1. Department of Neurosurgery, Recep Tayyip Erdogan University, Medical Faculty, Riz, Turkey
2. Medical School Brandenburg Theodor Fontane - Campus Neuruppin, Neuruppin, Germany
3. Universität Witten-Herdecke/Campus Köln Merheim - Institut für Forschung in der Operativen Medizin (IFOM), Cologne, Nordrhein-Westfalen, Germany