1. Department of Neurosurgery, International Neuroscience Institute, Hannover, Germany
2. Department of Neurosurgery, International Neuroscience Institute, Hannover, Germany, and Department of Neurosurgery, University Hospital, Tübingen, Germany
3. Department of Neurosurgery, University Hospital, Freiburg, Germany
4. Department of Neurosurgery, University Hospital, Tübingen, Germany