1. Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
2. Department of Neurosurgery, Medical University Innsbruck, Innsbruck, Austria
3. Department of Neurosurgery, Klinikum Bogenhausen, Munich, Germany
4. Department of Neurosurgery, University Medicine Erfurt, Erfurt, Germany
5. Department of Neurosurgery, Lindenhofspital Bern, Switzerland
6. Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Switzerland