Influenza A-associated acute necrotising encephalopathy in a 10-year-old child

We report an otherwise healthy 10-year-old boy who was brought to the emergency department with altered mental status, vomiting, diarrhoea and fever (39.5°C), without signs of meningitis. The CT scan revealed bilateral hypodensities of the thalamus and cerebellum, with diffuse oedema and slight compression of the brainstem and a triventricular hydrocephalus. Lumbar puncture and blood examination revealed markedly elevated protein level of 2.4 g/L in cerebrospinal fluid and high serum aminotransferase, characteristic of acute necrotising encephalopathy (ANE). The PCR of the nasopharyngeal swab was influenza A positive. Because of signs of high intracranial pressure, mannitol was given, an external ventricular drain was placed and subsequently, a posterior fossa craniectomy was performed. Postoperatively, he showed signs of cerebellar mutism with emotional instability and diminished speech. Six months after presentation, he showed full recovery. This case illustrates ANE as a rare complication of influenza A infection.

Keywords: coma and raised intracranial pressure; infection (neurology); influenza; paediatric intensive care.