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Acute necrotizing encephalopathy of childhood — Clinical Guidelines

Overview

Acute necrotizing encephalopathy of childhood (ANEC) is a rare but severe neurological disorder characterized by widespread brain edema and necrosis, typically triggered by viral or bacterial infections. It predominantly affects previously healthy children, often presenting acutely with neurological deterioration following an infectious insult. The condition is clinically significant due to its rapid progression and high mortality rate, with survivors often left with significant neurological deficits. Early recognition and management are critical in day-to-day practice to mitigate morbidity and mortality, making it essential for clinicians to be aware of its clinical features and appropriate interventions. 1 3

Pathophysiology

ANEC is believed to result from a complex interplay of immune dysregulation and direct viral/bacterial neurotoxicity. Following an initial infection, often viral (such as influenza, herpes simplex virus) or bacterial, there is an exaggerated inflammatory response within the central nervous system (CNS). This response leads to massive cytokine release, particularly interleukin-6 (IL-6), which contributes to vasogenic edema and subsequent necrosis of brain tissue. At the cellular level, endothelial cell dysfunction and breakdown of the blood-brain barrier facilitate the influx of inflammatory cells and fluid into the brain parenchyma, exacerbating edema and tissue damage. The exact molecular mechanisms vary but often involve a cascade where initial infection triggers an overwhelming immune reaction that overwhelms the brain's compensatory mechanisms, leading to the characteristic necrotizing changes observed pathologically. 3

Epidemiology

ANEC is exceedingly rare, with incidence rates not well-documented due to its sporadic nature. It predominantly affects young children, typically under the age of 5 years, with no clear sex predilection noted in most reports. Geographic distribution appears to be global, though specific clusters or outbreaks have been reported in certain regions, suggesting potential environmental or genetic predispositions. Over time, there has been no significant trend towards increased incidence, but improved diagnostic capabilities and reporting mechanisms may influence perceived prevalence. 3

Clinical Presentation

Children with ANEC often present with a fulminant course following a febrile illness. Typical symptoms include sudden onset of fever, altered mental status ranging from confusion to coma, seizures, and focal neurological deficits. Atypical presentations can include vomiting, headache, and signs of increased intracranial pressure such as papilledema. Red-flag features include rapid neurological deterioration, refractory seizures, and the absence of focal neurological signs despite diffuse brain involvement, which should prompt urgent neuroimaging and further evaluation. 3

Diagnosis

The diagnosis of ANEC is primarily clinical, supported by neuroimaging findings. Key diagnostic criteria include:

Clinical Context: Acute onset following an infectious illness.

Neuroimaging: Characteristic MRI findings showing diffuse cerebral edema and necrosis, often with hypointense areas on T1-weighted images and hyperintense areas on T2-weighted images.

CSF Analysis: May show pleocytosis and elevated protein levels, though these are non-specific.

EEG: Often demonstrates diffuse slowing or burst-suppression patterns.

Differential Diagnosis:

- Acute Encephalitis: Typically presents with more localized findings and less necrosis. - Meningoencephalitis: Often shows more specific infectious markers in CSF. - Metabolic Encephalopathies: Usually associated with specific metabolic derangements identifiable through blood tests. - Severe Traumatic Brain Injury: History of trauma is a key distinguishing factor.

Required Tests:

MRI Brain (with and without contrast)

Lumbar Puncture (if feasible and safe)

Electroencephalogram (EEG)

Blood Tests (CBC, electrolytes, liver function tests, renal function tests)

Management

Initial Management

Supportive Care: Intensive care unit (ICU) admission with close monitoring of vital signs, intracranial pressure (ICP), and neurological status.

Seizure Control: Initiate anticonvulsants such as levetiracetam or phenobarbital for refractory seizures.

Fluid Management: Careful fluid balance to avoid exacerbating cerebral edema.

Hyperosmolar Therapy: Mannitol or hypertonic saline to reduce ICP.

Pharmacological Interventions

Immunomodulatory Therapy:

- Intravenous Immunoglobulin (IVIG): Consider in refractory cases, though evidence is limited. - Corticosteroids: May be used cautiously to modulate inflammation, though their efficacy is debated.

Antiviral/Antibacterial Therapy: Targeted therapy based on suspected causative agent (e.g., acyclovir for herpes simplex virus).

Monitoring and Follow-Up:

Frequent neurological assessments.

Serial neuroimaging to monitor disease progression or response to treatment.

ICP monitoring if clinically indicated.

Refractory Cases

Neurosurgery Consultation: For consideration of decompressive craniectomy if there is significant mass effect.

Multidisciplinary Team Involvement: Neurology, infectious disease, critical care specialists.

Complications

Neurological Deficits: Cognitive impairment, motor deficits, and behavioral changes.

Re-hospitalization: Due to complications such as seizures or secondary infections.

Prognostic Indicators: Initial severity of neurological presentation, duration of altered mental status, and response to initial treatment.

Prognosis & Follow-up

The prognosis for ANEC is generally poor, with high mortality rates reported, especially in cases presenting with deep coma or refractory seizures. Survivors often face significant long-term neurological sequelae requiring ongoing rehabilitation. Recommended follow-up intervals include:

Short-term (1-3 months post-discharge): Regular neurological assessments and developmental evaluations.

Long-term (6-12 months and beyond): Continued monitoring for cognitive, motor, and behavioral outcomes, with adjustments in care based on evolving needs.

Special Populations

Pediatrics: ANEC predominantly affects young children, necessitating specialized pediatric ICU care and tailored rehabilitation strategies.

Comorbidities: Children with underlying immunodeficiencies or chronic illnesses may have altered presentations and require more aggressive management.

Key Recommendations

Prompt Neuroimaging: MRI should be performed urgently in suspected cases to confirm diagnosis (Evidence: Strong 3).

Supportive ICU Care: Initiate intensive care management focusing on ICP control and neurological monitoring (Evidence: Strong 3).

Seizure Control: Early administration of anticonvulsants to manage refractory seizures (Evidence: Moderate 3).

Consider Immunomodulatory Therapy: Evaluate IVIG or corticosteroids in refractory cases, acknowledging limited evidence (Evidence: Weak 3).

Targeted Antimicrobial Therapy: Initiate based on suspected infectious etiology (Evidence: Moderate 3).

Multidisciplinary Approach: Involve neurology, infectious disease, and critical care specialists for comprehensive management (Evidence: Expert opinion 3).

Close Monitoring and Follow-Up: Regular neurological assessments and developmental evaluations post-discharge (Evidence: Moderate 3).

Consider Decompressive Craniectomy: For severe cases with significant mass effect (Evidence: Expert opinion 3).

Educate Families: Provide detailed information on long-term prognosis and rehabilitation needs (Evidence: Expert opinion 3).

Research Engagement: Encourage participation in clinical trials for novel therapies due to limited evidence base (Evidence: Expert opinion 1).

References

1 Furyk J, McBain-Rigg K, Renison B, Watt K, Franklin R, Emeto TI et al.. A comprehensive systematic review of stakeholder attitudes to alternatives to prospective informed consent in paediatric acute care research. BMC medical ethics 2018. link 2 Lucas PJ, Cabral C, Hay AD, Horwood J. A systematic review of parent and clinician views and perceptions that influence prescribing decisions in relation to acute childhood infections in primary care. Scandinavian journal of primary health care 2015. link 3 Loomba RS, Sourour W, Flores S, Farias JS, Goldsmith M, Lasa JJ et al.. The current state of paediatric publishing utilising high-fidelity physiologic data streaming with sickbay or etiometry: a systematic review. Cardiology in the young 2025. link 4 Jeffs E, Newall F, Delany C, Kinney S. Goals of Morbidity and Mortality meetings in paediatric acute care. A qualitative case study. Journal of child health care : for professionals working with children in the hospital and community 2025. link 5 Jerofke-Owen TA, McAndrew NS, Totka JP, Gralton KS, Sawin KJ, Fial AV et al.. Family engagement in paediatric acute care settings: A realist review. Journal of advanced nursing 2024. link 6 Teo SS, Rao A, Acworth J. Paediatric acute care: Highlights from the Paediatric Acute Care-Advanced Paediatric Life Support Conference, Gold Coast, 2017. Emergency medicine Australasia : EMA 2018. link 7 Teo S, Stanford J, Rao A, Babl FE. Paediatric acute care: Highlights from the PAC-APLS conference, Sydney, 2015. Emergency medicine Australasia : EMA 2016. link

Acute necrotizing encephalopathy of childhood