Hemispheric AESD: Half-Bright Tree Appearance in a Child With Hepatitis A

Abstract

A previously healthy, 3-year-old girl developed acute-onset high-grade fever, jaundice, and irritability over the past 2 weeks followed by recurrent, generalized tonic–clonic seizures and encephalopathy. Developmental and family history was unremarkable. On examination, she had pallor, icterus, hepatosplenomegaly (liver span 10 cm), encephalopathy, generalized hypotonia, brisk muscle stretch reflexes, bilateral Babinski sign, acral dyskinesia, and normal fundi. Investigations showed anemia (hemoglobin 61 g/L), conjugated hyperbilirubinemia (4.99 mg/dL), transaminitis (aspartate aminotransferases 1237 IU/L, alanine aminotransferases 772 IU/L), coagulopathy, hyperammonemia (141 mmol/L), elevated arterial lactate (2.5 mmol/L), hepatitis A seropositivity, and normal cerebrospinal fluid analysis. Neuroimaging showed hemispheric form of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD; Figure 1A and B). She recovered with supportive care and protein restriction with no recurrence of seizures or encephalopathy. Repeat neuroimaging (Figure 1C and D) showed complete resolution of abnormalities. Acute encephalopathy with biphasic seizures and late reduced diffusion is a recently proposed infectious encephalopathy syndrome characterized by febrile encephalopathy, biphasic seizures, and late subcortical reduced diffusion during day 3 to day 9 of illness. The hallmark diffusion-weighted radiological appearance has been christened as a “bright tree appearance” secondary to the excitotoxic neuronal damage and resultant white matter edema. The lesions are classically divided into a severe “diffuse” or a milder “central-sparing” patterns. Half-bright tree appearance due to “hemispheric involvement” is a distinctive third pattern of involvement in AESD. These children need neurodevelopmental follow-up as unilateral hemispheric presentation may be a precursor to hemiplegia–hemiconvulsion syndrome.