1. Department of Neurosurgery University Medical Center Freiburg Freiburg Germany
2. Department of Neurosurgery, Faculty of Medicine of Geneva Geneva University Hospital Geneva Switzerland
3. Department of Neurosurgery, Inselspital, Bern University Hospital University of Bern Bern Switzerland
4. Department of Diagnostic and Interventional Neuroradiology University Medical Center Freiburg Freiburg Germany
5. Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital University of Bern Bern Switzerland