Paraneoplastic encephalitis.

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

Case report: Successful treatment of an anti-D2R and DPPX antibody-associated autoimmune encephalitis patient with high-dose methylprednisolone and intravenous immunoglobulin.

Background: Autoimmune encephalitis is a neurological condition caused by abnormal immune responses, manifesting as cognitive impairments, behavioral abnormalities, and seizures. Its diagnosis depends on the detecting neuronal surface antibodies in serum or cerebrospinal fluid. Despite recent advances in understanding, clinical recognition remains challenging, especially with rare antibodies such as anti-dopamine D2 receptor (D2R) and anti-dipeptidyl-peptidase-like protein 6 (DPPX) antibodies. Delayed diagnosis can lead to severe complications. This case presentation emphasizes the diagnostic intricacies and effective treatment of the anti-D2R and DPPX antibody-associated autoimmune encephalitis. Case description: The patient presented with a 3-day history of fatigue and limb soreness followed by a 3-h episode of confusion and limb convulsions. Upon admission to our facility, the initial diagnosis included status epilepticus, aspiration pneumonia, metabolic acidosis, respiratory alkalosis, and suspected encephalitis. Despite receiving antiepileptic, anti-infection, and antivirus therapy, the patient's condition deteriorated. Both computed tomography (CT) scan and magnetic resonance imaging (MRI) of the brain showed no significant abnormalities. No pathogen was identified in the cerebrospinal fluid (CSF). However, further CSF and serum examination revealed positive results of anti-D2R and anti-DPPX antibodies, confirming a diagnosis of anti-D2R and DPPX antibody-associated autoimmune encephalitis. The patient underwent a comprehensive treatment regimen, including high-dose methylprednisolone pulse therapy combined with intravenous immunoglobulin (IVIG), antiviral and anti-infection treatments, and antiepileptic medications. Significant clinical improvement was observed, and by the 18th day of admission, the patient was stable and coherent. Conclusions: The current patient represents the first reported case of double-positive autoimmune encephalitis for anti-D2R and DPPX antibodies, with epilepsy as a prominent feature. High-dose methylprednisolone pulse therapy combined with IVIG has shown significant safety and efficacy in treating anti-D2R and DPPX antibody-positive autoimmune encephalitis-associated epilepsy.

Evaluation of pathogen from the FilmArray meningitis/encephalitis panel and recommendations on atypical findings.

BACKGROUND: Infectious meningoencephalitis is a potentially fatal clinical condition that causes inflammation of the central nervous system secondary to the installation of different microorganisms. The FilmArray meningitis/encephalitis panel allows the simultaneous detection of 14 pathogens with results in about one hour. OBJECTIVE: This study is based on retrospectively evaluating the implementation of the FilmArray meningitis/encephalitis panel in a hospital environment, highlighting the general results and, especially, analyzing the consistency of the test results against the clinical and laboratory conditions of the patients. METHODS: Data were collected through the results reported by the BioFire FilmArray system software from the meningitis/encephalitis panel. The correlated laboratory tests used in our analysis, when available, included biochemical, cytological, direct and indirect microbiological tests. RESULTS: In the analyzed period, there were 496 samples with released results. Of the total of 496 samples analyzed, 88 (17.75%) were considered positive, and 90 pathogens were detected, and in 2 of these (2.27%) there was co-detection of pathogens. Viruses were the agents most frequently found within the total number of pathogens detected. Of the 496 proven samples, 20 (4.03%) were repeated, 5 of which were repeated due to invalid results, 6 due to the detection of multiple pathogens and 9 due to disagreement between the panel results and the other laboratory tests and/or divergence of the clinical-epidemiological picture. Of these 20 repeated samples, only 4 of them (20%) maintained the original result after repeating the test, with 16 (80%) being non-reproducible. The main factor related to the disagreement of these 16 samples during retesting was the detection of bacterial agents without any relationship with other laboratory tests or with the patients' clinical condition. CONCLUSION: In our study, simply reproducing tests with atypical results from the FilmArray meningitis/encephalitis panel proved, in most cases, effective and sufficient for interpreting these results.

ANTECEDENTES: A meningoencefalite infecciosa é uma condição clínica potencialmente fatal que causa inflamação do sistema nervoso central secundária à instalação de diversos microrganismos. O painel de meningite/encefalite FilmArray permite a detecção simultânea de 14 patógenos, com resultados em cerca de uma hora. OBJETIVO: Este estudo baseia-se em avaliar retrospectivamente a implementação do painel de meningite/encefalite FilmArray em ambiente hospitalar, destacando os resultados gerais e, principalmente, analisando a consistência dos resultados do teste frente às condições clínicas e laboratoriais dos pacientes. MéTODOS: Os dados foram coletados por meio dos resultados relatados pelo software do sistema BioFire FilmArray do painel de meningite/encefalite. Os exames laboratoriais correlacionados utilizados em nossa análise, quando disponíveis, incluíram exames bioquímicos, citológicos, microbiológicos diretos e indiretos. RESULTADOS: No período analisado, foram 496 amostras com resultados divulgados. Do total de 496 amostras analisadas, 88 (17,75%) foram consideradas positivas e 90 patógenos foram detectados, sendo que em duas destas (2,27%) houve codetecção de patógenos. Os vírus foram os agentes mais frequentemente encontrados dentro do total de patógenos detectados. Das 496 amostras analisadas, 20 (4,03%) foram repetidas, sendo 5 repetidas por resultado inválido, 6 pela detecção de múltiplos patógenos e 9 por discordância dos resultados do painel com os demais exames laboratoriais e/ou divergência do quadro clínico-epidemiológico. Destas 20 amostras repetidas, apenas 4 delas (20%) mantiveram o resultado original após a repetição do teste, sendo 16 (80%) não reprodutíveis. O principal fator relacionado à discordância destas 16 amostras na retestagem foi a detecção de agentes bacterianos sem qualquer relação com os demais exames laboratoriais ou com o quadro clínico dos pacientes. CONCLUSãO: Em nosso estudo, a simples repetição dos testes com resultados atípicos do painel de meningite/encefalite FilmArray mostrou-se, na maior dos casos, efetiva e suficiente para a interpretação destes achados.

Encephalitis in HIV-negative immunodeficient patients: a prospective multicentre study, France, 2016 to 2019.

BackgroundData on infectious encephalitis in immunodeficient (ID) individuals are scarce. This population may present with atypical clinical symptoms, be infected by uncommon pathogens and develop poor outcomes.AimWe aimed to describe the epidemiology of infectious encephalitis among HIV-negative ID patients.MethodsPatients from the ENCEIF (Etude Nationale de Cohorte des Encéphalites Infectieuses en France) prospective cohort meeting criteria for infectious encephalitis between January 2016 and December 2019 were included. We compared clinical presentation, magnetic resonance imaging (MRI) results, biological results, infection causes and outcome of ID patients with immunocompetent (IC) patients using Pearson's chi-squared test and Student's t-test. We carried out logistic regression to assess the role of immunodeficiency as risk factor for poor outcome.ResultsID patients (n = 58) were older (mean 72 vs 59 years), had higher prevalence of diabetes (26% vs 12%), pre-existing neurological disorders (12% vs 5%) and higher case-fatality rate (23.6% vs 5.6%) compared to IC patients (n = 436). Varicella zoster virus was the primary cause of encephalitis in ID patients (this aetiology was more frequent in ID (25.9%) than in IC patients (11.5%)), with herpes simplex virus second (22.4% in ID patients vs 27.3% in IC patients). Immunodeficiency was an independent risk factor for death or major sequelae (odds ratio: 3.41, 95%CI: 1.70-6.85).ConclusionsVaricella zoster virus is the most frequent cause of infectious encephalitis in ID patients. Immunodeficiency is a major risk factor for poor outcome. ID encephalitis patients should benefit from stringent investigation of cause and early empiric treatment.

Aetiology and Prognosis of Encephalitis in Korean Children: A Retrospective Single-Centre Study, 2005-2020.

PURPOSE: Encephalitis is a heterogeneous syndrome that occurs in childhood and is not rare. However, epidemiological studies of encephalitis based on the International Encephalitis Consortium (ICS) and expert recommendations are lacking. We investigated the aetiology and prognosis of encephalitis in Korean children. MATERIALS AND METHODS: This retrospective study included children aged <19 years hospitalised for encephalitis at Severance Children's Hospital between 2005 and 2020. The 2013 ICS criteria were used to diagnose encephalitis, and causality was classified according to the site from which the specimen was obtained. Neurological sequelae were categorised using the modified Rankin Scale (mRS) score. RESULTS: In total, 551 children were included, with 7% classified as possible, 77% as probable, and 15% as proven cases. A cause was identified in 42% of the cases (n=222), with viruses being the most common (42%), followed by bacteria (38%) and autoimmune encephalitis (12%). In cases of proven/probable encephalitis (n=65), bacteria accounted for 52%, followed by viruses (25%) and autoimmune encephalitis (22%). In cases with a single pathogen, the anti-N-methyl-D-aspartate receptor autoantibody (n=14) was the most common, followed by Group B streptococcus (n=13), herpes simplex virus (n=11), enterovirus (n=4), and others. Approximately 37% of patients had severe sequelae (mRS score ≥3) at discharge, which decreased to 31% 6 months after discharge. CONCLUSION: This large-scale study showed that autoimmune and infectious causes accounted for a significant proportion of encephalitis in Korean children. Further studies are needed to determine whether early targeted treatment following early diagnosis leads to a favourable prognosis in these populations.

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.

Case Report: Autoimmune encephalitis and other neurological syndromes with rare neuronal surface antibody in children after hematopoietic stem cell transplantation.

Introduction: Neuronal surface antibody syndromes (NSAS) encompass a growing set of autoimmune neurological disorders, with their predominant clinical presentation being autoimmune encephalitis (AE). The most extensively documented form within NSAS is anti-N-methyl-D-aspartate receptor (NMDAR) autoimmunity. In contrast, other NSAS, such as anti-metabotropic glutamate receptor-5 (mGluR5) autoimmunity, are less common and less comprehensively characterized, particularly in pediatric cases. Case description: In this instance, we present the case of a 7-year-old girl who exhibited abnormal behaviors following hematopoietic stem cell transplantation (HSCT). She received a diagnosis of anti-mGluR5 AE, and her Electroencephalogram (EEG) displayed an increased number of generalized slow waves during wakefulness. Treatment involved intravenous administration of gamma globulin and methylprednisolone, followed by oral prednisone tablets. Levetiracetam was introduced as an antiepileptic therapy during the pulse steroid therapy. Notably, the abnormal behaviors exhibited significant improvement after treatment. Conclusions: To the best of our knowledge, this is the first report of rare pediatric NSAS involving anti-mGluR5 AE following HSCT. Enhancing our understanding and characterization of this condition may facilitate its recognition and treatment in children. Serum antibody testing could enable early identification and treatment of anti-mGluR5 AE.

Autoimmune GFAP astrocytopathy after viral encephalitis: a case report of bimodal overlapping encephalitis.

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a treatable autoimmune disorder affecting the central nervous system. Despite extensive research, the exact etiology and pathogenesis of this condition remain unclear. In recent years, autoimmune encephalitis (AE) after viral encephalitis (VE) has gathered significant attention. Here, we present a case report of autoimmune GFAP astrocytopathy after VE in a 43-year-old Asian male with a history of oral and labial herpes. The patient presented with high-grade fever, headache, urinary retention, unresponsiveness, and apathy. Elevated levels of protein and GFAP-IgG were observed in the cerebrospinal fluid (CSF), and enhanced brain magnetic resonance imaging (MRI) revealed linear enhancement oriented radially to the ventricles. Treatment with intravenous immunoglobulin (IVIG) resulted in symptom relief, reduced lesion enhancement, and decreased protein levels. This case report highlights bimodal encephalitis with no discernible interval between VE and autoimmune GFAP astrocytopathy, which poses diagnostic challenges. Notably, autoimmune GFAP astrocytopathy is a novel form of autoimmune encephalitis, and its treatment lacks sufficient clinical experience. Intriguingly, our patient demonstrated sensitivity to IVIG, a treatment that differed from past reports. Therefore, further exploration of treatment strategies for this condition is warranted.

Clinical and radiological features of a case of primary encephalitis induced by SARS-CoV-2 omicron variant infection: A case report.

RATIONALE: In 2022, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron spread widely around the world. In the context of most literature reporting weakened virulence of the virus, immunocompromised patients who have not been vaccinated should be vigilant for the development of encephalitis following SARS-CoV-2 infection. PATIENT CONCERNS: A 58-year-old male patient with immunodeficiency presented with respiratory and psychiatric symptoms after contracting SARS-CoV-2 Omicron variant. DIAGNOSES: The patient was diagnosed with coronavirus disease 2019 infection and associated acute primary encephalitis. INTERVENTIONS: The patient was received comprehensive treatment including Azvudine antiviral therapy, immunoglobulin infusion, and methylprednisolone anti-inflammatory therapy. OUTCOMES: The patient's condition improved and he was discharged smoothly. One month after discharge, the patient returned for follow-up, and the occipital lobe still had a few slow waves on electroencephalogram, but the patient reported no seizure events since discharge. LESSONS: During the prevalence of the SARS-CoV-2 Omicron variant, we believe that it is still necessary to be vigilant about immunocompromised patients developing encephalitis. Early use of cranial magnetic resonance imaging as a diagnostic assistance is conducive to early diagnosis and treatment of patients.

Sjogren's syndrome related autoimmune encephalopathy presenting as depression and involuntary agitation in a 15-year-old girl: a case report.

Introduction: Sjogren's syndrome is an autoimmune disease that commonly involves exocrinopathy. Although studies have reported psychiatric manifestations resulting from Sjogren's syndrome, few studies have focused on such manifestations in pediatric patients. Herein, we present a case of an adolescent girl with depression and involuntary self-harm behaviors related to Sjogren's syndrome with central nervous system involvement. Case presentation: A 15-year-old girl, with an underlying history of epilepsy, developed depressive symptoms of a year's duration, accompanied by three seizure episodes and involuntary self-harm behaviors. The self-harm behaviors, which included head banging and arm scratching, were sudden onset, involuntary, and unable to be recalled afterwards. After admission to our ward, the patient was positive for serum antinuclear antibodies and Schirmer's test. Moreover, 24-hour electroencephalography revealed epileptiform discharges during the mood swing episodes. Positive findings for antinuclear antibodies and anti-SSA antibodies in both serum and cerebrospinal fluid, suggested central nervous system involvement in Sjogren's syndrome. After rituximab treatment, her mood became euthymic, and her involuntary self-harm behaviors ceased. Conclusion: Central nervous system involvement leading to psychiatric presentations has rarely been reported in adolescents with Sjogren's syndrome. When treating adolescent patients with involuntary self-harm behaviors and neurological symptoms, it is crucial to consider autoimmune encephalitis related to Sjogren's syndrome in the differential diagnosis.

Neurological Manifestations of Coronavirus Disease 2019 and Mpox in Pediatric Patients and Their Management: A State-of-the-Art Systematic Review.

BACKGROUND: There is an increasing number of cases being reported of neurological manifestations of Coronavirus disease 2019 (COVID-19) infection and Monkeypox (Mpox), both during the course of the infection and as a presenting symptom. We aim to review the neurological manifestations of COVID-19 and monkeypox in pediatric patients and their management. METHODS: We conducted a systematic review that included cohort studies and case series or reports involving a pediatric population of patients with a confirmed COVID-19 or Mpox infection and their neurological manifestations. We searched the following electronic databases: PubMed, EMBASE, and Scopus. RESULTS: From 1136 articles identified, 127 studies were included. Headache, stroke, Guillain-Barré syndrome, seizure, nerve palsies, and multisystem inflammatory syndrome in children were the most common neurological symptoms caused by COVID-19, whereas encephalitis was commonly seen in patients with Mpox. Rare neurological manifestations of COVID-19 included cerebral venous sinus thrombosis, plexopathies, demyelinating disorders, encephalitis, etc., and rare neurological manifestations of Mpox included headache. CONCLUSIONS: Our review highlights the importance of investigating possible neurological manifestations and closely monitoring these patients to develop a better understanding of the treatment strategies that can be adopted.

[Autoimmune encephalitis and paraneoplastic neurological syndromes presenting atypical parkinsonism: a scoping review].

Recent studies have demonstrated that atypical parkinsonism can be presented in autoimmune encephalitis and paraneoplastic neurological syndromes. However, it is unclear which anti-neural antibodies are involved and when these diseases should be suspected. To address these clinical questions, we conducted a scoping review and analyzed 38 articles. The literature shows that many anti-neural antibodies, including unknown ones, have been reported in progressive supranuclear palsy, corticobasal syndrome, and multiple system atrophy. Moreover, the following symptoms and signs suggest the possibility of autoimmune encephalitis and paraneoplastic neurological syndromes: early onset, acute or subacute progression, the presence of a neoplasm, significant weight loss, abnormal cerebrospinal fluid findings, the absence of typical brain magnetic resonance imaging findings, and the existence of atypical physical examination signs.

Severe encephalitis: aetiology, management and outcomes over 10 years in a paediatric intensive care unit.

OBJECTIVE: To describe the characteristics, differential diagnoses, management and outcomes of severe encephalitis in children. DESIGN: A 10-year retrospective cohort study in children admitted to a tertiary paediatric intensive care unit (PICU) with suspected encephalitis. One to 6 months' follow-up data were compared between different categories. PARTICIPANTS: Patients from 0 to 17 years of age with acute encephalopathy and one or more of fever, seizure, focal neurological findings, cerebrospinal fluid abnormalities, EEG/neuroimaging consistent with encephalitis. MAIN OUTCOME MEASURES: Epidemiology, clinical features, outcomes and risk factor analysis. RESULTS: 175 children with encephalitis required intensive care unit (ICU) admission over 10 years. The median age was 4.5 months (IQR 1.6-54.8). The leading cause was enterovirus (n=49, 28%), followed by parechovirus, influenza, herpes simplex virus (HSV), human herpesvirus-6 (HHV-6), Streptococcus pneumoniae, acute-disseminated encephalomyelitis and anti-N-methyl-D-aspartate-receptor-associated encephalitis. Immune-mediated encephalitis had higher prevalence in females, older age and longer duration of encephalopathy. Mechanical ventilation was required by 74 children (42%); haemodynamic support by 28 children (16%), 3 received extracorporeal membrane oxygenation (ECMO) support. Eleven patients died (case fatality rate 6.3%): five with HHV-6, two enterovirus, two influenza, one HSV, one human-metapneumovirus. At follow-up, 34 children had mild or moderate disability, and six severe disability. In a multivariable logistic regression model, three factors were associated with severe disability or death: age <2 years old (OR 8.2, CI 1.0 to 67.2), Herpesviridae aetiology (OR 14.5, CI 1.2 to 177.3) and length of intubation (OR 1.005, CI 1.00 to 1.01). CONCLUSIONS: Encephalitis has a varied aetiology and causes death or severe disability in 1 in every 10 children requiring intensive care.

Case report: Anti-IgLON5 disease and anti-LGI1 encephalitis following COVID-19.

Anti-IgLON family member 5 (IgLON5) disease is a rare autoimmune encephalitis, characterized by sleep problems, cognitive decline, gait abnormalities, and bulbar dysfunction. Anti-leucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is characterized by cognitive dysfunction, mental disorders, faciobrachial dystonic seizures (FBDS), and hyponatremia. Various studies report that coronavirus disease 2019 (COVID-19) have an effect on the nervous system and induce a wide range of neurological symptoms. Autoimmune encephalitis is one of the neurological complications in severe acute respiratory syndrome coronavirus 2 infection. Until now, autoimmune encephalitis with both anti-IgLON5 and anti-LGI1 receptor antibodies following COVID-19 is rarely reported. The case report described a 40-year-old man who presented with sleep behavior disorder, daytime sleepiness, paramnesia, cognitive decline, FBDS, and anxiety following COVID-19. Anti-IgLON5 and anti-LGI1 receptor antibodies were positive in serum, and anti-LGI1 receptor antibodies were positive in cerebrospinal fluid. The patient presented with typical symptoms of anti-IgLON5 disease such as sleep behavior disorder, obstructive sleep apnea, and daytime sleepiness. Moreover, he presented with FBDS, which is common in anti-LGI1 encephalitis. Therefore, the patient was diagnosed with anti-IgLON5 disease and anti-LGI1 autoimmune encephalitis. The patient turned better after high-dose steroid and mycophenolate mofetil therapy. The case serves to increase the awareness of rare autoimmune encephalitis after COVID-19.

Seronegative acute encephalitis following COVID-19 vaccines: a case series of an overlooked diagnosis with literature review.

PURPOSE: Autoimmune encephalitis is a neurological emergency of new-onset altered mental status, caused by an exaggerated immune-mediated response that targets the central nervous system. Autoimmune encephalitis has become an emerging differential diagnosis, when a classical infection cannot explain neurological symptoms. Displaying overlapping clinical presentations, ranging from the insidious onset of cognitive deficiency to more severe forms of encephalopathy with refractory seizures, autoimmune encephalitis can be challenging for clinicians. When evidence of malignancy is absent and pathogenic autoantibodies are undetected, with typical clinical and imaging features of autoimmune encephalitis, seronegative autoimmune encephalitis may be considered. Recently, vaccination-related autoimmune encephalitis and acute encephalitis after COVID-19 vaccination have attracted attention. METHODS AND RESULTS: We report a case series consisting of three patients with autoimmune encephalitis occurring shortly after COVID-19 vaccination and a current review of all previous reported autoimmune encephalitis related to COVID-19 vaccines. CONCLUSION: We emphasise on the prompt diagnosis of autoimmune encephalitis induced by Covid-19 vaccines and its timely treatment to improve the clinical outcome of this severe neurological condition. Post-licencing vaccine safety surveillance for potential adverse events is essential for vaccine safety and public confidence.

Paraneoplastic Kelch-like protein 11 antibody-associated cerebellar and limbic encephalitis caused by metastatic "burned-out" seminoma - A scar(r)y phenomenon.

INTRODUCTION: The diagnosis of paraneoplastic neurologic syndromes is challenging when the primary tumor masquerades as scar tissue (i.e. "burned-out"). METHODS: Case report. RESULTS: A 45-year-old male patient presented with progressive cerebellar symptoms and hearing loss. Initial screening for malignancy and extensive testing of paraneoplastic and autoimmune neuronal antibodies gave negative results. Repeated whole-body FDG-PET CT revealed a single paraaortic lymphadenopathy, metastasis of a regressed testicular seminoma. Anti-Kelch-like protein-11 (KLHL11) encephalitis was finally diagnosed. CONCLUSION: Our case highlights the importance of continued efforts to find an often burned-out testicular cancer in patients with a highly unique clinical presentation of KLHL11 encephalitis.