1. Department of Neurosurgery, Faculty of Medicine, Cairo University, Cairo, Egypt;
2. Department of Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt;
3. Department of Neurosurgery, University of Toronto, Toronto, Ontario, Canada;
4. Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany;
5. Department of Neurosurgery, University at Buffalo, Buffalo, New York, USA