Influenza Associated Encephalopathy

1. Influenza-associated
Encephalopathy/Encephalitis
(IAEE)
Ade Wijaya, MD
November 2017

2. Outline
 Introduction
 Epidemiology
 Pathogenesis
 Diagnosis
 Prevention and treatment
 Prognosis
 Summary

3. Introduction
 Very rare but could be serious
 Complicated and challenging diagnostic process
 PCR from CSF?
Wright PF, Webster RG. Orthomyxoviruses. In: Knipe DM, Howley PM. Field’s virology, 4th ed. Philadelphia: Lippincott Raven, 2001: 1533–79
Meijer, W. J., Linn, F. H., Wensing, A. M., Leavis, H. L., van Riel, D., GeurtsvanKessel, C. H., ... & Murk, J. L. (2016). Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging
diagnosis. JMM Case Reports, 3(6).

4. Epidemiology
 mainly affect children (Gu et al., 2013)
 Incidence: 0.21 per million population per year (Hjalmarsson et al., 2009)
 IAE appears to have increased after the 2009 H1N1 influenza A virus pandemic,
with an estimated 12 per million of symptomatic 2009 H1N1 cases (Glaser et al.,
2012; Gu et al., 2013)
 Influenza virus has been identified as the (possible) pathogen in 5–9 % of cases
(Glaser et al., 2006; Koskiniemi et al., 2001; Rantalaiho et al., 2001).

5. Pathogenesis
 Inflammation & infection
 Elevated concentrations of cytokines and anti-influenza antibodies in CSF
 The presence of avian influenza virus receptors and human influenza virus
receptors on neurons, astrocytes and epithelial cells in the brain
Meijer, W. J., Linn, F. H., Wensing, A. M., Leavis, H. L., van Riel, D., GeurtsvanKessel, C. H., ... & Murk, J. L. (2016). Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging
diagnosis. JMM Case Reports, 3(6).

6. Meijer, W. J., Linn, F. H., Wensing, A. M., Leavis, H. L., van Riel, D., GeurtsvanKessel, C. H., ... & Murk, J. L. (2016). Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging
diagnosis. JMM Case Reports, 3(6).

7. Prevention and Treatment
 Influenza vaccination in healthy adults has an efficacy of 59–83 % in preventing
influenza infection (Osterholm et al., 2012).
 Antiviral agents
 Immunomodulatory therapy (corticosteroids)
Meijer, W. J., Linn, F. H., Wensing, A. M., Leavis, H. L., van Riel, D., GeurtsvanKessel, C. H., ... & Murk, J. L. (2016). Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging
diagnosis. JMM Case Reports, 3(6).

8. Prognosis
 Full recovery in 61 %
 Recovery in patients with brain abnormality: 24 %
 Recovery in patients without brain abnormality: 60 %
Meijer, W. J., Linn, F. H., Wensing, A. M., Leavis, H. L., van Riel, D., GeurtsvanKessel, C. H., ... & Murk, J. L. (2016). Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging
diagnosis. JMM Case Reports, 3(6).

9. Summary
 Rare but serious
 In immunocompetent patients
 Inflammatory and infection
 PCR in CSF
 Prevention by vaccine
 Treatment: Antiviral agents and immunomodulatory therapy (corticosteroid)
 Prognosis depend on imaging lesions