1. Department of Neurosurgery, Kantonsspital Aarau, 5001 Aarau, Switzerland
2. Faculty of Medicine, University of Bern, 3012 Bern, Switzerland
3. Department of Neurosciences, University of Calgary, Calgary, AB T2N 1N4, Canada
4. Faculty of Medicine, University of Zürich, 8006 Zürich, Switzerland
5. Department of Neuroradiology, Kantonsspital Aarau, 5001 Aarau, Switzerland
6. Department of Neurosurgery, RWTH Aachen University, 52062 Aachen, Germany