1. Department of Neurology, University of Regensburg, 93053 Regensburg, Germany
2. Department of Anaesthesiology, HELIOS Klinikum, 99089 Erfurt, Germany
3. Department of Neurology, HELIOS Klinikum, 99089 Erfurt, Germany
4. Department of Surgery, University Clinic Regensburg, 93053 Regensburg, Germany