A boy aged two years and one month presented with several days of fever, vomiting, irritability, and progressive limb weakness. On arrival, he was drowsy (Glasgow Coma Score [GCS] E3 V3 M5) and hemodynamically stable. The laboratory tests were unremarkable, and a respiratory antigen test was positive for adenovirus. The non-contrast brain computed tomography (CT) showed bilateral symmetrical hypodensities in the basal ganglia (Fig. 1). The patient was admitted to the intensive care unit due to declining level of consciousness. The results of cerebrospinal fluid analysis were unremarkable, with negative bacterial and viral cultures. He received intravenous immunoglobulin, pulse steroids, mannitol, and supportive care. Magnetic resonance imaging (MRI) subsequently revealed symmetric diffusion restriction in the basal ganglia (Fig. 2), consistent with acute necrotizing encephalopathy of childhood. A metabolic workup ruled out inherited metabolic disorders. He was discharged in stable condition with residual emotional lability and impaired speech.

Figure 1.

Axial (A) and coronal (B) non-contrast CT images showing symmetric bilateral basal ganglia hypodensities (arrowheads).

Figure 2.

(A) Axial T2-weighted FLAIR image showing symmetric hyperintensities in the bilateral basal ganglia. (B) Diffusion-weighted imaging demonstrates restricted diffusion. (C) The corresponding apparent diffusion coefficient (ADC) map reveals a central hypointense core with a surrounding hyperintense rim, consistent with acute necrotizing encephalopathy of childhood.

Acute necrotizing encephalopathy of childhood is a fulminant, infection-related encephalopathy with a high mortality and substantial long-term sequelae among survivors.1 Symmetric basal ganglia and thalamic lesions are radiological hallmarks and are best visualized on CT and diffusion-weighted MRI.2 Given the poor prognosis despite therapy, prompt recognition of these characteristic findings in the emergency care setting is essential to enable timely intervention and maximize the probability of a favorable outcome.3