1. Department of Neurosurgery, Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland
2. Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, United States
3. Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle, Germany
4. Department of Neurosurgery, Stroke Center, Sapporo Teishinkai Hospital, Sapporo, Hokkaido, Japan
5. Department of Neurosurgery, BG-Klinikum Bergmannstrost GmbH, Merseburger Straße 165, Halle 06112, Germany
6. Barrow Neurosurgical Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, United States