1. Department of Neurosurgery, Cairo University, Cairo, Egypt
2. Department of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences at University at Buffalo, Buffalo, New York, USA
3. Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
4. Department of Neurosurgery Royal Victoria Infirmary, Newcastle-upon-Tyne, United Kingdom