Unenhanced CT of the head demonstrated symmetric low attenuation within the bilateral medial thalami with a normal CT angiogram and CT venogram (Fig 1). Brain MRI demonstrated hemorrhagic rim-enhancing lesions within the bilateral thalami, medial temporal lobes, and subinsular regions (Fig 2). The patient was started on intravenous immunoglobulin. High-dose steroids were not initiated due to concern for respiratory compromise.

Acute necrotizing encephalopathy is a rare complication of influenza and other viral infections and has been related to intracranial cytokine storms, which result in blood-brain barrier breakdown but without direct viral invasion or parainfectious demyelination (3). Accumulating evidence suggests that a subgroup of patients with severe COVID-19 might have cytokine storm syndrome (4). Although predominantly described in the pediatric population, acute necrotizing encephalopathy is known to occur in adults as well. The most characteristic imaging feature includes symmetric, multifocal lesions with invariable thalamic involvement (5). Other commonly involved locations include the brainstem, cerebral white matter, and cerebellum (5). Lesions appear hypoattenuating on CT images, and MRI demonstrates T2-weighted fluid-attenuated inversion recovery hyperintense signal with internal hemorrhage. Contrast material–enhanced images may demonstrate a ring of contrast enhancement (5).