1. Department of Neurosurgery, Johannes Gutenberg-University, Mainz, Germany
2. Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
3. Department of Neurosurgery, Katharinenhospital, Klinikum Stuttgart, Germany
4. Department of Neurosurgery, Clinique Ste Thérése, Luxembourg, Luxembourg
5. Department of Neurosurgery, Städtische Krankenanstalten Idar-Oberstein, Idar-Oberstein, Germany
6. Department of Neurosurgery, University Medical Center Nijmegen, Nijmegen, the Netherlands
7. Department of Neurosurgery, Landesklinikum St Pölten, St Pölten, Austria
8. Department of Neurosurgery, Medical University Vienna, Wien, Austria