Received: 8 August 2017
Accepted: 18 December 2017
First Online: 31 January 2018
Ethics approval and consent to participate
: The Clinical Ethics Committee of Saiseikai Yokohamashi Tobu Hospital approved this study. Informed consent was not obtained because this was a retrospective study and person’s information was not included.
: Written informed consent for publication was obtained from the parents of the patients.
: The authors declare that they have no competing interests.
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