1. Department of Neurosurgery, University of Baghdad, Baghdad, Iraq
2. Department of Neurosurgery, University of Al-Mustansiriyah, Baghdad, Iraq
3. Department of Neurosurgery, Neurosurgery Teaching Hospital, Baghdad, Iraq
4. Department of Neurosurgery, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
5. Department of Neurosurgery, University of Pittsburgh, Pittsburgh, United States