1. Department of Neurosurgery, Kantonsspital Sankt Gallen, Sankt Gallen, Switzerland
2. Department of Neurosurgery, Inselspital, University Hospital of Berne, Berne, Switzerland
3. Department of Neurology, Kantonsspital Sankt Gallen, Sankt Gallen, Switzerland
4. Department of Neurosurgery, Freiburg University Medical Center, Freiburg, Germany
5. Department of Neurosurgery, Kantonsspital Aarau AG, Aarau, Switzerland