Response to “Brain Magnetic Resonance Imaging in Influenza A (H1N1) 2009-Associated Encephalopathy”

Brain Magnetic Resonance Imaging in Influenza A (H1N1) 2009-Associated Encephalopathy

Thank you for your “Letter to the Editor” regarding our article “Brain MRI in Pandemic Influenza A (H1N1) 2009-Associated Encephalopathy” published in the journal Neuropediatrics. We appreciate your insightful comments.

The present research[1] reexamined previous research on the national survey of pdm 2009-associated encephalopathy.[2] In the previous research, 25% of the cases had abnormalities on MRI “among the cases with good outcomes.” On the contrary, in this study, we focused on “all cases in which MRI was performed in the acute phase of encephalopathy.” The population involved is different and thus the percentage of cases with abnormalities on magnetic resonance imaging (MRI) was different.

In the acute phase of pandemic influenza A (H1N1) 2009-associated encephalopathy, there is also a possibility that abnormalities cannot be detected on brain MRI. Therefore, we agree with you that if continuous follow-up MRI is not performed, the resolution of a brain lesion might not be detectable.

Moreover, the status of consciousness is the most important aspect for the diagnosis of acute encephalopathy. We believe that it should be diagnosed comprehensively in reference to the findings including neurological findings, electroencephalogram, and neuroimaging among others.

• References

• 1 Ishida Y, Kawashima H, Morichi S , et al. Brain magnetic resonance imaging in acute phase of pandemic influenza A (H1N1) 2009-associated encephalopathy in children. Neuropediatrics 2015; 46 (1) 20-25
• 2 Kawashima H, Morichi S, Okumara A, Nakagawa S, Morishima T ; collaborating study group on influenza-associated encephalopathy in Japan. National survey of pandemic influenza A (H1N1) 2009-associated encephalopathy in Japanese children. J Med Virol 2012; 84 (8) 1151-1156