Nima Derakhshan1,2, Mahsa Roshanfarzad3. 1. Student research committee, Neurosurgery Department, Shiraz University of Medical Sciences, 71937-11351, Namazi Square, Zand Street, Shiraz, Iran. Nima_med83@yahoo.com. 2. Neurosurgery Office, Namazi Hospital, Shiraz University of Medical Sciences, Namazi Square, Zand Street, Shiraz, 71973-11351, Iran. Nima_med83@yahoo.com. 3. Student research committee, Neurosurgery Department, Shiraz University of Medical Sciences, 71937-11351, Namazi Square, Zand Street, Shiraz, Iran.