[Influenza A-associated acute necrotizing encephalopathy].

Introduction: Acute necrotizing encephalopathy of childhood (ANEC) is a rare disease characterized by alteration of consciousness and multiple symmetric brain lesions mainly involving the thalamus. It presents a high mortality rate and severe sequelae.

Objective: To describe a school-age patient with influenza A-related ANEC with favorable evolution.

Clinical case: Six-year-old boy with 3 days history of upper respiratory symptoms and fever (39 °C). One day previous to admission, he presented altered state of consciousness. A lumbar puncture was performed, showing a mild increase of protein level in CSF. MRI showed bilateral foci of symmetric restricted signal in the thalamus, mammillary bodies, periaqueductal gray, ventral tegmentum, hippocampus, and in both external capsules, which was compatible with ANEC. The patient received empirical treatment with methylprednisolone and oseltamivir. Subsequently, a positive result was received for influenza. Considering diagnosis and severity of illness, it was decided to administer immunoglobulin. The patient got better slowly but favorably. At discharge, he still was mildly bradypsychic with decreased visual acuity, spontaneous speech and walking with assistance. At 6 months of follow-up, the patient presented normal speech and gait, with persistent visual impairment in the right eye.

Conclusions: Our patient presented ANEC, whose timely diagnosis and management were associated with a favorable neurological evolution in the long term. Although ANEC is an infrequent pathology, it has very high morbidity and mortality rates, so it is very important to have a high degree of suspicion in order to request a targeted imaging study, search for related infectious causes, and start proper treatment.