1. Department of Neurosurgery, University of Düsseldorf;
2. Department of Neurosurgery, University of Hamburg-Eppendorf, Germany
3. Institute of Neuroscience and Medicine, Research Center Jülich;
4. Department of Neurology, University of Cologne;
5. Department of Spine and Pain, St.-Vinzenz-Hospital, Düsseldorf; and