1. Intern, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
2. Department of Neurosurgery, King Abdulaziz Medical City, Riyadh, Saudi Arabia.
3. Department of Pathology, King Saud University, Riyadh, Saudi Arabia.
4. Department of Neurosurgery, King Saud University Medical City, Riyadh, Saudi Arabia.