1. Department of Trauma and Orthopedic Surgery, University of Witten Herdecke, Cologne Merheim Medical Center, Cologne, Germany.
2. Clinic of Neurosurgery, Faculty of Medicine, University of Cologne, Cologne, Germany.
3. Institute for Research in Operative Medicine, Faculty of Medicine, University of Witten-Herdecke, Cologne, Germany.
4. Institute of Developmental Genetics, National Research Centre for Environment and Health, Munich, Germany.
5. Department of Neurophysiology, Faculty of Medicine, University of Cologne, Cologne, Germany.