Autoimmune encephalitis in children and adolescents

Innovation and optimization in autoimmune encephalitis trials: the design and rationale for the Phase 3, randomized study of satralizumab in patients with NMDAR-IgG-antibody-positive or LGI1-IgG-antibody-positive autoimmune encephalitis (CIELO)

Background

Autoimmune encephalitis (AIE) encompasses a spectrum of rare autoimmune-mediated neurological disorders, which are characterized by brain inflammation and dysfunction. Autoantibodies targeting the N-methyl-d-aspartic acid receptor (NMDAR) and leucine-rich glioma-inactivated 1 (LGI1) are the most common subtypes of antibody-positive AIE. Currently, there are no approved therapies for AIE. Interleukin-6 (IL-6) signaling plays a role in the pathophysiology of AIE. Satralizumab, a humanized, monoclonal recycling antibody that specifically targets the IL-6 receptor and inhibits IL-6 signaling, has demonstrated efficacy and safety in another autoantibody-mediated neuroinflammatory disease, aquaporin-4 immunoglobulin G antibody-positive neuromyelitis optica spectrum disorder, and has the potential to be an evidence-based disease modifying treatment in AIE.

Objectives

CIELO will evaluate the efficacy, safety, pharmacodynamics, and pharmacokinetics of satralizumab compared with placebo in patients with NMDAR-immunoglobulin G antibody-positive (IgG+) or LGI1-IgG+ AIE.

Study design

CIELO (NCT05503264) is a prospective, Phase 3, randomized, double-blind, multicenter, basket study that will enroll approximately 152 participants with NMDAR-IgG+ or LGI1-IgG+ AIE. Prior to enrollment, participants will have received acute first-line therapy. Part 1 of the study will consist of a 52-week primary treatment period, where participants will receive subcutaneous placebo or satralizumab at Weeks 0, 2, 4, and every 4 weeks thereafter. Participants may continue to receive background immunosuppressive therapy, symptomatic treatment, and rescue therapy throughout the study. Following Part 1, participants can enter an optional extension period (Part 2) to continue the randomized, double-blind study drug, start open-label satralizumab, or stop study treatment and continue with follow-up assessments.

Endpoints

The primary efficacy endpoint is the proportion of participants with a ≥1-point improvement in the modified Rankin Scale (mRS) score from study baseline and no use of rescue therapy at Week 24. Secondary efficacy assessments include mRS, Clinical Assessment Scale of Autoimmune Encephalitis (CASE), time to rescue therapy, sustained seizure cessation and no rescue therapy, Montreal Cognitive Assessment, and Rey Auditory Verbal Learning Test (RAVLT) measures. Safety, pharmacokinetics, pharmacodynamics, exploratory efficacy, and biomarker endpoints will be captured.

Conclusion

The innovative basket study design of CIELO offers the opportunity to yield prospective, robust evidence, which may contribute to the development of evidence-based treatment recommendations for satralizumab in AIE.

A systematic review of the epidemiology of pediatric autoimmune encephalitis: disease burden and clinical decision-making

Background

Autoimmune encephalitis (AIE) comprises a group of rare, immune system-mediated conditions. Clinical manifestations among children are not well-characterized, and there are challenges in testing and diagnosis. This can result in treatment delays, which has been found to correlate with poorer long-term outcomes. This challenge is exacerbated by the scarcity of epidemiological reporting of AIE. The objective of this systematic literature review (SLR) was to identify studies reporting epidemiological data on AIE in children.

Methods

MEDLINE, Embase, the Cochrane Library, and the University of York Centre for Reviews and Dissemination (CRD) were searched in May 2023 for studies reporting on the epidemiology of AIE in children. These were supplemented with additional searches of conference proceedings, gray literature, and the reference lists of identified SLRs. Quality of studies was assessed using a modified version of the Joanna Briggs Institute (JBI) Checklist for Prevalence Studies.

Results

Forty-three publications reporting on 41 unique studies were included. Nine studies reported incidence estimates of different subtypes of AIE, with only one reporting the incidence of overall AIE in children ≤ 18 years, estimated at 1.54 per million children per year in the Netherlands. Three studies reported the incidence of pediatric N-methyl-D-aspartate receptor (NMDAR)-AIE [in United Kingdom (UK), Hong Kong, and Denmark]. The other studies reported incidence data for selected populations.

Conclusion

This SLR highlights a paucity of epidemiology data for AIE in children, which is likely reflective of difficulties in testing and diagnosis. There is a clear need for further research and awareness of these challenges in clinical practice to avoid treatment delays and improve patient outcomes. A deeper understanding of the epidemiology of AIE will help determine the worldwide burden of disease and inform research, health policies and clinical decision-making.

Idiopathic autoimmune encephalitis with a recurrent course. A case report

We presented a clinical case of idiopathic autoimmune brainstem encephalitis in a 12-year-old female patient. At the onset of the disease, which developed after a respiratory infection, the clinical picture was accompanied by oculomotor and bulbar syndromes. The diagnosis of Bickerstaff brainstem encephalitis was made based on clinical diagnostic criteria and the positive effect of the course of intravenous immunoglobulin therapy. During 3 years of follow-up, there were periods of relapse of the disease, during which symptoms not typical for Bickerstaff stem encephalitis appeared. Against the background of long-term immunosuppressive therapy, there was a long-term remission of about 2 years. The clinical picture, the presence of relapses, the data of additional methods forced to reconsider the diagnosis in favor of idiopathic autoimmune brainstem encephalitis.

The Diagnostic Challenge and Prognosis of Autoimmune Encephalitis in Children: A Single-Center Retrospective Study

BACKGROUND

Autoimmune encephalitis (AE) is an immune-mediated encephalitis; nevertheless, its diagnosis in children remains challenging. This study aimed to reveal the clinical characteristics, diagnostic processes, and therapeutic outcomes of AE in children.

METHODS

A total of 18 children with AE were enrolled. Antibody assay was performed in the cerebrospinal fluid (CSF) and serum samples by indirect immunofluorescence. Electroencephalography (EEG) and magnetic resonance imaging (MRI) were monitored to reflect abnormal neural signals. In addition, demographics data, neurological symptoms, therapeutic strategies, and outcomes were recorded and analyzed.

RESULTS

Convulsion (50.00%) and emotional disturbance (44.44%) were common clinical symptoms of AE. The biochemical parameters in the CSF had a relatively low diagnostic value. Antibodies in the CSF were dominant in the diagnosis of AE but those in the serum were limited in the diagnosis of anti-MOG or anti-LGI1 AE. In addition, all children showed abnormalities in EEG (72.22%) or MRI (66.67%). Methylprednisolone combined with sequential oral prednisone (83.33%) and gamma globulin (88.89%) were the dominant drugs, achieving an overall recovery rate of 72.22%. However, there were still two patients who had poor outcomes, including Patient 3 with a young age (two years old) and progressive symptom and Patient 12 with a long disease course before treatment (>120 days).

CONCLUSIONS

The clinical manifestations of AE are varied in children. Antibody in the CSF was dominant, and EEG and MRI were instructive in the diagnosis of AE. Young age, progressive symptom, and prolonged disease course before treatment may contribute to poor outcomes.

EBV-ENCEPHALITIS IN CHILDREN: DIAGNOSTIC CRITERIA

OBJECTIVE

The aim: To investigate the clinical characteristics of EBV infection in the pediatric nervous system using laboratory methods and brain MRI data.

PATIENTS AND METHODS

Materials and methods: We observed 41 children with EBV encephalitis ranging from 8 months to 17 years old. The diagnosis of EBV-encephalitis was established on the basis of clinical and medical history, laboratory and instrumental (brain MRI) data. The main thing in the diagnosis was clinical symptoms, combining general infection, cerebral syndromes and focal neurological symptoms. The etiology of Epstein-Barr virus was determined using ELISA and PCR.

RESULTS

Results: EBV-encephalitis can be as a manifestation of reactivation of persistent EBV infection (85%), much less often - acute primary EBV infection (15%). By nature, the duration of EBV encephalitis has distinguished two forms of its course: acute (63%) and chronioc (37%). The criteria of differential diagnosis of acute and chronic forms of EBV-encephalitis are proposed, which include the most common anamnesis data, clinical manifestations and changes in brain MRI.

CONCLUSION

Conclusions: The proposed criteria specifically for acute and chronic forms of EBV-encephalitis can contribute to the timely and more accurate diagnosis of this disease in children.

LGI-1 encephalopathy following ChAdOx1 nCov-19 vaccination

A 71-year-old male patient was diagnosed with LGI1 encephalopathy 4 weeks following a first ChAdOx1 nCov-19 vaccination. Extensive work-up including analysis of CSF and PET examination did not reveal a tangible cause so that a vaccine-associated encephalopathy was considered as differential diagnosis. Under steroid treatment, the faciobrachial dystonic seizures subsided.

Common immunopathogenesis of central nervous system diseases: the protein-homeostasis-system hypothesis

There are hundreds of central nervous system (CNS) diseases, but there are few diseases for which the etiology or pathogenesis is understood as well as those of other organ-specific diseases. Cells in the CNS are selectively protected from external and internal insults by the blood–brain barrier. Thus, the neuroimmune system, including microglia and immune proteins, might control external or internal insults that the adaptive immune system cannot control or mitigate. The pathologic findings differ by disease and show a state of inflammation that reflects the relationship between etiological or inflammation-inducing substances and corresponding immune reactions. Current immunological concepts about infectious diseases and infection-associated immune-mediated diseases, including those in the CNS, can only partly explain the pathophysiology of disease because they are based on the idea that host cell injury is caused by pathogens. Because every disease involves etiological or triggering substances for disease-onset, the protein-homeostasis-system (PHS) hypothesis proposes that the immune systems in the host control those substances according to the size and biochemical properties of the substances. In this article, I propose a common immunopathogenesis of CNS diseases, including prion diseases, Alzheimer’s disease, and genetic diseases, through the PHS hypothesis.

Epstein-Barr virus meningoencephalitis in a young immunocompetent child: A case report

Epstein-Barr virus (EBV) usually causes mild, asymptomatic, and self-recovered infections in young children. Yet, neurological involvement of this virus has been reported. EBV meningoencephalitis is relatively rare in immunocompetent children. Herein, we describe a case of 2-year-old previously healthy girl presented with high-grade fever and exudative tonsillitis. Her neurological examination showed alteration of consciousness and neck stiffness. A history of generalized tonic-clonic seizures was noted. A diagnosis of EBV meningoencephalitis was definitely confirmed by a positive result for serum viral capsid antigen IgM, and a detection of EBV DNA in cerebrospinal fluid. Her neuroimaging studies demonstrated evidence of leptomeningeal enhancements along bilateral parietal cortical sulci and around the brainstem with a hypodense lesion in the left parietal area - the typical findings of EBV meningoencephalitis. This patient was treated with intravenous corticosteroid without antiviral agents. Her clinical symptoms gradually improved. She was discharged from the hospital on the 19th day of hospitalization without neurological sequelae. Although EBV is not a primary causative agent of meningoencephalitis in immunocompetent children, it should always be considered regardless of the presence or absence of classical infectious mononucleosis symptoms. Early recognition and properly treatment are important for a good prognosis.

Clinical Features and Treatment Outcomes of Seronegative Pediatric Autoimmune Encephalitis

BACKGROUND AND PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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