1. Surgery Department, College of Medicine, Al Majmaah University, P.O. Box 47212, Riyadh 11552, Saudi Arabia
2. Division of Neurosurgery, Department of Surgery, King Abdulaziz Medical City, P.O. Box 22490, Riyadh 11426, Saudi Arabia
3. Division of General Surgery, Department of Surgery, King Abdulaziz Medical City, P.O Box 22490, Riyadh 11426, Saudi Arabia