Clinical, neuropsychological and radiological features in influenza virus-associated encephalitis: a case series

BACKGROUND: Influenza virus-associated encephalitis is a rare but potentially threatening complication of influenza. Although it has been reported in various populations, its pathophysiological, clinical, radiological and neuropsychological features remain largely unknown. Further data are therefore needed to develop appropriate management strategies. CASE PRESENTATION: We describe four French patients (two adults and two children) presenting with neurologic impairment after confirmed influenza, leading to the diagnosis of influenza virus-associated encephalitis. All of them were assessed using an extensive framework including EEGs, brain MRIs and cognitive evaluations. Relevant clinical and biological outcomes are reported for each patient. CONCLUSIONS: This case series illustrates the diversity in the initial presentation, trajectories and outcomes of patients diagnosed with influenza virus-associated encephalitis. The reported clinical and paraclinical features point to potentially distinct forms of the disease in terms of pathophysiological mechanisms, with possible prognostic implications. For mild cases, these data suggest that complete recovery may be obtained within a few weeks after the infection, particularly at the neuropsychological level. They also emphasize the importance of early recognition and management of influenza virus-associated encephalitis.