1. Departments of Neurosurgery, Espoo, Finland
2. University Hospital of Trondheim, Trondheim, Norway; and Orion Pharma, Espoo, Finland
3. Pathology, Espoo, Finland
4. Turku University Central Hospital, Turku, Finland; Department of Neurosurgery, Espoo, Finland
5. Tampere University Hospital, Tampere, Finland; Department of Neurosurgery, Espoo, Finland
6. Helsinki University Central Hospital, Helsinki, Finland; Department of Neurosurgery, Espoo, Finland