1. Faculty of Health, Department of Medicine, Witten/Herdecke University, Campus Köln-Merheim, Köln, Institute for Research in Operative Medicine, Köln, Germany;
2. Medical Faculty, Department of Neurosurgery, Recep Tayyip Erdogan University, Rize, Turkey;
3. School of Health, Department of Medical Nursing, Recep Tayyip Erdoğan University, Rize, Turkey;
4. Faculty of Health, Department of Medicine, Witten/Herdecke University, Köln, Germany