Received: 3 June 2017
Accepted: 16 February 2018
First Online: 27 February 2018
Ethics approval and consent to participate
: Due to the retrospective study design an ethics approval for this case series was not necessary.§ 2 (1) and (2) of the Statutes of the Ethics Committee of the University of Lübeck.
: Not applicable. Our manuscript does not contain any individual personal data.
: The authors declare that they have no competing interests.
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