Acute necrotizing encephalopathy (ANE)
General description
Acute Necrotizing Encephalopathy (ANE) is a specific type of acute encephalopathy distinguished by bilateral symmetrical lesions in the thalamus, evident on head CT and MRI scans. This condition is often triggered by viral infections that induce high fever, such as influenza, parainfluenza, varicella, enterovirus, COVID-19, and other viruses.
The underlying pathogenesis of ANE is believed to involve an inflammatory cytokine storm, leading to severe brain symptoms like rapid loss of consciousness, signs of intracranial hypertension, and convulsions. Most cases of ANE occur sporadically, but some recurrent or familial cases have been reported, which are associated with mutations in the RANBP2 gene.
ANE can also affect multiple organs beyond the brain, including the liver, kidney, heart, and muscles, indicating a systemic impact. Despite its acute and transient nature, the prognosis for ANE is frequently poor, highlighting the severity of this condition.
White matter and brainstem lesion
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CerebrumCerebral white matter
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CerebellumCerebellar white matter
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Brainstem
Hemorrhagic events can be observed in the tegmentum of the brainstem, cerebellar white matter, and cerebral white matter, in addition to bilateral thalamus.
Early phase
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Thalamus
In the relatively early stage of the disease, MRI reveals bilateral T2WI and FLAIR hyperintensity along with T1WI hypointensity, reflecting edematous changes.
Subacute phase
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Thalamus
In the relatively subacute phase of the disease, MRI shows a characteristic concentric appearance on ADC maps, with peripheral low signal and central high signal. In the central portion of the lesion, hemorrhagic changes cause T1WI hyperintensity and SWI/T2*WI hypointensity.