Acute hemorrhagic leukoencephalitis (AHLE)
General description
Acute hemorrhagic leukoencephalitis (AHLE) is recognized as the most severe subtype of Acute disseminated encephalomyelitis (ADEM).
The typical clinical manifestations include encephalopathy, focal neurological symptoms, seizures, and coma, with the acute onset of neurological symptoms occurring within a few weeks after a nonspecific viral infection or vaccination. While ADEM is more commonly reported in children, AHLE is more frequently observed in adults.
Leukocytosis in the peripheral blood can serve as a distinguishing feature between AHLE and ADEM. In AHLE, acute progressive leukoencephalopathy is complicated by hemorrhage and is pathologically characterized by perivascular inflammatory cell infiltration, small vessel necrosis, and demyelination.
Currently, there are no established diagnostic criteria for AHLE, but this condition should be considered in cases of acute progressive encephalitis of unknown cause.
Cerebral lesion
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CerebrumCerebral cortex
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CerebrumCerebral white matter
T2WI/FLAIR typically shows asymmetric hyperintense signals in the white matter, with abnormal signals extending subcortically to areas near the lateral ventricles. In some cases, contrast enhancement and diffusion restriction are observed at the periphery of the lesions. Cerebral swelling is more pronounced than in ADEM, but basal ganglia involvement, which is common in ADEM, is less frequent. Additionally, T2*WI and SWI reveal multiple microhemorrhages within the brain parenchyma.