The Clinical and Imaging Characteristics Associated With Neurological Sequelae of Pediatric Patients With Acute Necrotizing Encephalopathy

The Spectrum of Influenza-Associated Acute Necrotizing Encephalopathy of Childhood: A Case Series

BACKGROUND

Acute necrotizing encephalopathy of childhood (ANEC) is a rare inflammatory neurological disease with characteristic neuroimaging findings commonly leading to disability or death. It is associated with a variety of infectious agents, most commonly influenza.

METHODS

This study is a retrospective case series describing three children presenting with ANEC during the 2023-2024 influenza season.

RESULTS

All patients were influenza A positive with a variable duration of prodromal infectious symptoms. Each presented with witnessed or suspected seizures and persistent encephalopathy. Initial computed tomography (CT) was unremarkable in two patients; however, on follow-up neuroimaging all evolved multifocal brain lesions, including symmetric bilateral thalamic involvement consistent with ANEC. All patients received intravenous pulse methylprednisolone, but the timing and selection of additional immunomodulatory interventions differed between patients. Outcomes spanned from slight disability to death.

CONCLUSIONS

These patients illustrate the spectrum of ANEC presentations and outcomes and underscore the importance of prompt investigations in children with persistent encephalopathy and prodromal infectious symptoms, even with unremarkable findings on initial CT. The variability in treatment and outcomes within a single center emphasizes the need for further research to establish a better pathophysiologic understanding of ANEC and optimal treatment protocols.

Characteristics and outcome of influenza-associated encephalopathy/encephalitis among children in China

BACKGROUND

Influenza-Associated Encephalopathy/Encephalitis (IAE) is characterized by high incidence and poor prognosis. The aim of this study is to describe the clinical features and outcomes of IAE in pediatric patients.

METHODS

We performed a retrospective review of hospitalized cases of laboratory-confirmed influenza infection between January 2018 and December 2021. Demographic, clinical, imaging, treatment and outcome data were collected. Statistical analysis was performed using SPSS software.

RESULTS

Of 446 children hospitalized with influenza, 71 cases were identified with a diagnosis of IAE. The median age was 3 years and 46 (64.8 %) were younger than 5 years. Only one patient was vaccinated for seasonal influenza. 46 (64.8 %) patients had abnormal electroencephalogram examination and 47 (66.2 %) had abnormal brain MRI or CT findings. 68 (95.8 %) patients were treated with oseltamivir/peramivir. 12 (16.9 %) patients suffered mortality. Non-survivors were more likely to have lower Glasgow coma score (median 7), longer duration of fever (median 3 days), with underlying medical conditions (P = 0.006), and complications including sepsis (P = 0.003), shock (P < 0.001), respiratory failure (P = 0.006), acute renal failure (P = 0.001), myocardial damage (P < 0.001), coagulation disorders (P = 0.03), electrolyte disturbance (P = 0.001) and hyperlactacidemia (P = 0.003). Non-survivors had higher percentages of corticosteroids (P = 0.003) and immunoglobulin (P = 0.003) treatments compared to survivors.

CONCLUSIONS

Children with IAE have a high mortality rate. Lower Glasgow coma score, longer duration of fever, with underlying medical conditions and complications pose a great risk to poor prognosis. Influenza vaccination is recommended to all eligible children.

Case report: Acute necrotizing encephalopathy: a report of a favorable outcome and systematic meta-analysis of outcomes with different immunosuppressive therapies

Acute Necrotizing Encephalopathy (ANE) is a condition characterized by symmetric, bilateral lesions affecting the thalamus and potentially other areas of the brain following an acute febrile illness. It manifests clinically as abrupt development of encephalopathy, or alteration in mental status that often includes development of seizures and progression to coma. Treatment strategies combine immunosuppressive therapies and supportive care with varying levels of recovery, however there are no universally accepted, data-driven, treatment algorithms for ANE. We first report a case of a previously healthy 10-year-old female with acute onset diplopia, visual hallucinations, lethargy, and seizures in the setting of subacute non-specific viral symptoms and found to have bilateral thalamic and brainstem lesions on MRI consistent with ANE. She was treated with a combination of immunomodulatory therapies and ultimately had a good outcome. Next, we present a meta-analysis of 10 articles with a total of 158 patients meeting clinical and radiographic criteria for ANE. Each article reported immunosuppressive treatments received, and associated morbidity or mortality outcome for each individual patient. Through our analysis, we confirm the effectiveness of high-dose, intravenous, methylprednisolone (HD-IV-MP) therapy implemented early in the disease course (initiation within 24 h of neurologic symptom onset). There was no significant difference between patients treated with and without intravenous immunoglobulin (IVIG). There was no benefit of combining IVIG with early HD-IV-MP. There is weak evidence suggesting a benefit of IL-6 inhibitor tocilizumab, especially when used in combination with early HD-IV-MP, though this analysis was limited by sample size. Finally, plasma exchange (PLEX) improved survival. We hope this meta-analysis will be useful for clinicians making treatment decisions for patients with this potentially devastating condition.

Timing of therapeutic interventions against infection-triggered encephalopathy syndrome: a scoping review of the pediatric literature

Our goal was to conduct a scoping review of the literature on the treatment of infection-triggered encephalopathy syndrome/acute encephalopathy in children, focusing on treatment targets and treatment initiation timing. We performed literature searches using PubMed for articles reporting treatments of infection-triggered encephalopathy syndrome/acute encephalopathy. We included articles describing specific treatments for acute encephalopathy with control groups. For the purpose of searching new therapies only experimentally tried in the case series, we also included case series studies without control groups in this review, if the studies contained at least two cases with clear treatment goals. Therapies were classified based on their mechanisms of action into brain protection therapy, immunotherapy, and other therapies. We operationally categorized the timing of treatment initiation as T1 (6-12 h), T2 (12-24 h), T3 (24-48 h), and T4 (>48 h) after the onset of seizures and/or impaired consciousness. Thirty articles were included in this review; no randomized control study was found. Eleven retrospective/historical cohort studies and five case-control studies included control groups with or without specific therapies or outcomes. The targeted conditions and treatment timing varied widely across studies. However, the following three points were suggested to be effective in multiple studies: (1) Careful seizure management and targeted temperature management within 12 h (T1) of onset of febrile seizure/prolonged impaired consciousness without multiple organ failure may reduce the development of acute encephalopathy with biphasic seizures and late reduced diffusion; (2) immunotherapy using corticosteroids, tocilizumab, or plasma exchange within 24 h (T1-T2) of onset of acute necrotizing encephalopathy may reduce sequelae; and (3) anakinra therapy and ketogenic diet demonstrate little evidence of neurologic sequelae reduction, but may reduce seizure frequency and allow for weaning from barbiturates, even when administered weeks (T4) after onset in children with febrile infection-related epilepsy syndrome. Although available studies have no solid evidence in the treatment of infection-triggered encephalopathy syndrome/acute encephalopathy, this scoping review lays the groundwork for future prospective clinical trials.

Treatment of severe acute necrotizing encephalopathy of childhood with interleukin-6 receptor blockade in the first 24 h as add-on immunotherapy shows favorable long-term outcome at 2 years

BACKGROUND

Acute necrotizing encephalopathy (ANE) of childhood is a rare and devastating infection-associated acute encephalopathy. While there are no consensus treatments for ANE, recent case reports suggest a beneficial role for the use of tocilizumab, a recombinant humanized monoclonal antibody against the interleukin-6 (IL-6) receptor. The correlation of the timing of add-on tocilizumab in relation to long-term outcome has not been reported.

METHODS

We report on the timing of administration of tocilizumab in two patients classified as high-risk using the ANE severity score (ANE-SS) with respect to the long-term outcome at 2 years.

RESULTS

Case 1 was a 19-month-old previously well boy who presented to a tertiary children's hospital with seizures, evolving status dystonicus and shock. Case 2 was a three-year-old boy who presented to a peripheral hospital with fever, sepsis and encephalopathy. The patients were transferred to the tertiary intensive care unit and MRI confirmed ANE with extensive brainstem involvement. Case 1 received intravenous immunoglobulin (IVIg), methylprednisolone and tocilizumab at 21, 39 and 53 h respectively. His modified Rankin scale (mRS) at discharge and two years was unchanged at 5. The functional independence measure - for children (WeeFIM) at two years was very low (19/126). Case 2 received dexamethasone at 1 h, methylprednisolone at 21 h and IVIg and tocilizumab at 22 h. The mRS at discharge and two years was 4 and 3 respectively. The WeeFIM score at two years showed substantial improvement (96/126).

CONCLUSION

The very early use of interleukin-6 blockade as 'add-on' immunotherapy in the first 24 h demonstrates potential for improving the long-term outcome in patients classified as high-risk using the ANE-SS.

Pathogenesis and Management of Acute Necrotizing Encephalopathy

INTRODUCTION

During the COVID-19 pandemic, many cases of acute necrotizing encephalopathy (ANE) secondary to COVID-19 have been reported. ANE is characterized by a rapid onset, a fulminant course, and low morbidity and fatality rates. Therefore, clinicians need to be vigilant for such disorders, especially during the influenza virus and COVID-19 epidemics.

AREAS COVERED

The authors summarize the most recent studies on the clinical spectrum and treatment essentials of ANE to provide references for prompt diagnosis and improved treatment of this rare but fatal disease.

EXPERT OPINION

ANE is a type of necrotizing lesion of the brain parenchyma. There are two major types of reported cases. One is isolated and sporadic ANE, which is primarily caused by viral infections, particularly influenza and HHV-6 virus. The other type is familial recurrent ANE, which is caused by RANBP2 gene mutations. ANE patients have rapid progression and a very poor prognosis, with acute brain dysfunction occurring within days of viral infection and requiring admission to the intensive care unit. Clinicians still need to investigate and find solutions for the problems of early detection and treatment of ANE.

Factors associated with outcomes of severe acute necrotizing encephalopathy: A multicentre experience in Malaysia

This case series compared clinical variables and various combinations of immunotherapy received with outcomes of patients with severe acute necrotizing encephalopathy (ANE). We performed a retrospective review of clinical variables, immunotherapy received, and outcomes (based on the modified Rankin Scale) in Malaysia between February 2019 and January 2020. Twenty-seven children (12 male), aged 7 months to 14 years (mean 4 years) at diagnosis were included. Of these, 23 had an ANE severity score of 5 to 9 out of 9 (high risk). Eleven patients received tocilizumab (four in combination with methylprednisolone [MTP], seven with MTP + intravenous immunoglobulin [IVIG]) and 16 did not (two received MTP alone, 14 received MTP + IVIG). Nine died. Among the survivors, six had good outcomes (modified Rankin Score 0-2) at 6 months follow-up. All patients who received tocilizumab in combination with MTP + IVIG survived. Twenty children received first immunotherapy within 48 hours of admission. No significant association was found between the timing of first immunotherapy with outcomes. Those with brainstem dysfunction (p = 0.016) were observed to have poorer outcomes. This study showed a trend towards better survival when those with severe ANE were treated with tocilizumab in combination with MTP + IVIG. However, larger studies will be needed to determine the effect of this regime on the long-term outcomes.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.