1. Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland;
2. Department of Neurosurgery, University Hospital Muenster, Münster, Germany;
3. Department of Neurosurgery, Medical Center—University of Freiburg, Freiburg, Germany;
4. Department of Neurosurgery, Lindenhofspital, Bern, Switzerland;
5. Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland