Acute necrotizing encephalopathy of childhood

Acute necrotizing encephalopathy of childhood (ANEC), also known as acute necrotizing encephalopathy (ANE), is a rare and severe neurological condition characterized by rapid brain damage following a febrile illness, most commonly a viral infection such as influenza or other respiratory viruses. The disease primarily affects the central nervous system, with symmetric, multifocal brain lesions typically involving the bilateral thalami, and often extending to the brainstem tegmentum, cerebral periventricular white matter, putamina, and cerebellar medulla. These lesions represent areas of necrosis (tissue death) and edema, which can be identified on brain MRI. ANEC predominantly affects previously healthy infants and young children, though cases in older children and adults have been reported. Clinical features include rapid onset of seizures, altered consciousness progressing to coma, and neurological deterioration occurring within hours to days of a febrile illness. Liver dysfunction with elevated transaminases may also be present, though unlike Reye syndrome, there is no hyperammonemia or fatty liver infiltration. The disease can be devastating, with high mortality rates and significant neurological sequelae in survivors, including intellectual disability, motor deficits, and epilepsy. A familial or recurrent form, known as acute necrotizing encephalopathy 1 (ANE1), has been linked to heterozygous mutations in the RANBP2 gene (also known as NUP358) on chromosome 2q13, inherited in an autosomal dominant pattern with incomplete penetrance. However, many cases of ANEC are sporadic with no identifiable genetic cause and are thought to result from a dysregulated immune response (cytokine storm) triggered by infection. Treatment is primarily supportive, including intensive care management, seizure control, and measures to reduce intracranial pressure. Immunomodulatory therapies such as high-dose corticosteroids, intravenous immunoglobulin (IVIG), and plasmapheresis have been used, though evidence for their efficacy remains limited. Early recognition and aggressive supportive care may improve outcomes, but no specific curative treatment currently exists.

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