1. Departments of Neuroscience, The King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabi
2. Departments of Pathology, The King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabi
3. Departments of Radiology, The King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabi
4. Division of Neurosurgery, Georgetown University Hospital, 3800 Reservoir Road, Northwest, Washington, District of Columbia 20007.