1. Department of Neurosurgery, Johannes Wesling Klinikum, University Hospital of Ruhruniversität Bochum, Minden
2. Department of Neurosurgery, Vivantes Klinikum Friedrichshain, Berlin
3. Department of Neurosurgery, Helios Kliniken, Erfurt
4. Department of Neurosurgery, Johannes Gutenberg Universität, Mainz
5. Department of Neurosurgery, Universitätskrankenhaus Eppendorf, Hamburg
6. Department of Neurosurgery, Universitätsklinikum Tübingen, Germany