1. Department of Neurosurgery, Acibadem City Clinic University Hospital Tokuda, Sofia, Bulgaria;
2. Institute for Anatomy I, Medical Faculty & University Hospital, Heinrich Heine University Düsseldorf, Düsseldorf, Germany;
3. Department of Diagnostic and Interventional Radiology, Medical Faculty and University Hospital, Heinrich Heine University Düsseldorf, Düsseldorf, Germany;
4. Department of Neurosurgery, Medical Faculty & University Hospital, Heinrich Heine University Düsseldorf, Düsseldorf, Germany