Funding for this research was provided by:
FP7 Research Potential of Convergence Regions (EuroHeadPain (#602633))
Deutsche Forschungsgemeinschaft (SFB936/A5)
Text and Data Mining valid from 2018-03-20
Received: 31 January 2018
Accepted: 28 February 2018
First Online: 20 March 2018
Ethics approval and consent to participate
: The study was approved by the local ethics committee of the Ärztekammer Hamburg, PV5011 and all participants gave written informed consent.
: All authors have seen and agreed to the content. All authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.