improve her neurological symptoms. When the coexistence of multiple antibodies is detected, despite its rarity, aggressive detection and treatment of any underlying malignancy may be recommended.

Post-COVID-19 Vaccine Limbic Encephalitis: A Case Report

Limbic encephalitis (LE) diagnosis can be challenging due to its broad spectrum of clinical presentation and variety of causes. The most commonly known causes include paraneoplastic and autoimmune, but they can also occur post-vaccine. Since 2020, many people worldwide have received the coronavirus disease 2019 (COVID‐19) vaccine after FDA approval. Mild self-limited neurological adverse reactions, including headache and dizziness, were reported post-vaccine. However, emerging few neurological severe events, including encephalitis, have also been reported. Herein, we present a case of a middle-aged female who presented with seizures after two days of receiving the second dose of the Moderna COVID-19 vaccine. A diagnosis of limbic encephalitis was made based on head MRI findings. It was treated with immunosuppressive agents and responded well with no additional neurological sequelae. This case is unique as it highlights a possible association between limbic encephalitis and the COVID-19 vaccine.

Inflammatory Markers in Substance Use and Mood Disorders: A Neuroimaging Perspective

Chronic exposure to addictive drugs in substance use disorders and stressors in mood disorders render the brain more vulnerable to inflammation. Inflammation in the brain, or neuroinflammation, is characterized by gliosis, microglial activation, and sustained release of cytokines, chemokines, and pro-inflammatory factors compromising the permeability of the blood-brain barrier. There is increased curiosity in understanding how substance misuse and/or repeated stress exposure affect inflammation and contribute to abnormal neuronal activity, altered neuroplasticity, and impaired cognitive control, which eventually promote compulsive drug-use behaviors and worsen mood disorders. This review will emphasize human imaging studies to explore the link between brain function and peripheral markers of inflammation in substance use disorders and mood disorders.