1. Department of Neurosurgery, University Medical Center Freiburg, Freiburg/Breisgau, Germany
2. Department of Neurosurgery, University Hospital Essen, Essen, Germany
3. Department of Neurology, University Medical Center Freiburg, Freiburg/Breisgau, Germany
4. Institute for Medical Biometry and Medical Informatics, University Medical Center Freiburg, Freiburg/Breisgau, Germany
5. Department of Neuroradiology, University Medical Center Freiburg, Freiburg/Breisgau, Germany