1. 1Department of Neurosurgery, Johann Wolfgang Goethe University, Frankfurt am Main, Germany;
2. 2Department of Neurosurgery, University of Milan, Italy;
3. 3Department of Neurosurgery, University of Montpellier, France;
4. 4Department of Neurosurgery, University of Tübingen, Germany;
5. 5Department of Neurosurgery, University Hospital, Banská Bystrica, Slovakia;
6. 6Department of Neurosurgery, University of Bonn, Germany;
7. 7Department of Neurosurgery, University of Catanzaro; and
8. 8Department of Neurosurgery, University of Verona, Italy